General Seminar takes place every Monday at 11.15 in Piwnice, radioastronomy seminar room.
Remote participation via the virtual seminar room.
25 October 2021
“Implications of AGN feedback on high redshift galaxies”
dr Flora Stanley (Institut d’Astrophysique de Paris)
One of the main open questions of galaxy evolution is how active galactic nuclei (AGN) can affect the ongoing star-formation and interstellar medium (ISM) properties of galaxies. To reproduce the properties of galaxies in the local universe, cosmological and semi-analytical models of galaxy formation and evolution find it necessary to use AGN feedback as a regulator of star formation, in the form of heating and outflows of the surrounding gas. To find observational evidence that AGNs do have a significant role in regulating galaxy growth, we need to study the star formation and ISM properties of active galaxies. In this seminar, I will present the main results from my research on the SFR and ISM properties of AGN across cosmic time.
18 October 2021
“The retrograde world: Where did retrograde asteroids come from?”
dr Paweł Kankiewicz (Jan Kochanowski University of Kielce)
The asteroids with orbital inclinations greater than 90 degrees are generally known as retrograde asteroids. The first object of this kind was discovered in 1999, and after discoveries in 2007 and 2009, such two objects were classified as near-Earth objects (NEOs). There are various hypotheses related to the physical characteristics and formation of these types of objects. The physical and orbital similarity to comets suggests an origin from their hypothetical reservoir: The Oort Cloud. More recent hypotheses, in turn, do not exclude an interplanetary origin. The presented research and its results are the results of a project that comprehensively investigated the dynamics of bodies in retrograde orbits and verified scenarios of their orbital evolution. Methods were worked out to study their long-term evolution and to determine how long they live and remain in stable orbits in our planetary system. In statistical terms, it was also verified how plausible the scenario of inversion of such orbits is due to perturbations. A possible influence of non-gravitational effects on the results was also investigated.
11 October 2021
“Astrophysics with LIGO/Virgo Gravitational-wave Detections”
Prof. dr hab. Krzysztof Belczyński (Nicolaus Copernicus Astronomical Center, Polish Academy Of Sciences, Warsaw)
LIGO/Virgo Collaboration has published 50 detections from the first three observational campaigns (O1/O2/O3). The most interesting detections are putting a new perspective on black hole and neutron star formation. I will discuss the landscape of 1/O2/O3 detections and their implications for stellar evolutionary modeling. Broadly speaking, the basic observational properties of detected double black hole mergers are consistent with predictions of the classical isolated binary evolution of massive stars. However, these detections severely constrain stellar physics that is unaccessible by electromagnetic observations.
On the other hand, the first results from the O3 campaign seem to challenge classical binary evolution with black holes found in the lower and upper mass gaps. These are regions in which black holes are not expected to form from stars but rather form via dynamic interactions of stars in dense clusters. I will discuss these curious events in the context of their most likely formation sites.
4 October 2021
“Classification of Gaia microlensing events and hunt for black holes”
Dr Paweł Zieliński (Astronomical Observatory, University of Warsaw)
Gaia mission scans the entire sky in order to deliver the proper motions and distances for a billion stars. It is capable of detecting the photometric variability of stars like, e.g., microlensing events which are of particular interest in the context of searching for compact objects in our Galaxy. Gaia photometric and astrometric time-series can reveal lensing black holes of stellar masses. But due to Gaia cadence, it is crucial to conduct additionally photometric monitoring of as many microlensing events as possible from the ground. Therefore, a network of small and medium-sized telescopes was developed under the OPTICON grant financed by the EU Horizon2020. Data delivered by the network is being automatically processed and calibrated to science-ready data by using our new tool – Black Hole TOM (https://bh-tom.astrolabs.pl/). Moreover, also the spectroscopic follow-up observations by using world-class telescopes for selected Gaia transients were performed in order to early distinguish genuine microlensing events from other types of outbursts and variables reported by the Gaia Science Alerts system. The spectra helped us classify and select a sample of microlensing events for which an intensive photometric follow-up can be conducted. Thanks to them, we are also able to determine physical parameters of the source star, extinction and distance that is essential in constraining the microlensing model.
During my talk, I am going to present the status of our searches for black holes with recent examples of interesting events, the results of spectroscopic classification of candidates for microlensing events, as well as the capabilities and applications of BHTOM. Such small-scale operations provide good training ahead of the forthcoming influx of Galactic Plane transients from the LSST/VRO.
7 June 2021
“PL-612 LOFAR Baldy station. Current activities and further development”
Dr hab. Leszek Błaszkiewicz (Space Radio-Diagnostics Research Centre, University of Warmia and Mazury in Olsztyn)
The LOFAR radio telescope is an interferometric network initiated in the Netherlands, consisting of stations that are digitally controlled phase telescopes. Currently, 38 stations located in the Netherlands and 14 in other European countries participate in the network, including three in Poland. frequency range (30 – 80 MHz and 110 – 240 MHz) makes the telescope extremely useful in many types of astronomical research. During the lecture, technical aspects of the LOFAR instrument operation will be presented, with an emphasis on the operation of a single station, as well as the observational results obtained both during the observations of the entire system and its separate parts (core, single stations, ILT mode). The upcoming plans for enlargement of the system to the state known as LOFAR 2.0 will also be presented.
31 May 2021
“Changing paradigms in planet formation”
Dr Joanna Drążkowska (LMU Munich, University Observatory)
Our understanding of planet formation is being transformed thanks to the exoplanet detections and observations of circumstellar disks but also the increasing precision of measurements of the Solar System meteorites. This talk will present the emerging planet formation theory as a multifaceted process that starts with dust growth to pebbles. I will introduce our recent results suggesting that the Solar System architecture as we know it today is intimately connected to the earliest phases of the solar disk evolution.
24 May 2021
“Tidal evolution of galaxies in clusters”
Prof. Ewa Luiza Łokas (Nicolaus Copernicus Astronomical Center, Polish Academy Of Sciences, Warsaw)
Galaxies are subject to strong tidal evolution in the environment of clusters. I will discuss this process using the example of the most massive cluster of the IllustrisTNG-100 simulation that traces the formation and evolution of galaxies in the cosmological context. For the purpose of this work, I selected 112 galaxies in the cluster, with the largest stellar masses at present, and followed their properties over time. Using their orbital history, the sample is divided into unevolved (infalling), weakly evolved (with one pericenter passage), and strongly evolved (with multiple pericenters). The samples are clearly separated by the value of the integrated tidal force from the cluster the galaxies experienced during their entire evolution and their properties depend strongly on this quantity. As a result of tidal stripping, the galaxies lose mass and become significantly less dark matter dominated. The cluster environment is also very efficient in stripping the galaxies of their gas and quenching the star formation. The strongly evolved galaxies lose their gas earlier and faster, and they become redder and more metal rich, so that at redshift z=0.5 the population of galaxies in the cluster becomes predominantly red. As a result of tidal stirring, the morphology of the galaxies evolves from oblate to prolate and their rotation is diminished, thus the morphology-density relation is reproduced in the simulated cluster. The strongly evolved sample contains at least six convincing examples of tidally induced bars and six more galaxies that had their bars enhanced by their interaction with the cluster.
17 May 2021
“Monitoring of satellites and space debris and investigating their impact on astronomical observations”
Dr Krzysztof Kamiński (Institute Astronomical Observatory, Adam Mickiewicz University, Poznań)
The growing number of Earth orbiting artificial satellites and space debris raises important questions about human presence in space. Astronomical Observatory of Adam Mickiewicz University is joining the efforts in creating a European network of optical, laser and radar sensors to monitor the orbital evolution of space resident objects and help predict their collisions, atmospheric re-entries etc. This is a part of a wide array of activities orchestrated by the European Space Agency and the European Space Surveillance and Tracking Consortium in order to guarantee long term sustainability of utilization of Earth satellites. Additionally we are monitoring the situation from the point of view of astronomical observations which are threatened to some degree by large satellite constellations. In order to help mitigate the interference between astronomical research and space infrastructure development we are working on an on-line tool for predicting potential satellite signatures in recorded images.
10 May 2021
“Investigating the most promising Yarkovsky candidates using Gaia DR2 astrometry”
MSc Karolina Dziadura (Institute Astronomical Observatory, Adam Mickiewicz University, Poznań)
The orbital motion of small bodies is affected by the Yarkovsky effect. First-time the effect was proposed by Yarkovsky in 1901 and then popularized by Öpik in the 1950s. However, the first direct detection was only made in 2003 thanks to radar observations. Nowadays there are over hundred detections for NEAs and only a few for Main-Belt objects. The main goal of this study is to improve an asteroid orbit using GAIA DR2 astrometry. It was claimed that the Gaia mission will improve asteroids orbits and to find new Yarkovsky detections thanks to the high precision and accuracy of its astrometry. I converted all of the available data to ADES format and then used it to orbit determination. I used OrbFit software which is a Fortran program for orbit propagation, ephemerides computation, orbit determination, close approach analysis, and impact monitoring. I will show results for 42 asteroids, where for 21 of them I obtained an A2 parameter with signal to noise ratio greater than 3.
26 April 2021
“LOFAR Surveys: a new window on the Universe”
Prof. Huub Rottgering (Leiden Observatory)
The Low-Frequency Array (LOFAR) is a pan-European radio telescope whose massive data taking and processing capabilities make it an unprecedented powerful instrument for carrying out the deepest and widest radio surveys at low radio frequencies. Over the last years we have addressed important issues related to the analysis and calibration of the radio data so that we can now make thermal noise limited maps at low frequencies. The resulting wide and deep maps enable studies of a wide range of scientific topics ranging from (i) shocks in merging clusters, (ii) radio feedback processes, (iii) star formation in distant galaxies and (iv) the most distant radio galaxies, close to the epoch of reionisation.
In this talk I will first discuss our solutions to the main technical challenges. Secondly, scientific highlights will be given related to these 4 topics.
The seminar is organised as part of the academic partnership between NCU in Torun and Leiden University within the framework of the InterAPS project.
19 April 2021
“Random flows and rotation in galactic coronae”
Prof. Anvar Shukurov (School of Mathematics, Statistics and Physics, Newcastle University)
Galactic coronae are extended gas envelopes around the discs of spiral galaxies filled with a hot, rarefied gas produced by supernovae in the disc. They contain cosmic rays and magnetic fields and provide a reservoir for the magnetic helicity transported from the disc by the fountain flow. The nature and parameters of the turbulence and rotation in the coronae are poorly known and the existing rotation models struggle to explain the limited observations available. We discuss the sources of random motions in the coronae and argue that the gas is so viscous that developed turbulence cannot be maintained. We suggest that the observations are compatible with the diffusive spread of vorticity from the disc.
12 April 2021
“Gamma-ray emission from collisions of stars with jets in active galaxies”
Prof. dr hab. Włodzimierz Bednarek (University of Lodz)
Vicinity of super-massive black holes (SMBHs) in many galaxies are well established sites of high energy processes in which high energy gamma-rays are produced. This radiation is commonly believed to originate in relativistic collimated outflows which are powered by the accretion process onto SMBHs. On the other hand, SMBHs are surrounded by huge quasi-spherical systems of young stars on parsec distance scale, stars from the bulge on sub-kpc distance scale and also many globular clusters on kpc distance scale. Those stars (and stellar systems) can enter the jet region from time to time disturbing the jet flow and creating soft radiation field for energetic particles. The aim of the talk is to review a few scenarios in terms of which basic proprieties of gamma-ray emission can be understood. In particular, we discuss the gamma-ray production in the interaction of relativistic electrons: (I) accelerated on the shock around massive star and (II) the shock around globular cluster; (III) electrons accelerated within the relativistic blob in the jet; and (IV) gamma-rays, produced in the inner jet but, interacting with the radiation of a star crossing close to the direction towards the distant observer. Possible applications of those models to the recent gamma-ray observations by the satellite and Cerenkov telescopes will be also discussed.
29 March 2021
“Doing peripheral science? Johannes Hevelius, Maria Cunitia and Elias von Löwen and the development of astronomy in the 1st half of the 17th century”
Prof. dr hab. Jarosław Włodarczyk (Institute for the History of Science, Polish Academy of Sciences, Warsaw)
The correspondence of Johannes Hevelius (1611–1687) comprises a set of 22 letters written in the years 1648–1654 and exchanged with Maria Cunitia (1610–1664) and her husband, Elias von Löwen (Crätschmair, c. 1602–1661), a couple based in Silesia. Maria Cunitia is acknowledged for her Urania Propitia (1650), an innovative adaptation of the mathematical astronomy of Johannes Kepler’s Rudolphine Tables (1627). In turn von Löwen authored astronomical calendars and ephemerids.The letters can be seen as an extraordinary example of the exchange of thoughts involving, on the one hand, a representatives of the mainstream European astronomy of the 17th century (Hevelius) based in an acknowledged scientific center (Gdańsk) and, on the other, astronomers working in the periphery of then scientific Europe. The correspondence features several significant astronomical themes, which cast new light on the activities of astronomers in the first half of the 17th century, and even on the chronology of discoveries. These include telescopic observations of the positions of the planets made to verify the accuracy of astronomical tables, studies of the optical libration of the Moon in the period preceding Galileo Galilei and Hevelius, discussion of the usefulness of various observational tools such as the telescope, the ways of purchasing telescopes in the first half of the 17th century and their dissemination outside major scientific centers. The correspondence proves unique because it describes the activities of astronomers who work independently and far away from the major academic centers. Furthermore, the fact that it is a woman who seems to be the major vehicle of the 17th century scientific inquiries, makes the letters a particularly interesting source for researches of social history and history of science, including those with feminist agenda.
22 March 2021
“Eppur si muove. On the Origin of Long Secondary Periods in Red Giant Stars”
Prof. dr hab. Igor Soszyński (Astronomical Observatory, University of Warsaw)
Long secondary periods (LSPs), observed in a third of pulsating red giant and supergiant stars, are the only unexplained type of large-amplitude stellar variability known at this time. Numerous authors have explored various scenarios for the origin of LSPs, but were unable to give a final solution to this problem. I will present known properties of LSP variables and show new results proving that the physical mechanism responsible for LSPs is binarity. Namely, the LSP light changes are due to the presence of a dusty cloud orbiting the red giant together with the brown-dwarf companion and obscuring the star once per orbit. In this scenario, the low-mass companion is a former Jupiter-like planet that accreted a significant amount of mass from the envelope of its host star and grown into a brown dwarf.
