Institute of Astronomy

ContactPiwnice k. Torunia, 87-148 Łysomice
tel.: +48 56 611 30 10
fax: +48 56 611 30 09

General Seminar

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General Seminar takes place every Monday at 11.15 in Piwnice, radioastronomy seminar room.
Remote participation via the BigBlueButton (BBB).

11 December 2023

“Evolution of very massive binary stars and their observable counterparts.”

dr Koushik Sen (Institute of Astronomy, Nicolaus Copernicus University)

Our study focuses on very massive stars, which are commonly born in close binary systems. We analyse detailed binary evolution models (30…90 Msun) and identify four effects that challenge the current knowledge in binary evolution. All these effects are related to the proximity of the models to the Eddington limit. We find that most models undergo mass transfer during core hydrogen burning. During the following nuclear timescale evolution, many mass donors remain more massive than their companions (”reverse Algols”). For the highest masses, nuclear timescale mass transfer may be interrupted or absent completely due to an increased wind mass-loss rate from the donor that widens the binary. Due to the elevated luminosity-to-mass ratio, many core-hydrogen-burning donors may develop Wolf-Rayet-type winds at luminosities where single stars would not. We identify observed massive semi-detached binaries and hydrogen-rich Wolf-Rayet stars that are undergoing/have undergone the reverse Algol evolution channel. We argue that understanding very massive Algol systems is essential in predicting the advanced evolution of very massive binaries, including their potential to become observable gravitational wave sources.

18 December 2023

dr hab. Gracjan Maciejewski, prof. UMK (Institute of Astronomy, Nicolaus Copernicus University)


8 January 2024


15 January 2024

dr Marek Weżgowiec (Astronomical Observatory, Jagiellonian University)


22 January 2024

dr Dorottya Szécsi (Institute of Astronomy, Nicolaus Copernicus University)


29 January 2024

dr Rafael Luque (Department of Astronomy and Astrophysics, University of Chicago)


5 February 2024

dr hab. Roman Schreiber, prof. CBK (The Space Research Centre of the Polish Academy of Sciences)