分类： 天文学 >> 天文学 提交时间： 2023-02-19
Luqian Wang
Douglas R. Gies
Geraldine J. Peters
Ylva Götberg
S. Drew Chojnowski
Kathryn V. Lester
Steve B. Howell
摘要： The B-emission line stars are rapid rotators that were probably spun up by mass and angular momentum accretion through mass transfer in an interacting binary. Mass transfer will strip the donor star of its envelope to create a small and hot subdwarf remnant. Here we report on Hubble Space Telescope/STIS far-ultraviolet spectroscopy of a sample of Be stars that reveals the presence of the hot sdO companion through the calculation of cross-correlation functions of the observed and model spectra. We clearly detect the spectral signature of the sdO star in 10 of the 13 stars in the sample, and the spectral signals indicate that the sdO stars are hot, relatively faint, and slowly rotating as predicted by models. A comparison of their temperatures and radii with evolutionary tracks indicates that the sdO stars occupy the relatively long-lived, He-core burning stage. Only one of the ten detections was a known binary prior to this investigation, which emphasizes the difficulty of finding such Be+sdO binaries through optical spectroscopy. However, these results and others indicate that many Be stars probably host hot subdwarf companions.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Sam Geen
Poojan Agrawal
Paul A. Crowther
B. W. Keller
Alex de Koter
Zsolt Keszthelyi
Freeke van de Voort
Ahmad A. Ali
Frank Backs
Lars Bonne
Vittoria Brugaletta
Annelotte Derkink
Sylvia Ekström
Yvonne A. Fichtner
Luca Grassitelli
Ylva Götberg
Erin R. Higgins
Eva Laplace
Kong You Liow
Marta Lorenzo
摘要： Stars strongly impact their environment, and shape structures on all scales throughout the universe, in a process known as ``feedback''. Due to the complexity of both stellar evolution and the physics of larger astrophysical structures, there remain many unanswered questions about how feedback operates, and what we can learn about stars by studying their imprint on the wider universe. In this white paper, we summarize discussions from the Lorentz Center meeting `Bringing Stellar Evolution and Feedback Together' in April 2022, and identify key areas where further dialogue can bring about radical changes in how we view the relationship between stars and the universe they live in.
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