15 March 2021
“Sky surveys at CAPS: DES, DELVE, and LSST”
Dr Monika Adamów (National Center for Supercomputing Applications (NCSA) University of Illinois at Urbana-Champaign)
The Center for Astrophysical Surveys (CAPS) at the University of Illinois at Urbana-Champaign is involved in several sky surveys. In my presentation, I would like to advertise three of them: Dark Energy Survey and DELVE, both with very recent public data releases, and Legacy Survey of Space and Time (LSST) – a project conducted by Vera C. Rubin Observatory. This project is currently in the construction/commissioning phase, with the regular science operations planned for the beginning of 2023.
8 March 2021
“Constraints on the efficiency of convective transport from asteroseismology of AF-type stars”
Prof. dr hab. Jadwiga Daszyńska-Daszkiewicz (Astronomical Institute, University of Wrocław)
Depending on physical conditions inside a star, the energy produced in the centre can be transported to the surface by radiation, convection or conduction. The treatment of stellar convection in the outer layers is one of the most fundamental problems in stellar physics. The motion of a convective element is extremely difficult to describe and, usually, it is done in stellar evolution calculations in the framework of the so-called mixing-length theory (MLT). The convective efficiency within MLT is measured by the parameter $\alpha_MLT$, the value of which cannot be derived from the first principles.
In this talk, I will present what information about convection in stellar envelopes can be obtained from asteroseismic studies of the main sequence pulsators of AF spectral type. I will discuss the results for the two stars: SX Phoenicis and $\delta$ Scuti. These stars are the prototypes of a class of pulsating stars of Population II and Population I, respectively.
1 March 2021
“Planetary migration, periodic orbits and mean motion resonances”
Dr hab. Cezary Migaszewski (Institute of Astronomy, Nicolaus Copernicus University)
This talk is devoted to the relationship between planetary migration and mean motion resonances. The stabilising role of the latter is discussed in the context of data analysis and characterisation of multi-planet systems, especially those that are poorly constrained by observations. Particular emphasis is placed on periodic orbits as centres of resonance. Knowledge of such configurations can be used to properly interpret observations, which in turn can help to better relate observational characterisation results of known planetary systems to their migration-induced formation models.
22 February 2021
“Statistical analysis of blazar variability”
Dr Arti Goyal (Astronomical Observatory, Jagiellonian University, Kraków)
The power-law form of blazar variability power spectral densities (PSDs) with slopes ranging from 1–3 indicate that the variability is generated by underlying colored noise type stochastic processes. Here, we present the results of our PSD analysis using both Fourier domain and time domain approaches on multiwavelength datasets (GHz band radio–very high energy gamma–ray energies) and covering timescales ranging from a few decades to minutes. Our main results are the following: (1) nature of the variability process at synchrotron frequencies is different from those at Inverse Compton frequencies (slopes 2 and 1) of the emission spectrum; this could imply, that gamma-ray variability, unlike the synchrotron (radio-to-optical) one, is generated by the superposition of two stochastic processes with different relaxation timescales, (2) the main driver behind the optical variability is same on decades, years, months, days, and hours timescales (slope=2), which argues against the scenario where different drivers behind the long-term and intra-night flux changes are considered. Our results do not easily fit into a simple model, in which a single compact emission zone dominates the radiative output of blazar across all the timescales probed. Instead, we argue that the frequency-dependent shape of the variability power spectra points out a more complex picture, with highly inhomogeneous outflow producing non-thermal emission over an extended, stratified volume.
18 January 2021
“Variability in SMEI data”
MSc Przemysław Mikołajczyk (Astronomical Institute, University of Wrocław)
The Solar Mass-Ejection Imager (SMEI) was an experiment designed to detect and measure transient plasma features in the heliosphere, including colornal mass ejections. As it was observing the whole sky with its three cameras with total field-of-view of 180 deg x 3 deg, images of the whole sky have been taken roughly every one orbit (~100 minutes) for over 8 years. In order to remove bright objects (stars, planets, clusters, SolarSystem minor bodies etc.) PSF photometry has been performed. Time-series photometry for ~5600 objects is a side effect of SMEI performing its main objective. In my presentation, I will show what the SMEI data looks like and highlight existing differences between the two data releases. I will discuss the data quality and show methods to improve quality of PSF photometry. Finally, I will show some examples of SMEI data analysis regarding known variable sources as well as the results of a variability survey among O and B stars, which constitute a major part of my PhD thesis.
11 January 2021
“Spectroscopy of the helium-rich binary ES Ceti reveals accretion via a disc and evidence for eclipses”
Dr Karolina Bąkowska (Institute of Astronomy, Nicolaus Copernicus University)
Amongst the hydrogen-deficient accreting binaries known as the “AM CVn stars” are three systems with the shortest known orbital periods: HM Cnc (321 sec), V407 Vul (569 sec) and ES Cet (620 sec). These compact binaries are predicted to be strong sources of persistent gravitational wave radiation. HM Cnc and V407 Vul are undergoing direct impact accretion in which matter transferred from their donor hits the accreting white dwarfs directly. ES Cet is the longest period of the three and is amongst the most luminous AM CVn stars, but it is not known whether it accretes via a disk or direct impact. ES Cet displays strong HeII 4686 line emission, which is sometimes a sign of magnetically-controlled accretion. Peculiarly, although around one-third of hydrogen accreting white dwarfs show evidence for magnetism, none have been found amongst helium accretors.
We present the results of Magellan and VLT spectroscopic and spectropolarimetric observing campaigns dedicated to ES Cet with the aim of understanding its accretion structure.
We find strong variability in our spectra in the 620 sec period. The lines show evidence for double-peaked emission, characteristic for an accretion disc, with an additional component associated with the outermost disc, rather than a direct impact, that is broadly consistent with “S”-wave emission from the gas stream/disc impact region. This confirms beyond any doubt that 620 sec is the orbital period of ES Cet. We find no significant circular polarisation (below 0.1 %). The trailed spectra show that ES Cet’s outer disc is eclipsed by the mass donor, revealing at the same time that the photometric minimum coincides with the hitherto unrecognised eclipse.
ES Cet shows spectroscopic behaviour consistent with accretion via a disc and is the shortest orbital period eclipsing AM CVn star known.
4 January 2021
“Observations of maser emission performed with RT4”
MSc Michał Durjasz (Institute of Astronomy, Nicolaus Copernicus University)
Toruń 32-m radio telescope RT4 participates in numerous VLBI sessions every year – but what it does when the sessions are over? It mostly observes maser emission that origins in vicinity of massive protostars. Surveys of the OH masers at 6 GHz and methanol masers at 12 GHz resulted in finding new sources – detection of multiple lines that originate in the same place allows us to constrain physical properties around young massive stars. Also, Zeeman pairs of the OH masers are useful in research of magnetic fields. We also managed to detect 6.7 GHz methanol maser flares due to regular monitoring.
21 December 2020
“Dissecting star-forming regions toward IRAS 22147+5948”
Dr Maciej Koprowski (Institute of Astronomy, Nicolaus Copernicus University)
Outer Galaxy consists of star-forming regions spanning various galactocentric distances and thus allows us to trace the impact of the environment on star formation. The star-forming region associated with IRAS 22147+5948 suffers from cloud confusion and unclear status based on radio continuum observations, suggesting a presence of supernova remnant or HII region. In this talk, I will explain how the machine-learning techniques, spectral energy distribution modelling, clustering, and gas and dust maps were used to disentangle and characterize distinct populations of YSOs associated with IRAS 22147+5948. I will also describe all the analysis that was performed in order to confirm the status of IRAS 22147+5948 region as a star formation site.
14 December 2020
“Chemical Complexity in the Protostellar Environment”
Dr Hannah Calcutt (Chalmers University of Technology, Sweden | Institute of Astronomy, Nicolaus Copernicus University)
Complex organic molecules are found everywhere in the interstellar medium, especially in the warm and dense gas close to forming stars, from which planets eventually emerge. Understanding the origin of these molecules and their chemistry is important to determine the complexity of chemistry that can develop, and its potential implications to life in the universe. These molecules can also be used as tools to understand the mechanisms central to the formation of stars. ALMA has revolutionised the observation of these molecules, providing the tools to perform unbiased surveys of the molecular content on solar system scales. This talk will explore the many challenges of large chemical surveys in star-forming regions. I will present the key results from my work expanding our understanding of the physical structure and evolution of star-forming regions and discuss how far we have come in building up a unified picture of chemical variability in the protostellar environment and how far we have to go.
7 December 2020
“Diffuse Emission from the Inner Galaxy as measured with the HAWC Observatory”
MSc Amid Nayerhoda (Institute of Nuclear Physics, Polish Academy of Sciences, Kraków)
The Galactic gamma-ray diffuse emission is produced by the interaction of cosmic rays with ambient gas and electromagnetic radiation fields in the interstellar medium (ISM). Studying this radiation helps reconstructing the particle transport mechanisms and the particle distribution in the Galaxy. The analysis of HAWC TeV emission from a region of the Galactic plane is presented here. The energy and spatial distributions of the diffuse Galactic gamma-ray emission have been studied after subtracting extended and point sources detected with greater than 5 sigma significance from the region map. The spectral and morphological features of the measured emission are compatible with the gamma-ray emissivity obtained from the locally measured proton spectrum, convolved with the gas distribution in the Galaxy.
30 November 2020
“Metal-poor massive stars: The theory linking gravitational waves, star-formation and the dawn of the Universe”
Dr Dorottya Szécsi (Institute of Astronomy, Nicolaus Copernicus University, University of Cologne)
What do gravitational waves have in common with ancient globular clusters? What links these to cosmic explosions like gamma-ray bursts, to the energetic radiation in star-forming galaxies and even to the dawn of our Universe? What they have in common, is that all these phenomena — and more — have been theorized to stem from metal-poor massive stars, in one way or another. In my talk, I will explain these theories, and suggest new perspectives on how to combine them.
23 November 2020
“Periodic maser flares in high-mass star-forming regions”
MSc Mateusz Olech (Institute of Astronomy, Nicolaus Copernicus University)
The 6.7 GHz methanol maser emission is identified as an important tracer of early stages of high-mass star formation. Thanks to its characteristics we can study properties and dynamics of matter as close as 1000au from the protostar, region not easily reachable by other methods of observations. In recent years, long-term monitoring of methanol masers led to the discovery of small subgroup of 26 objects displaying periodic flares with periods ranging from less than a month to almost 2 years. To this day the mechanism driving those flares is not known and many competing theories were proposed. In my talk, I will summarize near 10 years of research conducted by Toruń maser group in this field and present our latest findings.
16 November 2020
“The Nobel Prize in Physics 2020”
Prof. Jean-Pierre Lasota (CNRS Institut d’Astrophysique de Paris; Sorbonne Université, Nicolaus Copernicus Astronomical Center, Warsaw)
I will present and discuss the discoveries and services to physics that have been rewarded by this year Nobel Prize in Physics. In particular, I will try to explain why Roger Penrose has been rewarded for his work on black holes while Reinhard Genzel and Andrea Ghez got the prize for the discovery not of a black hole but of a “supermassive compact object” at the centre of our galaxy.
9 November 2020
“The orbital architecture and stability of the HR 8799 planetary system”
Prof. dr hab. Krzysztof Goździewski (Institute of Astronomy, Nicolaus Copernicus University)
A system of four planets of ~10 Jupiter mass around HR 8799 is the first multi-planet configuration discovered via the direct imaging (Marois+, Science 322, 2008; Nature 468, 2010). The system’s architecture is still unresolved, due to narrow observing window of ∼20 yr that covers tiny arcs of orbits with periods from roughly 50 to 500 yr. Unconstrained best-fitting astrometric configurations self-disrupt rapidly due to mutual gravitational interactions. For a decade, we argue that the HR 8799 system may be long-term stable when locked in a particular mean-motion resonance (MMR), similar to the 4:2:1 Laplace resonance of the Galilean moons. We present new results of modeling this intriguing planetary system, taking into account the broader perspective of planetary systems detected via the direct imaging.
26 October 2020
“The origin of the [WC] central stars of planetary nebulae”
Dr Marcin Hajduk (University of Warmia and Mazury, Olsztyn)
[WC] stars are central stars of planetary nebulae (PNe) which show spectra dominated by broad emission lines of carbon and helium. The lines originate from intense and fast winds blowing from their surface, similar to massive Wolf-Rayet (WR) stars of carbon sequence. Different theoretical models predict different evolution speed and chemical composition of [WC] stars. I have determined the temperature evolution of a sample of [WC] stars, which indicates that [WC] stars originate from more massive progenitors than hydrogen-rich central stars.
19 October 2020
“Planetary tides in the WASP-12 and WASP-18 systems”
Dr hab. Gracjan Maciejewski, prof. NCU (Institute of Astronomy, Nicolaus Copernicus University)
Massive exoplanets on extremely tight orbits, so called hot Jupiters, induce equilibrium tides in their host stars. The tidal fluid flow in the stars can be detected with the radial velocity (RV) method. Using precise RV measurements acquired with the HARPS-N spectrograph at the Telescopio Nazionale Galileo and the HIRES instrument at the Keck-I telescope we show that the subtle RV signal of the photosphere following the planetary tidal potential can be distilled for the host stars in the WASP-12 and WASP-18 planetary systems. For WASP-18, the amplitude of those tides was found to agree with both theoretical predictions of the equilibrium tide approximation and an ellipsoidal modulation observed in an orbital phase curve. For WASP-12, the tides turned out to be 50% larger than expected. Those findings open new possibilities in probing the physical properties of stellar interiors.
12 October 2020
“The latest TDE science news”
Dr Mariusz Gromadzki (Astronomical Observatory, University of Warsaw)
In Astronomy, the term Tidal Disruption Event (TDE) is reserved for transients caused by disruption of a star by a Supermassive Black Hole (SMBH). Those phenomena proposed in the mid 70’s show a variety of physical processes including streams interaction, accretion disk formation and high-velocity outflows. They give evidence of SMBH presence in centres of quiet galaxies, allowing for estimates of BH masses and in some cases also their spin. After almost thirty years first candidates were discovered. Currently, nearly forty has been observed. In this seminar talk, I will present progress which happened in recent years in this field, emphasising the role of ESO ePESSTO programmes.
5 October 2020
“How to find a nearby black hole?”
Dr hab. Łukasz Wyrzykowski (Astronomical Observatory, University of Warsaw)
Black holes (BH) are everywhere, there should be hundreds of millions of stellar-origin black holes in our Milky Way Galaxy. However, we only know about 50 or so cases, mostly from X-ray binaries, where a BH accretes matter from its stellar companion, or from binary system involving a star and a BH. Single black holes, even if nearby, are essentially black and invisible.
Gravitational microlensing offers an opportunity to discover black hole and other dark objects just by the fact they are massive and bend the background light. There have been thousands of microlensing events discovered by OGLE, Gaia, ZTF and other projects. However, in order to uniquely recognise a black hole lens and distinguish from a regular stellar lens, it is required to measure the size of the Einstein Radius as well as the distances of both lens and the source. Gaia space mission’s astrometric data will allow measuring Einstein radii for all events, however, without a dense photometric coverage of their light curves, the parallax effect will not be measurable.
The Time-Domain work package of the EC’s Horizon 2020 OPTICON grant has been established in order to coordinate global long-term time-domain observations, such as of candidates for lensing black holes. In years 2021-2024, these actions will be extended also to radio time-domain observations, within the new Horizon 2020 grant OPTICON-RadioNET PILOT (ORP), where UMK will be also a partner. In my talk, I will describe the current state of the black hole microlensing searches and will present the results obtained so far with the OPTICON Time-domain telescope network. I will also present the possibilities of extending the microlensing black hole search to radio sources.
22 June 2020
“Looking at Galactic metal-poor stars with Gaia and large spectroscopic surveys”
Prof. Rodolfo Smiljanic (Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Warszawa)
Recently, thanks to Gaia kinematic data, it has become evident that the inner part of the Galactic halo is strongly dominated by accreted stars. The accreted system originally had a mass similar to the one of the Small Magellanic Cloud and merged with the Milky Way about 8-10 Gyr ago. The study of chemical abundances in accreted and in situ stars can reveal the star forming conditions in the different sub-systems that formed the halo and the thick disk. I this context, I will report on preliminary results of a chemo-kinematic analysis of metal-poor stars observed by the Gaia-ESO Survey. The analysis uses machine learning techniques to disentangle the various stellar populations at the low-metallicity regime, including the thick disk, the metal-weak thick disk, and the different halo components. I will also briefly mention our related efforts to separate accreted and in situ stars using data from other large spectroscopic surveys.
8 June 2020
“HIRES, the high resolution spectrograph for the ELT: the phase A study and the path to construction”
Prof. Alessandro Marconi (Department of Physics & Astronomy University of Florence, Italy, Associated to INAF-Arcetri Astrophysical Observatory)
I will present the current status and the path to construction of HIRES, an optical-infrared High Resolution Spectrograph for the ELT. A successful Phase A study has been completed in 2018 by a consortium of more than 30 institutes, including the university of Torun from Poland. The consortium is now preparing for Phase B and to bring the instrument to the telescope. I will present an overview of the project, describing the science case and the baseline design. The top science cases of ELT-HIRES will be the detection of life signatures from exoplanet atmospheres, tests on the stability of Nature’s fundamental couplings, the direct detection of the cosmic acceleration. However, the science requirements of these science cases enable many other groundbreaking science cases. The baseline design, which allows to fulfil the top science cases, consists of a modular fiber-fed cross-dispersed echelle spectrograph providing a simultaneous range of 0.4-1.8 µm at a resolution of 100,000 and with several observing modes. I will then conclude by presenting current activities and the path to construction.
3 June 2020
Special Institute of Astronomy Seminar
“Particle acceleration mechanisms”
Dr Grzegorz Kowal (Escola de Artes, Ciências e Humanidades, Universidade de São Paulo.)
The first observations of high-energy radiation, commonly known as cosmic rays, took place over one hundred years ago. Soon after the discovery of cosmic rays, Victor Hess in 1912 confirmed with his observations, that they are mostly of galactic or extragalactic origin. Their origin and nature still puzzles the modern astrophysics and is considered one of the problems which is not yet resolve. In the first part of my talk I will briefly describe what we know about the properties of cosmic rays from observations. The following part will be dedicated to the discussion on the physical mechanisms, such as diffusive shock acceleration and turbulence, believed to be responsible for accelerating thermal particles to high energies. Finally, in the last part I will present the results of our studies on first-order Fermi acceleration by fast turbulent reconnection.
1 June 2020
“Nowa Hewelusza (1670) – efekt koalescencji małomasywnego czerwonego olbrzyma z ?”
Prof. Romuald Tylenda (Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Toruń)
Przedstawie wyniki obserwacyjnego wyznaczenia skladu chemicznego i izotopowego materii w CK Vul (pozostalosc po wybuchu Nowej Cygni obserwowanej przez Jana Heweliusza w latach 1670-72). Na ich podstawie pokaze, ze przed wybuchem byl to malomasywny (0.9-1.3 Mo) czerwony olbrzym, ktory zapewne ulegl koalscencji z innym obiektem gwiazdowym w 1670 r.
25 May 2020
Dr Asta Heinesen (CRAL-ENS, UCB Lyon)
I will give an introduction to the field of inhomogeneous cosmology focusing on averaging schemes for formulating a large scale cosmological theory from a general relativistic space-time. An important insight from the averaging formalism discussed is that structure in a relativistic space-time induces violation of the spatial curvature conservation law of the Friedmann-Lemaitre-Robertson-Walker class of models usually used for interpreting cosmological data. Such a violation, if significant, would have important physical and observational consequences. I will mention some questions of interest in inhomogeneous cosmology and talk about some of my own work in relation to these questions.
11 May 2020
“Absorption spectra of interstellar clouds”
Prof. Jacek Krełowski
Translucent interstellar clouds produce three kinds of absorptions: continuous extinction, believed to be caused by interstellar dust particles, identified bands of simple radicals (OH, OH+, CH, CH+, NH, CN, C2 and C3) and more than 500 unidentified diffuse interstellar bands (DIBs). The latter are commonly believed to be carried by complex molecular species; however, none of them was until now identified beyond a doubt. The talk will compare the above mentioned absorptions in different interstellar clouds. It is to be emphasized that physical conditions inside individual clouds can be drastically different. It seems important that any change of the extinction law is accompanied by changes in molecular and diffuse spectra. This demonstrates complex chemistry of translucent interstellar clouds. The observed molecular species are likely building bricks for prebiotic molecules.
27 April 2020
“If the Universe were flat, galaxies could not have formed”
Prof. Boudewijn Roukema
Interpretations of extragalactic observations within the family of homogeneous isotropic solutions of the Einstein equation – the FLRW models – are usually described as showing that the Universe is very close to being flat. But is this really possible physically? The curvature that is usually associated with primordial density perturbations is often described as a gauge choice – an interpretation rather than an intrinsic physical, geometrical property. The turnaround epoch of an overdensity is the moment when instead of expanding more and more slowly than the surrounding Universe, the overdensity switches to a contracting phase. The relativistic Zel’dovich approximation method of modelling both cosmological expansion and structure formation shows that at this epoch, the curvature parameter is typically above five times the critical density parameter in amplitude, corresponding to a strongly positive curvature. If the spatial section of the Universe were really flat, galaxies could not have formed.
Reproducibility script: https://bitbucket.org/broukema/1902.09064
9 March 2020
“Kinematics of Coronal Mass Ejections and the associated Large Solar Energetic Particles during Solar Cycle 24”
MSc Anitha Ravishankar (Astronomical Observatory, Jagiellonian University, Kraków)
A detailed study of the properties of Solar Energetic Particles (SEPs) and their correlation with the associated Coronal Mass Ejections (CMEs) and Solar Flares is crucial for Space Weather forecast. It is well known that the CME speeds and SEP fluxes have good correlation. We have further examined this correlation by employing instantaneous speed (maximum speed, speed at SEP peak flux and Mach number at SEP peak flux) to check if they are a better indicator of SEP fluxes than the average speed. Our preliminary results show a better correlation by this approach (R=0.810 for >10 MeV energy band). We have extended this approach by studying the delay between the peak CME speed and peak SEP flux at multiple energy bands. We add the onset of type II radio burst to study the shock parameters associated with each event in our sample. In contrary, peak X-ray flux of solar flares and SEP peak flux show a poor correlation in our preliminary results (R=0.084 for >10 MeV energy band). We would like to investigate the contribution of flares to impulsive SEP events at close proximity to the Sun. In addition, we present our preliminary results on correlation between flare X-ray flux and electron and other ion fluxes. Furthermore, we would like to extend our sample to other solar cycles by using GCS model. The data of SOHO and STEREO are used for CMEs, GOES for particle fluxes and WIND/Waves for shock parameters. The scientific merit of our work is to provide a potential model for prediction of large geoeffective SEPs.
2 March 2020
“Overview of recent highlights from HESS”
Prof. dr hab. Bronisław Rudak (Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Toruń)
The High Energy Stereoscopic System is the ground-based TeV gamma-ray observatory, located in Namibia. Its results are of profound importance to the progress of high-energy astrophysics in the context of understanding a variety of galactic and extragalactic phenomena. The talk will present main achievements of HESS, including the first detection of a TeV gamma-ray afterglow of a bright gamma-ray burst. Prospects of multiwavelength observations with HESS as well as multi-messenger program will be discussed.
27 January 2020
“Theory vs. observations – Some of the properties of cataclysmic variable stars”
Dr Karolina Bąkowska (Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Warszawa)
Cataclysmic variable stars are close binary systems containing white dwarf (the primary) and main sequence star (the secondary). In those system the matter flows from the secondary to the primary component. Due to non-zero momentum, in some of the systems, the matter does not hit the white dwarf directly, but it creates accretion disc or accretion columns around the primary component. In the light curves of some of cataclysmic variables, we can observe outbursts and superoutburst. Superoutbursts are about 1 magnitude brighter and they last longer than typical outbursts. During superoutbursts there are periodic tooth-shaped oscillations called superhumps. Time between outbursts and superoutburst when the amout of light observed in the lightcurves is approximately the same is called quiescence. Y. Osaki in his model assumes constant mass transfer during outbursts and superoutbursts and an eccentric disk and tidial instability as an orgin of superhumps and superoutbursts but in papers published by J. Smak it is presented that the mass transfer from the secondary is strongly enhanced and the orgin of superhumps and superoutbursts are variable hot spot brightness and enhanced mass transfer, respectively. Because of such discrepancy between proposed models the new observations and analysis for cataclysmic binary stars were strongly required. I would like to present the outcome of the campaign dedicated to analysis of a few eclipsing cataclysmic variables during quiescence and outbursts/superoutbursts.
20 January 2020
“How infrared observations change our knowledge about galaxies?”
Dr Katarzyna Małek (National Centre for the Nuclear Research, Warszawa)
Infrared (IR) radiation is the key wavelength range for investigating the formation of stars, both in the Milky Way and in other galaxies. Dusty clouds around newly formed young stars are heated by their UV emission, and this energy is re-radiated in the IR. The resultant spectrum of the IR radiation is a result of a complex interplay of dust absorption and scattering effects, known under a common name of dust attenuation. Consequently, the dust attenuation shapes the spectral energy distributions (SEDs) of galaxies themselves, and any SED modelling and fitting procedure must account for this process.
In my talk, I will present how the unique Herschel Extragalactic Legacy Project (HELP) data were used to study the dust attenuation properties in galaxies. The primary objective of the HELP project is to provide an exceptional, homogeneously calibrated, multiwavelength galaxy catalogues covering roughly 1300 deg2 of the extragalactic Herschel Space Observatory surveys at wide redshift range. Millions of galaxies with UV–FIR photometry make HELP an exceptional project which can push the boundaries of our scientific understanding of multi-λ data. I will show the recently measured dust attenuation curves of star-forming galaxies, and the influence of different attenuation laws, on the estimates of galaxy properties, including galaxy stellar mass – the key physical parameter of every galaxy.
13 January 2020
“Low frequency observations of blazars”
Dr Urszula Pajdosz-Śmierciak (Astronomical Observatory, Jagiellonian University, Kraków)
I would like to present low energy radio observations of a diffused blazars’ emission. This work has been done on the basis of available archival data, as well as dedicated observations using LOFAR, GMRT and JVLA radio interferometers. I am going to focus mainly on blazar SBS B1646+499, which merges the properties of BL Lacs and Flat Spectrum Radio Quasars. This little-known source turned out to possess extended radio emission, confirmed by the latest interferometric maps and reaching almost 1 Mpc in length. This kind of 0 class AGN has been observed for the first time. What is more, it has been proved that low-energy, high resolution observations with good sensitivity and dynamics, could provide the information on the past phases of blazars’ activity, which – in this case – should be considered in terms of the unification scheme of Active Galaxies.
16 December 2019
“2019 Nobel Prize for 51 Peg b”
Prof. Andrzej Niedzielski
After three decades of exoplanet hunt we know of thousands of exoplanetary systems. Search for exoplanets and their characterisation became one of the main topics of astronomy these days, with a number of space missions already completed or ongoing, and new planned. But who found the first exoplanet ever? In my short introduction to exoplanets I will try to answer that question.
9 December 2019
“Nobel prize for physics 2019: co-winner Jim Peebles”
Prof. Boudewijn Roukema
Jim Peebles was the author and co-author of several key papers from the 1960s to the 1980s related to cosmological nucleosynthesis, the cosmic microwave background, the formation of large-scale structure in the Universe, the role of dark matter in solving several physical puzzles and the likely relevance of a cosmological constant required to fit cosmological observations within the context of the homogenenous isotropic family of cosmological solutions of the Einstein equation. An overview of these key contributions by Peebles to non-global aspects of physical cosmology, for which he was co-awarded the 2019 Nobel prize for physics, will be presented.
2 December 2019
“Zooming in on GW170817 at radio waves”
Dr Marcin Gawroński
The discovery of a gravitational wave/kilonova GW 170817 marked an important date in the history of modern astrophysics. GW 170817 afterglow was detected through the whole range of electromagnetic radiation, and an intense observing campaign then took place to study its physical properties. Our 32-m radio telescope was also involved in GW 170817 observations during two dedicated EVN experiments. Interpretation of the long-lived radio, optical, and x-ray emission suggested the launch of a jet from the remnant of the binary neutron star merger.
During my talk I will summarise results obtained so far in the radio domain, and present our recent findings based on the EVN data that were published in Science.
25 November 2019
“AGN’s life cycle – short-lived radio sources”
MSc Aleksandra Wołowska
The evolution of extragalactic sources has been an important issue in the study of active galactic nuclei (AGNs) for many years and is still a subject of deliberation. Standard evolutionary model created based on numerous observations assumes that GPS (Gigahertz Peak Spectrum) and CSS (Compact Steep Spectrum) sources are precursors to a large-scale radio-galaxies of FRI/FRII type.
During their evolution the radio jets of compact sources try to leave their host galaxy and develop into a large-scale structures, however, statistical studies have revealed that there is a significant excess of small, low-luminosity sources in comparison to powerful, fully developed, luminous radio-galaxies. This indicates that not all GPS and CSS are able to evolve into large-scale structures, and some of them show intermittent, recurrent activity on a scale of several thousands years. Those objects represent a new population of transient active galaxies that is yet to be fully discovered and studied.
During my speech I will present extensive observational data, and their interpretation, for several transient AGNs discovered with JVLA Caltech-NRAO Stripe 82 Survey.
18 November 2019
“Periodic variability of 6.7 GHz methanol maser sources”
MSc Mateusz Olech
Methanol maser emission at 6.7 GHz is widely recognized as a tracer of high-mass young stellar objects. Its characteristics give us the opportunity to study in unprecedented detail the physical properties and dynamics of protostellar environment. In last 15 years long-term monitoring of methanol maser sources unveiled the existence of a small group of 26 objects displaying periodic variability. The periods range from 24 days up to 2 years with widely different flare profiles and amplitudes. Many mechanisms were proposed to explain this behaviour but there still is no consensus between researchers. In my talk I will summarize the progress of near 10 years of research conducted by our group in this field and present our latest findings.
4 November 2019
“Stellar-merger remnants: what is left after two stars collide”
Dr Tomasz Kamiński (Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Toruń)
Red novae, a newly-recognized group of eruptive variable objects, are optical manifestations of merging non-compact stars that may be observed in real time. They represent transients erupting at luminosities intermediate between those of classical novae and supernovae. In red nova eruptions, stellar coalescence produces circumstellar environments very rich in molecular gas and dust. ALMA, NOEMA, and SMA have recently revealed the complexity of the cool remnants of such events, including their spatio-kinematic structure and a rich molecular inventory of peculiar molecular and isotopologic composition. The submillimeter observations have provided, for the first time, the masses dispersed during the merger events and revealed bipolar outflows, which strongly constrains hydrodynamic models of progenitor common-envelope systems and violent stellar mergers. Additionally, detailed studies of chemical composition of red-nova remnants have yielded many surprises and include the detection of complex organic molecules and the first observation in space of a “radioactive molecule”, 26AlF. I am going to give an overview of how merger remnants look like years, decades and centuries after the coalescence. This work constitutes a starting point of the MERGESTARS project soon to kick off in CAMK Toruń.
28 October 2019
“GAME and how to play it – FFTS observations and data reduction”
MSc Rafał Sarniak
The GAME (Great Astronomical Map Executor) program was created for the purpose of observation with the RT4 radio telescope at the Astronomical Observatory of the Astronomy Center of the Nicolaus Copernicus University in Toruń. Its main purpose is to use the FFT spectrograph with 100 MHz bandwidth for observation and to enable their reduction.
During my speech I will present new possibilities for spectral observations with the RT4 radio telescope and the FFTS broadband spectrograph. The GAME software and the observation modes it provides will be discussed.
21 October 2019
“Thermal properties of slowly rotating asteroids”
dr Anna Marciniak (Institute Astronomical Observatory, Adam Mickiewicz University, Poznań)
Asteroids are remnant building blocks left over from planetary formation. Studying them reveals clues about the origin and formation of ours but also other planetary systems.
Asteroids seen in the thermal infrared reveal their intrinsic properties like size, albedo, thermal inertia or surface roughness. Determining these parameters is only possible though, when at least spin period and spin axis orientation are known. To fully utilize the potential in variety of thermal data from infrared space missions like WISE, AKARI, IRAS or Herschel, a precise shape model of an asteroid is also needed.
Spin and shape models of asteroids are routinely created using convex inversion method from multi-apparition data in the visible light. However, due to various selection effects there is a lack of spin and shape models for slow rotators, especially when slow rotation is coupled with small amplitude of the lightcurve. These features make such targets perfect asteroid calibration sources for ground and space-based infrared observatories like ALMA, APEX or IRAM. Also, there are hints of increasing thermal inertia with the rotation period, but due to very small number of slow rotators with TPM applied, they still lack firm confirmation.
I am going to present our campaign aimed at decreasing these selection effects, and show results of applying our spin and shape models in detailed thermophysical modelling, simultaneously joining data from different infrared observatories.
14 October 2019
“Modeling cosmic acceleration through the equation of state”
dr Mariana Jaber Bravo
Currently, the Universe goes through an accelerated expansion, different observations have proven such fact: (SNeIa, BAO, CMB anisotropies, LSS formation, Weak Lensing). Even more, future projects and surveys are underway or being proposed to discover the underlying cause of this phenomena. The current cosmological paradigm, LCDM, models the dark energy (DE) component as a constant term that produces late time acceleration. However some degrees of tension have appeared among different data sets which has renewed the interest on alternative models that can provide an acceleration mechanism. Parametric approaches are a useful way to study alternative models for DE.
In this talk I present two different parametric forms for the equation of state for DE. The first is motivated by scalar field dynamics such as in quintessence models and recovers the widely used CPL equation but allows for a richer behavior. The second parametrization can reproduce a f(R)-like evolution with sub percent precision over the numerical solutions. In both cases the constraints using observations are discussed. I will also mention the ongoing work for using voids as an observable of large scale structure and test among different cosmological models.
7 October 2019
“Inhomogeneous Cosmology: A no-compromise application of general relativity to our real Universe, its challenges and advantages”
dr Mohammad Ahsan Nazer
The standard model of cosmology applies the Friedmann-Lemaı̂tre-Robertson-Walker (FLRW) exact solution of the Einstein equations to model the evolution of the Universe. This exact solution possesses rotational and translational symmetries and is used to estimate the age of the Universe, its expansion history and to obtain distance-redshift relations. Initially small violations of these symmetries are assumed to have given rise to the current structure of the Universe that includes galaxies, walls of galaxies and voids. The perturbed FLRW solution (metric) with a spatially flat background is then used to model the observed matter distribution with some limitations that are attributed to the perturbative approach itself. A more complete treatment of structure formation relies on Newtonian cosmological (N-body) simulations. It is not clear if other problems such as the tension between the present Hubble constant H0 value from supernovae experiments and the cosmic microwave background anisotropies is because of the perturbative approach or the non-applicability of the FLRW exact solution.
Inhomogeneous cosmology refers to the modelling approach in which the rotational and translational symmetries are abandoned at the cost of increasing complexity but with the potential benefit of removing some of the problems in standard cosmology. I argue that inhomogeneous cosmology is a “conservative” approach of applying General Relativity (GR) to the universe in which problems in structure formation, the Hubble constant tension, and the cause of the accelerated expansion are explained by adopting a “back to first principles” paradigm. I will first give an overview of the averaging and backreaction concepts in inhomogeneous cosmology and I will end with an account of our attempts to use the Relativistic Zeldovich Approximation (RZA) to improve N-body simulations of structure formation.
17 June 2019
“Comparing radio-loud Swift/BAT AGN with their radio-quiet counterparts”
Maitrayee Gupta (Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Warszawa)
Some AGN are known to be efficient producers of strong, relativistic jets which power the extended radio sources. Most spectacular in respect of powers and sizes are the radio sources associated with AGN hosted by giant elliptical galaxies. However even among them, the production of powerful jets is a very rare phenomenon and the unanswered question remains why it is so. Since relativistic jets are most likely powered by rotating BHs via the Blandford-Znajek mechanism, one might expect that the parameters deciding about efficient jet production are BH spins and magnetic fluxes. If their values are large, then the innermost portions of accretion flow should be affected by the jet production and this should be imprinted in their radiative properties. In order to verify whether this is the case, we compare the radiative properties of radio-loud (RL) and radio-quiet (RQ) AGN selected from the Swift/BAT catalog with similar BH masses and Eddington ratios. As we have found the only significant difference concerns the hard X-ray luminosities, which are about two times larger in radio-loud AGN than in radio-quiet AGN. One might speculate that this difference comes from having in RL AGN X-ray contribution not only from the innermost, hot portions of accretion flow, but also from a jet. However, this interpretation is challenged by our following findings: (1) hard X-ray spectra of RL AGN have similar slopes and high-energy breaks to those of RQ AGN; (2) hard X-ray radiation is to be in both RQ and RL AGN quasi-isotropic. Hence we argue that production of hard X-rays in the RL AGN is like in the RQ AGN, dominated by hot, central portions of accretion flows, while larger X-ray production efficiencies in RL AGN can be associated with larger magnetic fields and faster rotating BHs in these objects.
10 June 2019
“Historia astronomii wciąż potrafi zaskakiwać, czyli Edward Gresham i jego Astrostereon”
prof. dr hab. Jarosław Włodarczyk (IHN PAN, Warszawa)
Wyniki badań nad zapomnianym rękopisem, zachowanym w Bibliotece Bodlejańskiej w Oksfordzie i w londyńskiej Bibliotece Brytyjskiej, rzucają nowe światło na recepcję teorii heliocentrycznej w Anglii w epoce Shakespeare’a, na kontekst pierwszych teleskopowych obserwacji Księżyca, poprzedzających odkrycia Galileusza, czy wreszcie na kwestię pierwszeństwa w wymyślaniu astronomii księżycowej. Autorem tego rękopisu, zatytułowanego Astrostereon or the Discourse of the Falling of the Planet i spisanego w 1603 roku, jak również zawartych w nim oryginalnych pomysłów astronomicznych był astrolog i lekarz Edward Gresham (1565–1613) – postać nieznana badaczom dziejów astronomii i niemal zupełnie zapomniana przez historyków przełomu epok elżbietańskiej i jakubińskiej. W swoim wystąpieniu przedstawię najciekawsze kwestie, poruszane przez Greshama, i spróbuję wskazać, w jaki sposób wzbogacają one naszą wiedzę o drogach rozwoju astronomii początku XVII stulecia.
3 June 2019
“On planet frequency around giants”
prof. dr hab. Andrzej Niedzielski
Evolved stars, giants, are not the best targets in search for exoplanets due to their variability. However, these objects represent perfect laboratories to study the population of planets around intermediate-mass stars and star-planet interactions. One of the largest projects devoted to search for planet around evolved stars in the Pennsylvania-Toruń Planet Search (PTPS). In my talk I will present all radial velocity based searches for planets around evolved stars and a general summary of their results as well as the recent results of PTPS.
27 May 2019
“Konkurs na nazwy planet i inne projekty na stulecie IAU”
dr Krzysztof Czart (IAU NOC Poland)
W tym roku Międzynarodowa Unia Astronomiczna (IAU) obchodzi 100 lat swojego istnienia. Z tej okazji zorganizowała akcję o nazwie IAU100, w ramach której w trakcie całego roku prowadzone są projekty skierowane do różnorodnych grup odbiorców (członków IAU, miłośników astronomii, nauczycieli, uczniów, społeczeństwa). Jednym z nich jest konkurs na nazwy planet pozasłonecznych IAU100 NameExoWorlds, który wystartuje na początku czerwca. Każdy kraj otrzyma prawo nazwania jednej z planet i jej gwiazdy. W tym celu będą prowadzone krajowe konkursy. Inne przykłady działań w ramach IAU100 to Astronomy Translation Network, AstroVoices, globalne obserwacje Księżyca w 50. rocznicę załogowego lądowania na Srebrnym Globie. Z kolei Polskie Towarzystwo Astronomiczne przygotowuje akcję “Astronomers in Schools” (wizyty astronomów w szkołach).
20 May 2019
“Determining star formation rates in high-redshift galaxies from IRX-beta relation”
dr Maciej Koprowski
Precise determination of star formation rates for many galaxies at high redshifts is very difficult, as they often lack IR observations, sensitive to the starlight re- processed by dust. In order to account for this, one has to, therefore, utilize alternative methods, most popular of which involves estimating the energy re-emitted in the IR (infrared excess, IRX=LIR/LUV) based on the amount of reddening in the rest-frame UV (UV slope, β) via the so-called IRX-β relationship. Many works, however, seem to indicate that this local relation may not necessarily hold at high redshifts.
In this talk I will present the stacking analysis of a large sample of optically-selected Lyman-break galaxies (LBGs) in the JCMT SCUBA2 and Herschel SPIRE bands that was done in order to re-calibrate the IRX-β relationship at redshifts 3−5. I will show that at high redshifts, the average galaxy suffers from the dust attenuation law which is characteristic of local sources. I will also explain how different methods of estimating the UV slope, β, can cause the resulting relation appear flatter and therefore often consistent with the SMC-like attenuation law. In addition, I will show how the individual values of the IRX and β were calculated for a sample of 41 z~3 LBGs, detected in the recently-finished ALMA follow-up survey of the UDS SCUBA-2 sources. I will explain how the apparent scatter in the IRX-β plane is driven by the relative distribution of the stars and dust, as encoded in the shapes of the attenuation curves, as well as show how the shapes of the assumed attenuation curves affect the resulting stellar masses, as estimated via SED fitting. The results presented in this talk indicate that while, on average, star formation rates for high-redshift galaxies can be estimated from UV data alone, the values for the individual sources cannot be trusted in the absence of the IR data.
13 May 2019
“Young Stellar Objects in the Central Molecular Zone”
mgr Alya Amirah Azman
The Galactic Center (GC) environment provides unique and extreme conditions for star formation within the Milky Way. Candidate young stellar objects (YSOc) in the GC have previously been identified using Spitzer 24 micron emission. Star formation rates determined directly from YSOs counts are much higher than the value estimated from other methods. In addition, the YSOc distribution shows a puzzling asymmetry such that they are preferentially located at negative Galactic longitudes, while the molecular gas distribution is mostly concentrated to positive longitudes. To resolve the nature of these YSOc, we have conducted spectral line observations of these sources with APEX at 230GHz and characterized the dense gas associated with them. We also examine the far-infrared and submm properties of the YSOc using Hi-GAL and ATLASGAL survey data. Furthermore, using 70 micron data from Herschel Hi-GAL survey, we produce an independent catalog of YSOc. These confirm the known sites of star formation, as well as reveal new ones. Interestingly, based on our spectral line and dust continuum analysis, we find no evidence for the previously reported asymmetry. We conclude that some previous YSO catalogues were likely affected by contaminants, resulting in biased estimates of the star formation rate and its spatial distribution in the GC.
“VUV-Absorption cross section at high temperature and warm exoplanet atmosphere modeling”
mgr Ngân Lê
The discovery of extrasolar planets has been developed strongly during the past two decades. Spectroscopy observations during transit can allow us to detect the presence of molecules in the exoplanetary atmospheres. Chemical kinetics models have been used to interpret the observational data. However, the absorption cross-sections of many molecules used in the model are mainly at the room temperature while the exoplanets atmosphere is often very hot. In this talk, I will present a study concerning the evolution of VUV acetylene (C2H2) absorption cross-sections with temperature. The absorption cross-sections of C2H2 at 300, 500, and 600 K were fitted with Gaussian functions and then used to run the chemical kinetics model. Replacing the absorption cross-section of C2H2 at 300 K by the ones at higher temperature affects the molecular abundances in exoplanetary atmospheres.
6 May 2019
“Hen 3-160 – the first symbiotic binary with Mira variable S star”
Dr Cezary Gałan (Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Warszawa)
Symbiotic stars (SySt) are binary systems composed of a star in the late stage of evolution and a stellar remnant. The enhanced mass loss of the evolved star leads to strong interactions and the mass exchange what makes these systems useful laboratories for understanding binary evolution. There are a number of reasons to believe that many of these systems should containchemically peculiar giants, an extrinsic C (C-rich) and/or S (Zr-rich) stars. Observations, however, pointed to the deficit of such objects among SySt with ‘normal’ red giants. The problem remained not carefully investigated by analysis of the spectral line profiles and chemical abundance measurements so in the recent years we carry out the dedicated program to look for chemically peculiar giants in a large sample of SySt. I will present our results concerning one poorly studied so far but particularly interesting case of Hen 3-160, that turned out to be the first known symbiotic system with Mira variable S star. This object is reported in Belczynski et al.’s (2000) catalog as a symbiotic binary system with M7 giant donor. Using V- and I-band photometry collected over 20 years we have found that the giant is a Mira variable pulsating with 242.5-day period. The period-luminosity relation locates Hen 3-160 at the distance of about 9.4 kpc, and its Galactic coordinates (l=267.7∘, b=−7.9∘) place it ∼1.3 kpc above the disc. This position combined with relatively high proper motions indicates that Hen 3-160 has to be a Galactic extended thick-disc object. Our red optical and infrared spectra show the presence of ZrO and YO molecular bands that appear relatively strong compared to the TiO bands. We proposed that the giant in this system is intrinsic S star, enriched in products of slow neutron capture processes occurring in its interior during an AGB phase.
29 April 2019
“Building a disc galaxy after a major merger in Illustris”
Dr Nicolas Peschken
The major merger of two galaxies has long been thought to create elliptical galaxies due to the destruction of the progenitors in the violent relaxation phase of the merger. However in case of wet mergers it has been shown that accretion of gas after the merger can create a new disc component in the remnant, both from observations and from simulations of isolated galaxies. In our work we investigate this phenomenon in the larger frame of a cosmological context using the hydrodynamical simulation Illustris. We select a sample of major mergers creating disc galaxies in Illustris, and study their formation and evolution after the merger, and in particular the formation of the disc component in the remnant galaxy. We then derive from those cases the conditions necessary for the formation of a disc after a major merger.
15 April 2019
“Pomiary odległości i rotacja Galaktyki”
Prof. dr hab. Jacek Krełowski
Odległości wewnątrz naszej Galaktyki można mierzyć stosując metody: standardowego pręta (paralaksy trygonometrycznej), standardowej świecy (paralaksy spektroskopowej) lub pomiaru gęstości kolumnowej gazu międzygwiazdowego. Krzywa rotacji Drogi Mlecznej (przyjmowana za płaską poza orbitą Słońca) może być skonstruowana dzięki pomiarom odległości i prędkości radialnych dostatecznie odległych obiektów. Test płaskości krzywej rotacji wykonano bazując na obserwacjach międzygwiazdowych linii H i K zjonizowanego wapnia. Linie te pozwalają na pomiar zarówno odległości, jak i prędkości radialnej. Do testu użyto widm gwiazd OB z cienkiego dysku Galaktyki, zebranych spektrografem UVES. Widma pokazują wyraźnie, że momentalne prędkości radialne gwiazd nie nadają się do testu z racji krotności obserwowanych obiektów. Natomiast wysoka rozdzielczość spektrografu pozwala mierzyć prędkości radialne obłoków z dużą precyzją. Odległości wyznaczano albo z natężeń linii H i K albo z niedawno opublikowanych paralaks trygonometrycznych satelity Gaia. Te dwa rodzaje pomiarów najwyraźniej zgadzają się statystycznie, ale w indywidualnych obiektach mogą być znacząco różne. Uzyskane krzywe rotacji również zgadzają się statystycznie. Pojawił się tu bardzo ciekawy wynik: o ile prędkość orbitalna maleje na zewnątrz orbity Słońca (co można wytłumaczyć keplerowskim charakterem krzywej rotacji) o tyle maleje ona również ku centrum i to zjawisko pozostaje niezrozumiałe.
8 April 2019
“Lokalna skala odległości we Wszechświecie”
Dr hab. Dariusz Graczyk (Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Toruń)
Lokalna pozagalaktyczna skala odległości jest kalibrowana za pomocą trzech niezależnych punktów “zerowych”: odległości do galaktyki maserowej NGC 4258, paralaks trygonometrycznych galaktycznych cefeid oraz odległości do Wielkiego Obłoku Magellana (LMC). Odległość do LMC jest obecnie znana z dokładnością 1%, co pozwala na wyznaczenie parametru Hubble’a H0 z dokładnością lepszą niż 2%. Porównanie z globalną wartością H0 wyznaczoną z obserwacji mikrofalowego promieniowania tła (Planck+WMAP) oraz oscylacji akustycznych materii barionowej prowadzi jednak do znaczącej rozbieżności na poziomie 4.4sigma. Czy ta rozbieżność wskazywać może na “nową” fizykę rozciągającą się poza standardowy obecnie model kosmologiczny ΛCDM?
1 April 2019
“New picture of the Milky Way”
Dr hab. Paweł Pietrukowicz (Astronomical Observatory, University of Warsaw)
Milky Way is a complex system which exploration is hampered due to the presence of interstellar dust and the location of our Sun close to the Galactic plane. I will review the current knowledge on the structure and evolution of the Milky Way based on the most recent results obtained by large surveys.
25 March 2019
“Eclipsing binaries in multiple systems”
Dr hab. Wojciech Dimitrow (Institute Astronomical Observatory, Adam Mickiewicz University, Poznań)
Stars form in multiple systems. The statistics of stellar multiplicity provide constraints on the initial parameters of the stellar clusters formation. All zero age stars are members of binary or multiple systems. This is confirmed with observation and simulations of collapsing molecular clouds. Some of the multiples contain close eclipsing pairs. The photometric and spectroscopic observations of those pairs enabled us to obtain the absolute parameters with an accuracy of 1% or better. Over the last decade we observed five multiple systems. For most of them we detected a new components. We calculated the models for the eclipsing subsystems. The star with higher multiplicity, which we investigated is quintuple. The main instruments used in this program are small 0.5-m and 0.7-m telescopes equipped with echelle spectrographs, but we also used spectra from 2-m class telescopes.
18 March 2019
“Modeling energy-dependent propagation and dynamical effects of cosmic rays in galaxies”
Mgr Mateusz Ogrodnik
Recent theoretical and numerical studies incorporating cosmic rays (CRs) into global modeling of magnetized interstellar medium demonstrate that CRs play an important role in generation of large-scale galactic magnetic fields and, at the same time, in driving galactic winds. Cosmic-Ray-driven dynamos produce magnetic arms in galactic disks and large-scale helical magnetic fields in galactic halos.
A new element of our model is a population of CR electrons injected in SN remnants together with CR protons. I am going to present a novel implementation of energy dependent propagation of CR electrons in ”Cosmic Ray Energy SPectrum” (CRESP) module of PIERNIK MHD code. The overall propagation of cosmic rays is described by energy-dependent diffusion-advection equation, including adiabatic cooling and synchrotron losses of CR electrons. We use the CRESP module to study the propagation of CR electrons and their synchrotron emission in the magnetized interstellar medium of spiral galaxies. The resulting spatial distributions of gas, magnetic fields, and cosmic ray electrons are used to construct synthetic radio-maps of the modeled galaxies.
11 March 2019
“Obserwacyjne wskaźniki statusu ewolucyjnego mgławic planetarnych”
Dr Marcin Hajduk (University of Warmia and Mazury, Olsztyn)
Do badania ewolucji mgławic planetarnych tradycyjnie zastosowanie mają pomiary jasności i temperatury, lokujące te obiekty na diagramie HR. Pomiar jasności jest obarczony różnymi niepewnościami. Gwiazda emituje maksimum swojego promieniowania poza zakresem widzialnym. Oszacowania odległości czy ekstynkcji międzygwiazdowej dla mgławic planetarnych są niepewne. Z kolei jasność gwiazd centralnych jest silną funkcją masy, w wyniku czego niewielki błąd jasności propaguje się na duży błąd w wyznaczeniu masy i odpowiedniego toru ewolucyjnego. Bardzo dobrą obserwablą do badania gwiazd centralnych jest tempo zmian temperatury. Wielkość tą można wyznaczyć stosunkowo łatwo porównując stosunki strumieni linii mgławicowych czułych na temperaturę zmierzone w odpowiednim odstępie czasu. Ewolucja temperatury młodych gwiazd centralnych jest mierzalna w skali czasowej lat i dekad. Co ważne, wyznaczenie tempa zmiany temperatury nie zależy od odległości. Inną cechą gwiazd centralnych, mającą istotny wpływ na określenie ich statusu ewolucyjnego, jest ich podwójność. Według niektórych autorów ona jest główną przyczyną powstawania niesferycznych mgławic. Podczas seminarium przedstawię wyniki prowadzonych badań i przyszłe plany.
4 March 2019
“Waveplates on the sky: the origin of complex radio pulsar polarization”
Dr hab. Jarosław Dyks (Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Toruń)
Pulsar radio signals consist of two elliptical orthogonal polarization modes attributed to birefringence of magnetospheric plasma. In addition to regular noncoherent polarization effects expected for such combined signals, the radiation exhibits a number of astonishing complex phenomena, such as bifurcations of polarization angle tracks, half-orthogonal polarization angle jumps, different handedness of circular polarization in a single mode, orthogonal polarization mode jumps at maximum circular polarization, and others. The effects prove the importance of phase-sensitive coherent wave superposition in pulsar magnetosphere. First principle theoretical models (such as polarized ray tracing) were used to model the polarization, but they have not reached the level that allows us to reproduce or explain the data. I will show that empirical models are capable to interpret the effects in geometrical terms, both as a function of pulse longitude and frequency.
25 February 2019
“Modelowanie kształtu i parametrów rotacji planetoid w oparciu o dane fotometryczne”
Dr Przemysław Bartczak (Institute Astronomical Observatory, Adam Mickiewicz University, Poznań)
Planetoidy stanowią ważną grupę ciał w Układzie Słonecznym. Prowadzone badania nad ich własnościami fizycznymi wzbogacają naszą wiedzę na temat powstawania, budowy i ewolucji układów planetarnych. Prawidłowe wyznaczenie parametrów fizycznych i ich niepewności jest wyzwaniem dla astronomów od 120 lat. W czasie prezentacji przedstawiona zostanie nowa metoda oraz wyniki modelowania kształtu i parametrów rotacji.
21 January 2019
“Tidally induced bars in interacting galaxies”
Prof. Ewa Łokas (Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Warszawa)
I will talk about the interactions between galaxies and how they influence their dynamics and morphology. The presentation will focus on recent results of simulations following an interaction of two similar disky galaxies on unbound orbits. It turns out that the result of the interaction can be very different depending on the relative orientation of the galaxy’s internal spin and its orbital angular momentum. In the case of aligned spins and a sufficiently strong interaction, it can result in the formation of a tidally induced bar. I will discuss in detail the properties of such bars and the so-called buckling instability that occurs in them, when the bar becomes distorted out of the initial disk plane. I will present different measures of asymmetry in the edge-on view as well as kinematic signatures of buckling. I will demonstrate that tidally induced bars offer a unique possibility to obtain insight into the nature of buckling instability.
14 January 2019
“New types of transients in the era of all-sky surveys”
Dr Mariusz Gromadzki (Astronomical Observatory, University of Warsaw)
Last decade is a period of an extensive development of all-sky surveys, which reveal discovery of new types of transients such as Super Luminous Supernovae, Tidal Disruption Events and other rapidly evolving objects. In my talk I will present a brief review of this exciting topic.
7 January 2019
“On the origin of gravitational wave source”
Prof. Tomasz Bulik (Astronomical Observatory, University of Warsaw)
The recent detections of coalescences of compact object binaries in gravitational waves bring forward the question of the origin of such binaries. We review the basic properties of the known coalescences. These properties set quite strong constraints on the models of formation of merging binaries of compact objects. We discuss these constraints and briefly outline the major challenges that must be met in order to unravel the origin of these objects.
17 December 2018
“The integrability studies of selected systems in celestial mechanics”
Dr hab. Maria Przybylska, prof. UZ (Institute of Physics, University of Zielona Góra)
The problem of distinguishing between regular and irregular dynamics has a long history related to the development of the celestial mechanics. One can mention here the works of Poincaré on three body problem where chaos was first time observed. For detection of regular systems the Kovalevska-Painlevé method was the most popular for years. However, although using it many new cases have been found assumptions underlying it are not rigorous. Only recently very strong and rigorous necessary integrability conditions have been formulated using the differential Galois theory. Conditions of this type enable to select values of physical parameters, for which the dynamics may be regular. During the seminar, the applications of this theory to various systems with particular emphasis on the celestial mechanics systems will be shown. Among others two body problems in curved spaces, anisotropic Kepler problem, planar three body problem and generalised two fixed centers problem will be considered.
10 December 2018
“What have we learnt form oscillations of B-type stars?”
Prof. Jadwiga Daszyńska-Daszkiewicz (Astronomical Institute, University of Wrocław)
The main goal of asteroseismic studies is to obtain information on physical processes and conditions in stellar interiors that determine evolution and the final fate of stars. The most important ones are rotation, mixing processes, convection and opacities. High-precision space observations (MOST, CoRoT, Kepler, BRITE) have revolutionized our knowledge about many pulsators. For example, it appeared that in most (if not all) B-type pulsating stars both pressure (p) and gravity (g) modes are observed, i.e., they are hybrid pulsators of β Cep/SPB or SPB/β Cep type. This discovery has opened up a possibility of getting more stringent constraints on parameters of the model and theory because a simultaneous excitation of p and g modes offers probing stellar regions sensitive to various physical processes. On the other hand, the presence of high order g-modes in β Cep stars (M & 8M ) and p modes in SPB stars (M . 8M) is a challenging fact waiting for explanation because these modes are stable in all standard opacity models. This discovery proves some missing components or erroneous assumptions in our evolutionary calculations. I will present our results of seismic analysis of B-type main sequence pulsators. In particular, what we have learnt about stellar opacities, overshooting from the convective core and on internal rotation from these studies.
3 December 2018
“How to falsify CDM (and test its alternatives)?”
Dr Wojciech Hellwing (Center for Theoretical Physics, Polish Academy of Sciences)
While the Earth-base laboratories keep trying very hard to elucidate on the nature of the elusive dark matter particles the other very promising avenue to test and/or falsify potential dark matter candidates resides in astrophysical observations. In this context our own Galaxy – the Milky Way – with its unique set of satellites shows potential to serve as a extraterrestrial laboratory for dark matter. The very physical nature of dark matter particles and especially the differences between the main candidate, the neutralino of Cold Dark Matter (CDM), and its currently strongest competitor, the sterile neutrino of Warm Dark Matter candidate, may lead to significant differences in the properties of dwarf galaxies. Such objects are dominated (by mass) by their host DM haloes and therefore provide an unique view on the physical properties of DM. I shall discuss our recent efforts to use the state-of-the-art galaxy formation hydrodynamical simulation scheme of the EAGLE project as well as high-resolution Copernicus Complexio N-body simulations to study the galaxy formation of Milky Way like systems in CDM and WDM scenarios. Our results render new insights on potential ways to use astronomical observations for falsifying the CDM paradigm and testing its competitors.
26 November 2018
“History of astronomy in Toruń” (in Polish)
Dr Cecylia Iwaniszewska
19 November 2018
“PL SST – polski system wykrywania i śledzenia obiektów satelitarnych w przestrzeni wokółziemskiej” (in Polish)
Prof. Edwin Wnuk (Astronomical Observatory of UAM, Poznań)
Abstract (in Polish):
Od 2019 roku Polska jako kraj członkowski Europejskiego Konsorcjum EU SSA (Space Situational Awareness) rozpocznie świadczenie usług SST (Space Surveillance and Tracking). W związku z tym, od pewnego czasu trwają intensywne prace, których celem jest zbudowanie Polskiego Systemu PL SST, który w przyszłości zostanie rozszerzony do PL SSA.
SSA składa się z trzech następujących segmentów:
– Space Weather (SWE) – monitorowanie Słońca, wiatru słonecznego oraz ziemskiej magnetosfery, jonosfery i termosfery,
– Near-Earth Objects (NEO) – detekcja i monitorowanie ruchu orbitalnego obiektów naturalnych, takich jak planetoidy i komety, które mogą zbliżać lub zderzyć się z Ziemią,
– Space Surveillance and Tracking (SST) – detekcja, śledzenie i monitorowanie ruchu orbitalnego aktywnych i nieaktywnych satelitów oraz śmieci kosmicznych.
Polski System SST będzie składał się z Narodowego Centrum Operacyjnego (NOC), sieci kilkunastu teleskopów optycznych oraz stacji laserowej w Borowcu. Będzie ściśle powiązany z systemami EU SST i ESA SST oraz z europejskim centrum danych satelitarnych SATCEN. System PL SST, w pierwszym okresie działania, będzie świadczył dwie usługi dla EU SST: RE – Re-Entry oraz FR – Fragmentation, a później także CA – Collision Avoidance. Na potrzeby tych serwisów, a także na potrzeby krajowych odbiorców usług SST, będą wykonywane obserwacje wybranych obiektów satelitarnych, wyznaczane orbity tych obiektów oraz będzie tworzony i aktualizowany Katalog Satelitarny.
W referacie zostaną przedstawione aktualne informacje związane z tworzeniem systemu PL SST, w szczególności struktura organizacyjna i potrzeby softwarowe Centrum Operacyjnego. Opisane zostaną także krótko podstawowe serwisy SST, a także problemy związane z tworzeniem Katalogu Satelitarnego.
13 November 2018, 10.15
“Absorption processes in radio astronomy: Facilitating a unique discovery space”
Dr Joseph Callingham (ASTRON Netherlands Institute for Radio Astronomy)
One of the most common assumptions in radio astronomy is that the continuum spectrum of a radio source follows a simple power-law. Such an assumption is being challenged by the data being produced by the new sophisticated megahertz-sensitive telescopes and broadband gigahertz-receivers, as we can now sample the spectra of radio sources at a level of detail never before achievable. We are finding that a power-law description is inappropriate for many radio sources, particularly at low frequencies where absorption processes become significant. I will outline in my talk how low-frequency absorption processes provides us with a unique tool to test radio galaxy evolutionary models, mass loss scenarios of progenitor stars to supernovae, and a way to identify exoplanets. In particular, I will demonstrate that probing these absorption processes opens up an untapped discovery space for exotic objects that have been missed in more traditional spectral searches.
5 November 2018
“Constraints on the dark energy properties from observations of active galactic nuclei”
Prof. Bożena Czerny (Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Warszawa)
Dark energy is the greatest puzzle for physicists and astronomers. It is responsible for acceelerating expansion of the Universe. We need more astronomical probes to make sure we actually measure this phenomenon, and that we do it accurately. I propose to use quasars as dark energy tracers. Our main method is based on the determination of the delay between the quasar emission lines and the quasar continuum, which allows to measure directly the size of the emitting region as a light travel time. This size, as we showed in our innovative model of the formation mechanism of this region, depends almost exclusively on the absolute luminosity of a quasar. Knowing the absolute luminosity and measuring – which is simple – the observed luminosity and the redshift of every object we can locate every quasar in a Hubble diagram. For the data, we are using our own monitoring of selected quasars with the 11-m Southern African Large Telescope, as well as other available measurements done by other groups. Particularly attractive data wiill come from the future LSST (Large Synoptic Survey Telscope). The method is still under development but I will discuss the first results and the future prospects.
29 October 2018
“Star-planet tidal interactions with precise transit timing”
Dr Gracjan Maciejewski
Theoretical calculation and some indirect observations show that massive exoplanets on the tightest orbits – so called hot Jupiters – must undergo orbital decay due to tidal dissipation within their host stars. This orbital evolution could be observationally accessible through precise transit timing over a course of decades. Meter-class telescopes are recognised as excellent instruments for such follow-up observations. The rate of planetary in-spiralling may not only help us to understand some aspects of evolution of planetary systems, but also can be used as a probe of the stellar internal structure. Since 2017 we have run a regular observing campaign aimed at transit timing for a sample of the best candidates for in-falling planets. Among them there is WASP-12 b, transits of which exhibit pronounced departure from a linear ephemeris. New observations allow us to confirm the rapid decay rate for that planet and to place constraints on the tidal dissipation efficiency in other systems.
22 October 2018
“Studies of statistical isotropy of the cosmic microwave background”
Dr Paweł Bielewicz (Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Warszawa)
Studies of the cosmic microwave background (CMB) are today one of the most important pillars of observational cosmology. They provide information not only on the initial conditions of the Universe but also on scales comparable to the horizon of the observable Universe. This gives a unique opportunity to pose important questions about very fundamental assumptions made in the standard cosmological model such as statistical isotropy and Gaussianity of the initial fluctuations. This also allows to test deviations from the statistical isotropy predicted in models of the Universe with multi-connected topology and deviations generated by gravitational lensing of the CMB, predicted in the standard cosmological model. Considerable effort spent on analyzing the statistical properties of the CMB maps has resulted in several reports of a breaking of statistical isotropy at large angular scales and detection of the gravitational lensing effect. I will review these studies paying special attention to the results obtained recently for the state-of-the-art data from the Planck satellite.
15 October 2018
“Radio emission of galaxy groups: current knowledge and future prospects”
Dr Błażej Nikiel-Wroczyński (Astronomical Observatory, Jagiellonian University)
Existence and importance of non-thermal radio emission – and underlying magnetic fields – in galaxy groups is a topic still scarcely studied. While not much observational evidence has been gathered, the recent theoretical predictions, suggesting overall importance of non-thermal processes in galaxy groups, and possibility to host detectable magnetic fields call for a large-scale effort to provide such data. I will present the efforts undertaken to fulfill this task that made use of the LOFAR Two Metre Sky Survey data, and describe the preliminary results.
8 October 2018
“A search for z>5 quasars in OGLE”
Dr hab. Szymon Kozłowski (University of Warsaw)
I will discuss why finding and studying distant quasars is important, how it is related to cosmology and to our understanding of the Universe. The second part of my talk will be devoted to methods that have been used to search for distant data in the OGLE and WISE data.
1 October 2018
“The mysterious age invariance of the planetary nebula luminosity function bright cut-off”
Prof. Krzysztof Gęsicki
Planetary Nebula forms when a sun-like star ejects and ionizes much of its envelope, and the prodigious amounts of energy is emitted in several emission lines. From the line-flux distribution the Planetary Nebula Luminosity Function can be compiled. It increases towards faint-end as expected for an expanding spherical shell. However at the bright-end there exists an unexplained cut-off. Interestingly, the cut-off value appears to be nearly the same for stellar populations of different ages, and, despite the lack of understanding, became a powerful extragalactic distance estimator. I will show that new evolutionary tracks of low-mass stars are capable to explain the decades-old mystery.
18 June 2018
“Science highlights from H.E.S.S.”
Prof. Bronisław Rudak (Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Toruń)
The High Energy Stereoscopic System (H.E.S.S.) is an array of five imaging atmospheric Cherenkov telescopes operating in Namibia. Its observational performance has lead to many discoveries in the domain of Very High Energy astronomy. The talk will present the most important results obtained recently with H.E.S.S. in galactic and extragalactic astronomy as well as in astroparticle physics.
11 June 2018
“Search for unusual objects in AllWISE Sky Survey”
Dr Aleksandra Solarz (National Centre for Nuclear Research, Warsaw)
Wide-angle photometric surveys of previously uncharted sky areas or wavelength regimes will always bring in unexpected sources whose existence and properties cannot be easily predicted from earlier observations. Such objects can be efficiently sought for with novelty detection algorithms. I will present an application of such a method, called one-class support vector machines (OCSVM), to search for anomalous patterns among sources preselected from the mid-infrared AllWISE catalogue covering the whole sky. OCSVM successfully finds artefacts, such as objects with spurious photometry due to blending, but most importantly also real sources of genuine astrophysical interest. Among the latter, OCSVM has identified a sample of heavily reddened AGN/quasar candidates distributed uniformly over the sky and in a large part absent from other WISE based AGN catalogues. It also allowes to find a specific group of sources of mixed types, mostly stars and compact galaxies. By combining the semi-supervised OCSVM algorithm with standard classification methods it will be possible to improve the latter by accounting for sources which are not present in the training sample but are otherwise well-represented in the target set.
4 June 2018
“Massive stars formed in atomic hydrogen reservoirs”
Dr Michał Michałowski (Astronomical Observatory, Adam Mickiewicz University, Poznań)
I will discuss the process of gas inflow on galaxies and subsequent fuelling of star-formation. Using ATCA HI observations I will show that galaxies with anomalous local metallicity decrements (gamma-ray burst host galaxies) have substantial atomic gas reservoirs, and are possibly deficient in molecular gas. This suggests that star formation in these galaxies may be fuelled by recent inflow of metal-poor atomic gas. This is controversial, but can happen in low-metallicity gas near the onset of star formation because cooling of gas (necessary for star formation) is faster than the HI-to-H2 conversion.
30 May 2018, 11:15, Piwnice, Department Of Radioastronomy seminar room
Special Astrophysics Seminar
“Spectral modeling of the WR147 binary system”
Dr Blagovest Petrov(Institute of Astronomy, Bulgarian Academy of Sciences)
28 May 2018
“Wiatry galaktyczne napędzane promieniowaniem kosmicznym”
Prof. dr hab. Michał Hanasz
Promieniowanie kosmiczne złożone z elektronów, protonów i cięższych jąder atomowych przyspieszane jest do relatywistycznych energii w pozostałościach supernowych. Według standardowych oszacowań około 10% energii wybuchów supernowych przetwarzana jest w energię naładowanych cząstek. Sumaryczna energia zgromadzona w postaci promieniowania kosmicznego jest wystarczająca do napędzania wiatrów galaktycznych. W galaktykach dyskowych w powstawaniu wiatrów uczestniczy również gorący gaz podgrzewany przez fale uderzeniowe pozostałości supernowych. Własności fizyczne wiatrów termicznych i wiatrów napędzanych promieniowaniem kosmicznym różnią się istotnie. Modele oparte na symulacjach numerycznych pokazują, że dzięki udziałowi promieniowania kosmicznego wiatry galaktyczne są gęstsze od wiatrów termicznych oraz są chłodniejsze, gładsze i wolniejsze. Modele pokazują również, że wiatry napędzane promieniowaniem kosmicznym prowadzą do powstania spiralnych struktur pola magnetycznego w galaktycznym halo, które obserwowane w zakresie radiowym ujawniają sie jako struktury o kształcie litery „X”.
21 May 2018
Dr Eva Villaver (Universidad Autónoma de Madrid, Spain)
A planetary system evolves hand-by-hand with its host star. The planet can experience orbital changes, extreme evaporation, accretion and substantial surface temperature modifications. The star, if the planet gets engulfed, can increase its rotational speed, modify its chemistry, and even generate magnetic fields. In this talk, I will summarize what are we learning from the way planets and stars interact as the star leaves the main sequence.
14 May 2018
“Repozytorium Surowych Danych Astronomicznych Online”
Dr Dominik Wóltański
RSDAO to baza obserwacji astronomicznych utrwalonych oryginalnie na materiałach światłoczułych, a w ostatnim czasie zdigitalizowanych. Zgromadzony w repozytorium materiał obserwacyjny został zebrany przez astronomów UMK w okresie od powstania obserwatorium astronomicznego w Piwnicach w latach 40-tych do lat 90-tych XX wieku z pomocą teleskopów optycznych. W ramach seminarium przedstawię wyniki przeprowadzonych w ostatnich latach prac, mających na celu udostępnienie archiwalnych obserwacji astronomicznych pracownikom Centrum Astronomii i międzynarodowemu środowisku astronomicznemu w ramach wirtualnego obserwatorium.
9 May 2018, 11:15, Institute of Physics, Center of Quantum Optics, Toruń
Special Astrophysics Seminar
“Airborne infrared astronomy with SOFIA”
Prof. Hans Zinnecker (Deutsches SOFIA Institut, University of Stuttgart, Germany oraz Universidad Autonoma de Chile, Santiago, Chile)
SOFIA, short for Stratospheric Observatory for Infrared Astronomy, is a 2.7m telescope flying on a Boeing 747SP at altitudes of 12-14km, to detect and study mid- and far-infrared radiation that is blocked by water vapor in the earth’s atmosphere and cannot reach the ground. It is currently the only platform for astronomical observations in the far-infrared (30-300 microns), except for balloon-borne telescopes. The far-infrared is the key wavelength regime for studying the energy balance in the interstellar medium (heating and cooling of interstellar gas and dust) and the processes in cold dense gas clouds related to star formation (collapse, outflows, etc). About half of the total luminosity in the universe emerges in the far-infrared.
Although a bilateral project (80:20) between USA (NASA/USRA) and Germany (DLR/DSI), SOFIA is open for proposals from the world-wide astronomical community at large. It addresses many science questions that ESA’s successful but now extinct Herschel Observatory (far-infrared satellite 2009-2013) has left unanswered and offers observational opportunities similar to and beyond Herschel. SOFIA also has many synergies with large ground-based mm and submm telescopes and telescope arrays, such as ALMA in Chile or NOEMA in France. The mobility of SOFIA (to fly anywhere anytime on the planet) uniquely allows to observe occultation events by solar system objects, such as Pluto.
In my presentation, I will describe a glimpse of SOFIA science highlights and discoveries in its first few years of operation (since 2012), including observations of star formation (gravitational contraction of protocluster clouds) and of our Galactic Center (the circumnuclear disk around the black hole), both in far-infrared lines and continuum. SOFIA spectroscopic observations of interstellar cloud dynamics using rotational transitions in key molecular lines (NH3, H20, H2) with high spectral resolution will be described, as well as the diagnostics of the surface cooling of UV-illuminated clouds through the very strong [OI] (63mu) and [CII] (158mu) fine structure lines. Time permitting, I will also discuss the latest new instrumentation (enabling far-infrared polarimetry and cloud magnetic field observations).
SOFIA normally flies out of California, but once a year also deploys to the Southern Hemisphere (usually to Christchurch, New Zealand), benefitting from the excellent wintertime stratospheric conditions to study the interstellar medium and the cold star forming universe in the rich southern skies.
23 April 2018
“On the dynamical history of the interstellar object ’Oumuamua”
Prof. dr hab. Piotr Dybczyński (Astronomical Observatory, Adam Mickiewicz University, Poznań)
1I/2017 U1 ’Oumuamua is the first interstellar object recorded inside the Solar System. We try to answer the main question: where does it come from? To this aim we searched for close encounters between ’Oumuamua and all nearby stars with known kinematic data during their past motion.We had checked over 200 thousand stars and found just a handful of candidates. If we limit our investigation to within a 60 pc sphere surrounding the Sun, then the most probable candidate for the ’Oumuamua parent stellar habitat is the star UCAC4 535-065571. However GJ 876 is also a favourable candidate. Moreover, the origin of ’Oumuamua from a much more distant source is still an open question. Additionally, we found that the quality of the original orbit of ’Oumuamua is accurate enough for such a study and that none of the checked stars had perturbed its motion significantly.
16 April 2018
“BRITE i UVSat: teraźniejszość i przyszłość polskich misji satelitarnych”
Prof. dr hab. Andrzej Pigulski (Instytut Astronomiczny, Uniwersytet Wrocławski)
Abstract (in Polish):
Trwająca misja BRITE przynosi z każdym tygodniem coraz ciekawsze wyniki naukowe. Kilka z nich przedstawię w szczegółach. Misja BRITE pokazała, że możliwe jest uzyskanie precyzyjnej fotometrii za pomocą nanosatelitów. Druga część seminarium poświęcona będzie nowej koncepcji niewielkiego satelity UVSat, niosącego na pokładzie podwójny teleskop, jeden przeznaczony do fotometrii w szerokim polu w ultrafiolecie, drugi – do podobnej fotometrii w dziedzinie widzialnej. Przedstawię potencjalne cele naukowe takiej misji oraz kierunki badań, które można będzie dzięki danym z takiego satelity rozwijać.
9 April 2018
“Optyczne obserwacje sztucznych satelitów Ziemi”
dr Krzysztof Kamiński (Astronomical Observatory, Adam Mickiewicz University, Poznań)
Abstract (in Polish):
W promieniu do 40 tys. km od powierzchni Ziemi znajduje się wg. publicznie dostępnego katalogu satelitarnego USSTRATCOM ok. 17000 obiektów o rozmiarach powyżej 10 cm. Tylko kilka procent z nich stanowią użyteczne, działające sztuczne satelity. Pozostałe zaliczane są do tzw. śmieci kosmicznych. Szacunki wskazują ponadto na kilkaset tysięcy obiektów o rozmiarach od 1 do 10 cm. Ze względu na stale rosnącą liczbę tych obiektów, a w konsekwencji rosnące ryzyko katastrofalnych zderzeń, rozwijane są w Europie, m. in. w ramach programów opcjonalnych ESA oraz konsorcjum EU SST, systemy monitoringu przestrzeni wokółziemskiej. Wiodącym dotychczas rozwiązaniem w dziedzinie wykrywania i śledzenia sztucznych satelitów Ziemi znajdujących się na niskich orbitach są wyspecjalizowane systemy radarowe. W ostatnich latach dokonał się jednak ogromny postęp w dziedzinie obserwacji optycznych. Nowe detektory, montaże i systemy optyczne pozwalają na znaczne zwiększenie wydajności pojedynczego instrumentu, a technologie takie jak kamery event-based mogą umożliwić detekcję satelitów w ciągu dnia. Najnowszy projekt instrumentalny Obserwatorium Astronomicznego UAM jest próbą weryfikacji, czy możliwe jest stworzenie kompletnego systemu śledzenia sztucznych satelitów Ziemi opartego głównie, a być może wyłącznie, o sensory optyczne.
26 March 2018
“In search for green valley… and other news from the Universe at z~1”
Prof. Agnieszka Pollo (National Centre for Nuclear Research)
I present the most recent results from the VIMOS Public Extragalactic Redshift Survey (VIPERS). VIPERS – with its ~ 90,000 spectroscopically measured galaxies, a large volume (5 x 10^7 h^(-3) Mpc^3), and an effective spectroscopic sampling > 40% – can be considered the state-of-the-art counterpart of “local” (z<0.2) cosmological surveys but targetting the epoch at z \sim 1. I will summarize our new findings on the properties of galaxies and large scale structure emerging from our analyses of these data. How different were galaxies 8 bln years ago in comparison to their descendants we find in our local Universe? Did green valley ever exist? What are the properties of the 3D cosmic structure emerging from VIPERS measurements and what can they tell us about the properties of dark energy? And, most interestingly – what challenges still await us?
19 March 2018
“Connecting light and dark side of the Universe”
Dr. Anna Durkalec (National Centre for Nuclear Research)
Studies at low and intermediate redshift ranges show that the relation between the luminous structure and underlying dark matter distribution is not straightforward and depend on the various properties of galaxy population. Naturally one would like to extend these studies of the luminous-dark matter relations to the high redshift ranges (z>2) in order to improve our understanding of the evolution of the universe structure.
During my seminar I will present the recent attempts to describe the large scale structure of the universe in early epochs of its evolution (z>2). In this context I will demonstrate my study of the dependence of galaxy clustering on luminosity and stellar mass in the redshift range 2 < z < 3.5 using spectroscopic data from the VIMOS Ultra Deep Survey (VUDS).
I will show the series of my recent results quantified using a power-law approximation of the correlation function and in the framework of the five parameter HOD (Halo Occupation Distribution) model, which indicate that at z~3 the correlation length, and all HOD characteristic masses depends on the luminosity and stellar mass – the bright and most massive galaxies are the ones that are the most strongly clustered and are likely to occupy the most massive dark matter haloes. I will conclude with the presentation of my measurements of the large scale galaxy bias and stellar-to-halo mass relation at high redshift.
12 March 2018
“Young Stellar Objects in the Outer Galaxy”
prof. Ryszard Szczerba (CAMK PAN Toruń)
We have initiated a systematic study of star formation in the Outer Galaxy to uncover the population of Young Stellar Objects (YSOs) in these previously unstudied clouds and investigate the impact of the environment on the star formation process. In my talk I would like to present results from analysis based on the data from the “Spitzer Mapping of the Outer Galaxy” survey (SMOG; PI Sean Carey) that covered ∼24 deg2 region in the Outer Galaxy: l = (102o, 109 o), b = (-0.2 o, 3.2 o) in the IRAC 3.6–8.0 μm and MIPS 24 μm bands. The analyzed data have been combined with the infrared (IR) data from the 2MASS and WISE. We have selected YSO candidates among IR excess sources, and then applied a series of filters to remove various populations of other sources. The method gave as about 1800 Class I YSOs and about 3000 Class II YSOs, for 36% of which we were able to determine kinematic distances using Canadian Galactic Plane Survey in CO (J=1-0) transition. What is more, we have performed an additional search of YSO candidates among sources with the WISE counterparts by using an automated source identification scheme based on Machine Learning algorithms. We have compared both methods and find that not only they are complementing each other, but also allow us to identify YSO candidates, which are missed by classical color-color based selections.
8 March 2018, 11:15
Special Astrophysics Seminar
“Dicke’s superradiance in astrophysics: maser flares and fast radio bursts”
Dr Fereshteh Rajabi (University of Waterloo, Canada)
Since its introduction by R. H. Dicke in 1954 and its first experimental verification nearly 20 years later, superradiance has become, and still is, a very active field of research in the quantum optics community. Although it has remained unnoticed by the astrophysics community until very recently, evidence has since been uncovered for the occurrence of superradiance in the interstellar medium. In this presentation, I will start by giving a brief description of the physics underlying Dicke’s superradiance and show how this quantum mechanical entanglement phenomenon can provide a simple framework for explaining the flaring of some maser sources. I will also briefly discuss how superradiance could help in elucidating the nature of fast radio bursts, a task perceived by some as being of one of the most pressing problems in astrophysics.
5 March 2018
“Red passive galaxies: when did they form?”
dr Małgorzata Siudek (National Centre for Nuclear Research)
Why some today’s galaxies are spiral and other elliptical? Why some are star-forming, while others have been “red and dead” already for some time? While we already seem to have a general scenario of the evolution of different types of galaxies, a complete and satisfactory understanding of the processes that led to the formation of all the variety of today’s galaxy types is still beyond our reach.
To solve this problem, we need both large data sets reaching high redshifts, and novel methodologies for dealing with them.
In my presentation, I will show results based on the data from the VIMOS Public Extragalactic Redshift Survey (VIPERS) – the largest redshift survey at z~1 so far. I am going to discuss star formation histories of the largest population of red passive galaxies ever analyzed for z>0.5, and I will present a novel method of galaxy classification, based on machine-learning techniques, revealing the true complexity of galaxy population found at z~1.
26 February 2018
“Co w Krabie piszczy?”
dr Agnieszka Słowikowska
Podczas mojego seminarium opowiem o najnowszych rentgenowskich obserwacjach polarymetrycznych Mgławicy Krab i porównam je z wynikami otrzymanymi w zakresie optycznym. Zaprezentuję wyniki obserwacji polarymetrycznych pulsara Krab w zakresie radiowym, optycznym i rentgenowskim. Przedstawię również wyniki badań polarymetrycznych w optycznym zakresie widma innych pulsarów. Dopiero teraz istnieje możliwość dokładnego zbadania spolaryzowanego promieniowania pulsarów optycznych takich jak Geminga czy B0656+14. Wyniki te są kluczowe dla modelowania przewidywanej polaryzacji rentgenowskiej tych źródeł. Podobnie jak jest to robione na przykładzie optycznych danych pulsara i mgławicy Krab, które są wykorzystywane do symulacji obserwacji budowanego polarymetru rentgenowskiego XIPE (X-ray Imaging Polarimetry Explorer).
22 January 2018
“Pogoda kosmiczna (SWE)”
prof. Paweł Rudawy (Instytut Astronomiczny Uniwersytetu Wrocławskiego)
Poznanie zjawisk opisywanych jako pogoda kosmiczna (SWE) jest jednym z kluczowych składników programu “Monitorowanie Sytuacji w Przestrzeni Kosmicznej” (SAA) Europejskiej Agencji Kosmicznej. SWE obejmuje monitorowanie i prognozowanie aktywności Słońca oraz zjawisk indukowanych w przestrzeni międzyplanetarnej, włącznie z ziemską magnetosferą i jonosferą a także badanie i prognozowanie wpływu tych procesów na zjawiska klimatyczne, środowiskowe oraz aktywność społeczną i technologiczną człowieka. Podczas spotkania postaram się naszkicować podstawowe procesy heliofizyczne generujące lub wpływające na stan przestrzeni międzyplanetarnej, niektóre zjawiska na Ziemi wywoływane przez SWE a także obecny stan badań w tej dziedzinie w Polsce.
15 January 2018
„Projekt CREME – Comprehensive Research with Echelles on the Most interesting Eclipsing binaries”
dr Krzysztof Hełminiak (CAMK Toruń)
Projekt CREME jest dużym obserwacyjnym przeglądem rozdzielonych zaćmieniowych układów podwójnych za pomocą spektrografów wysokiej rozdzielczości. Celem projektu jest wyznaczenie dla kilkuset obiektów jak najbardziej kompletnego zestawu precyzyjnych parametrów gwiazdowych, w tym mas, promieni, jasności, temperatur efektywnych czy metaliczności.
W szczególności skupiamy się na układach zaćmieniowych ze składnikami należącymi do słabo zbadanych i stosunkowo nielicznych klas gwiazd, takich jak gwiazdy o bardzo małej lub bardzo dużej masie, olbrzymy, gwiazdy przed ciągiem głównym, czy układy wielokrotne. Interesujące dla nas są także takie pary, dla których parametry można wyznaczyć z ekstremalnie wysoką precyzją (< 0.5 %). W swoim wystąpieniu przedstawię historię projektu, jego obecny status, ciekawsze wyniki oraz plany na przyszłość.
8 January 2018
„Pulsary z maksimum energii w widmie około 1 GHz”
dr hab. Wojciech Lewandowski (Instytut Astronomii im. profesora Janusza Gila, Uniwersytet Zielonogórski)
Fale radiowe emitowane przez pulsary w czasie swej propagacji do obserwatora ulegają kilku dobrze znanym zjawiskom zachodzącym w zjonizowanym ośrodku międzygwiazdowym: dyspersji międzygwiazdowej, rozpraszaniu sygnały radiowego oraz scyntylacjom. Jest jednak jeszcze jedno zjawisko, które przez długi czas było pomijane: swobodno-swobodna absorpcja termiczna na elektronach ośrodka międzygwiazdowego. Zjawisko to było uznawane za istotne wyłącznie na bardzo niskich częstościach radiowych (około 100 MHz i poniżej), jednakże odkrycie nowej grupy pulsarów wyraźnym maksimum energii na częstotliwościach około 1 GHz (ang. gigahertz-peaked spectra, GPS) zmusiło nas do zrewidowania tego sposobu myślenia.
Na chwilę obecną znamy około 30 pulsarów typu GPS (w tej liczbie znajdują się też 3 z 5 znanych radio-magnetarów). Większość z tych obiektów znajduje się w nietypowych lokalizacjach: wewnątrz mgławic będących pozostałościami po wybuchach supernowych, mgławic wiatru pulsarowego, czy tez wewnątrz gęstych obszarów H II. Nasze badania wykazały, że w pewnych specyficznych sytuacjach tego typu otoczenia pulsarów mogą być źródłem absorpcji termicznej na tyle silnym, by powodować obserwowane załamanie kształtu widma radiowego. Tego typu badania pozwolą nam lepiej przygotować się na interpretację wyników odkryć/obserwacji pulsarów za pomocą nowych instrumentów (takich jak np. SKA). Dodatkowo, mogą przyczynić się do rozwiązania kilku niewyjaśnionych zagadek – jak np. dlaczego nie widzimy żadnego spośród setek pulsarów których istnienia spodziewamy się w samym centrum Drogi Mlecznej?
18 December 2017
“Działalność Polskiego Towarzystwa Astronomicznego”
dr Krzysztof Czart
Do statutowych celów Polskiego Towarzystwa Astronomicznego (PTA) należy popieranie rozwoju nauk astronomicznych, ich dydaktyki i popularyzacji w społeczeństwie. Realizowane jest to w różnorodny sposób, od inicjatyw skierowanych bezpośrednio do astronomów, po projekty dla ogółu społeczeństwa.
Inicjatywami najbardziej znanymi i o największej skali oddziaływania są czasopismo i portal “Urania – Postępy Astronomii” oraz cykl programów telewizyjnych “Astronarium”. PTA prowadzi jednak dużo więcej projektów. Angażuje się w ogólnopolskie konkursy dla młodzieży (Olimpiada Astronomiczna, OMSA i inne), przyznaje certyfikat jakości dla planetariów, prowadzi coroczny konkurs na udział w obozie astronomicznym Europejskiego Obserwatorium Południowego (ESO) dla młodzieży, jest obecne na festiwalach nauki, astropiknikach. Najnowszą rozwijaną obecnie inicjatywą jest AstroGPS.pl – aplikacja mobilna z bazą wszystkich wydarzeń związanych z astronomią i kosmosem, które odbywają się w Polsce.
Z kolei w dziedzinie naukowej, PTA organizuje konferencje, warsztaty, przyznaje nagrody, czy wydaje serię publikacji konferencyjnych.
W trakcie seminarium przedstawiony będzie przekrój różnych działań PTA, pokazany ich zasięg oddziaływania oraz obszary, w które mogą włączyć się na przykład doktoranci i studenci astronomii.
11 December 2017
„Czarne dziury w Drodze Mlecznej i w centrach galaktyk”
dr hab. Łukasz Wyrzykowski (Obserwatorium Astronomiczne UW)
Zjawiska tymczasowe niosą informacje o aspektach Wszechświata, o których w innych sposób nie możemy się dowiedzieć. Najlepszym przykładem są niedawne detekcje sygnału w falach grawitacyjnych: te bardzo krótkotrwałe zjawiska złączenia się obiektów zwartych wykazały istnienie populacji czarnych dziur o masach kilka razy większych niż największe znane wcześniej gwiazdowe czarne dziury. Podobnie zwykłe i powszechne już zjawiska supernowych pozwoliły na wykrycie przyspieszającej ekspansji Wszechświata. Wykrywanie astronomicznych zjawisk tymczasowych weszło obecnie w złoty wiek, gdyż jest przeprowadzane na szeroką skalę przez liczne przeglądy, które regularnie skanują niebo w celu wykrycia nowych obiektów, których nie było tam podczas poprzedniej obserwacji.
W moim seminarium przedstawię wykorzystanie zjawisk tymczasowych takich jak soczewki grawitacyjne oraz zjawiska rozerwań pływowych do badań populacji czarnych dziur w Drodze Mlecznej oraz w centrach innych galaktyk. Przedstawię wstępne wyniki z poszukiwania soczewkujących czarnych dziur z projektów OGLE i Gaia. Zaprezentuję również przykłady zjawisk rozerwań pływowych gwiazd, wskazujące na czarne dziury w centrach galaktyk oraz nowe rodzaje zjawisk związanych z AGNami. Na koniec przedyskutuję możliwości poszukiwań średnio-masywnych czarnych dziur za pomocą obu tych metod.
4 December 2017
„Analysis of Infrared features of PAH’s”
Emily Kosmaczewski (Fulbright Research Fellow, Obserwatorium Astronomiczne Uniwersytetu Jagiellońskiego)
I will present on the importance of tracing infrared features in interstellar medium and in the host galaxies of young radio sources. Specifically, I will show the breakdown of polycyclic aromatic hydrocarbon (PAH) infrared emission features, the analysis and fitting of such features, the importance of certain features as tracers for star activity, as well as key correlations in the analysis of ISM. I will briefly discuss how this analysis can be used for other systems containing cold dust.
27 November 2017
„Near-field VLBI in the context of planetary and space science”
Leonid Gurvits (Joint Institute for VLBI ERIC and Delft University of Technology, The Netherlands)
A spacecraft emitting radio signals can be treated as a point-like target by VLBI systems. The latter offer an unsurpassed precision in measuring lateral celestial coordinates of a radio source. However, “traditional” astronomical VLBI systems are based, among other things, on the assumption that the target is infinitely far away, i.e. is located in the “far field”. The Fraunhofer limit defines the “border” between “far field” and “near filed”. For all practical VLBI spacecraft tracking applications, the distance to the target is well within the Fraunhofer limit. Thus, “traditional” VLBI algorithms must be modified for estimating lateral coordinates of a spacecraft.
The value of “near-field” VLBI for planetary and space science has been appreciated since the 1970s. A number of planetary and space science missions benefited from spacecraft VLBI tracking. The technique offered sub-milliarcsecond “positioning” of spacecraft on the celestial sphere. For the ESA’s Huygens Probe, this translated into ~1 km linear precision at the distance to Titan. Recently the technique has been demonstrated “in action” for the ESA’s Venus Express and Mars Express missions. The technique is also accepted as a Planetary Radio Interferometry and Doppler Experiment (PRIDE) for the ESA’s Jupiter Icy Satellites Explorer (JUICE) as a multi-disciplinary enhancement of the scientific suite of the mission, which will provide precise measurements of spacecraft lateral coordinates, radial velocity and its derivatives. The presentation will offer an overview of major approaches to near-field VLBI applications in planetary and space science toward achieving “lateral positioning” of planetary probes relative to ICRF background extragalactic radio sources with the accuracy of 100 to 10 microarcseconds.
20 November 2017
“GW170817: pierwsza detekcja fal grawitacyjnych pochodzących z układu podwójnego gwiazd neutronowych”
dr hab. Michał Bejger (CAMK Warszawa)
Opowiem o pierwszej, przełomowej obserwacji fal grawitacyjnych emitowanych podczas ostatnich sekund życia układu podwójnego gwiazd neutronowych, zarejestrowanych przez globalną sieć detektorów LIGO-Virgo, oraz o powiązanych z tą detekcją obserwacjami fal elektromagnetycznych pochodzących z krótkiego błysku gamma, poświaty rentgenowskiej, optycznej kilonowej itd. Wspólne obserwacje fal grawitacyjnych i elektromagnetycznych oznaczają prawdziwy początek ,,astronomii wieloaspektowej” (multi-messenger astronomy). Wyniki uzyskane z tych obserwacji to m.in. pierwszy pomiar tempa rozszerzania się Wszechświata przy pomocy ,,standardowej syreny”, niezależny od tradycyjnych drabin odległości, ograniczenia na równanie stanu materii gęstej, z której składają się gwiazdy neutronowe, oraz wyznaczenie prędkości propagacji fal grawitacyjnych.
13 November 2017
„Nowe perspektywy satelitarnej i naziemnej diagnostyki radiowej”
prof. Hanna Rothkaehl (Centrum Badań Kosmicznych PAN)
Diagnostyka fal radiowych zlokalizowana zarówno na powierzchni Ziemi jak też, na pokładach satelitów w przestrzeni kosmicznej może być doskonałym narzędziem do diagnostyki lokalnych właściwości plazmy kosmicznej oraz odległych radiowych źródeł pozagalaktycznych. Magnetosfera-jonosfera-termosfera to obszar przestrzeni okołoziemskiej silnie modyfikowany zarówno przez topologie i zmienność pól magnetycznych i elektrycznych, jak też strumieni przenikających cząstek wiatru słonecznego, a także szeregu drobnoskalowych procesów zachodzących w plazmie kosmicznej. Diagnostyka tych obszarów za pomocą nowatorskich technik diagnostyki radiowej pozwoli lepiej poznać fundamentalne zjawiska zachodzące w przestrzeni kosmicznej jak też skonstruować modele aplikacyjne które zostaną wykorzystane w programie Pogoda Kosmiczna jak też, przysłużą się do konstruowania korekt dla obserwacji radioastronomicznych. Celem prezentacji będzie prezentacja dotychczasowych rezultatów eksperymentów satelitarnych w zakresie diagnostyki radiowej przeprowadzonych przez CBK PAN oraz ukazanie nowych możliwości badawczych radioteleskopu LOFAR.
6 November 2017
Cagliari 336. Sympozjum Międzynarodowej Unii Astronomicznej – nowości w badaniach maserowych
dr hab. Anna Bartkiewicz, dr Paweł Wolak oraz doktoranci Mateusz Olech i Rafał Sarniak
Sympozjum “Astrophysical masers: unlocking the mysteries of the universe” odbyło sie we Włoszech na Sardynii na początku września br. Przedstawimy nasze subiektywne podsumowanie nowinek z tematyki kosmicznych maserów, m.in. zmienność emisji metanolu, megamasery, poznawanie struktury Drogi Mlecznej, powstawanie gwiazd. http://iaus336.oa-cagliari.inaf.it/
30 October 2017, 10:15, Institute of Physics, Center of Quantum Optics, Toruń
Special Astrophysics Seminar
“The power of astrochemistry: from atoms to molecules to life”
Dr Dmitry Semenov (Max Planck Institute for Astronomy w Heidelbergu)
Chemical transformation of the atomic to molecular matter in space and the origin of life in the Universe, along with formation and characterization of exoplanets and their habitability are among the hottest topics in astronomy. To fully address these topics, consolidated efforts in observational, theoretical, and laboratory studies are needed. Astrochemistry, a relatively new interdisciplinary science that brings together astrophysics and chemistry at extreme conditions, stays at forefront of such investigations.
In my presentation I will be talking about power of astrochemistry, namely:
1) how physical conditions and chemistry in various cosmic objects can be probed via molecular lines;
2) how atoms can be transformed into molecules in space and turned into key prebiotic ingredients;
3) how key ingredients for life could have been delivered on early Earth and gave rise to first life.
Furthermore, I will present my ideas how I would organize an astrochemistry group based on the Dioscuri Center of Excellence in Astrophysics at the Toruń University and how it will be integrated into the current university research.
Seminarium dr Semenova zaplanowana w Instytucie Fizyki odbędzie się zamiast Seminarium Ogólnego w Piwnicach. Oprócz seminarium zaplanowany został specjalny wykład dla studentów astronomii pt. “Stellar nucleosynthesis and the origin of elements in the Universe” w CA w poniedziałek 30.10 o godz 13.00 oraz spotkanie z pracownikami i studentami Centrum Astronomii.
25 October 2017, 10:15, Institute of Physics, Center of Quantum Optics
Special Astrophysics Seminar
“Using astrochemistry to unravel star and planet formation”
Dr Lars E. Kristensen (Centre for Star and Planet Formation, Niels Bohr Institute and Natural History Museum of Denmark)
The space between stars is not empty, but filled with large clouds of gas and dust. It is in these clouds that stars and planets, like our own Solar System, currently form. The gas consists of simple molecules with two and three atoms, like water, but also larger complex organic, even pre-biotic species such as sugars, alcohols, and maybe even amino acids. These molecules tell a story of the physical conditions during star and planet formation, once their chemistry is properly understood. In this seminar I will discuss the advances we are currently making in astrochemistry, the science bridging astrophysics and chemistry, and how we use that knowledge to infer how stars and planets form. I will do so by linking results from past (Herschel Space Observatory), present (SubMillimeter Array, Atacama Large Millimeter/submillimeter Array), and future (James Webb Space Telescope) observing facilities, thereby paving the way for addressing the big questions of how complex molecules form, and how they may be delivered to young planets.
23 October 2017
“Geometria wiązki radiowej pulsarów, czyli o odkryciach już poczynionych przez innych”
dr hab. Jarosław Dyks (Centrum Astronomiczne im. M. Kopernika, Toruń)
Problem kształtu radiowiązki pulsarowej to typowa w świecie nauki zagadka, gdy znamy tylko niektóre przekroje jakiegoś obiektu, a musimy z nich odtworzyć jak wygląda trójwymiarowy obiekt. Przekrojów takich, czyli profili pulsów, znamy obecnie kilka tysięcy. Historia odgadywania jaka fizyka za nimi stoi, pełna jest interesujących wzlotów i upadków, rewitalizacji zakurzonych idei i odkrywania już odkrytego. Problem jest tym bardziej nieznośny, że niektóre profile mają zdumiewająco symetryczny kształt, sugerujący proste rozwiązanie. Jaki jest kształt wiązki radiowej pulsarów?
16 October 2017
“Widma radiowe mgławic planetarnych”
dr Marcin Hajduk (Uniwersytet Warmińsko-Mazurski w Olsztynie)
Promieniowanie radiowe mgławic planetarnych pochodzi z termicznej emisji plazmy. Widma radiowe mgławic planetarnych są źródłem informacji o ich strukturze i parametrach fizycznych. W literaturze istnieje kilka konkurujących modeli emisji radiowej mgławic planetarnych. Przedstawię wyniki analizy obserwacji radiowych 54 mgławic w obserwowanych w szerokim zakresie częstości. Przedstawię także perspektywę dalszych badań mgławic za pomocą interferometru LOFAR.
9 October 2017, 11:00
public defence of PhD thesis
mgr Beata Deka-Szymankiewicz
PhD thesis title: Parametry podolbrzymów i karłów w próbce PTPS.
18 September 2017, godz. 11:00
“Radio Astronomy in Yamaguchi University”
prof. Kenta FUJISAWA (Yamaguchi University)
Wykład o obserwacjach emisji maserowej metanolu 32m radioteleskopem w Yamaguchi.