Welcome to the homepage of the IAU Working Group on Active B Stars and its Be Star Newsletter.

The Working Group on Active B Stars (WGABS) was formed to promote and stimulate research and international collaboration in the field of active B stars. The WGABS is open to all researchers interested in the field.

For an introduction to the features of this site and more details about the WGABS, please see "About this site", for further support or ideas how to improve the site please contact the online editors at This email address is being protected from spambots. You need JavaScript enabled to view it. or drop them in our suggestion box.

Please Note:  We will be gradually updating and refurbishing the web page, beginning with this home page. 

Upcoming: IAU Working Group on Active B Stars Talks

The WG has series of talks, normally held the third Wednesday of each month at 10:00 am Eastern Time (EST, 14:00 UT), by zoom.  The next talk is scheduled for Wednesday, June 15, 2022. Please note the time is ONE HOUR LATER than usual.

Seminar organizing committee: Carol Jones, Alex Carciofi, Dietrich Baade, Gregg Wade and Atsuo Okazaki. If have questions or suggestions for the s3eries, please contact the any of the committee members.

Speaker: Dr. Chen Wang, currently a postdoctoral researcher at Max-Planck Institute for Astrophysics (MPA)

Title: What can we learn from the multiple MS components detected in young star clusters?

Link: https://westernuniversity.zoom.us/j/98111632482


Recent high-precision Hubble Space Telescope (HST) photometry reveals that the main-sequences (MSs) of young star clusters in the color-magnitude diagram are split into several components. This challenges the traditional view of star clusters containing coeval stars born with identical initial conditions. We use detailed single and binary evolution models to investigate the origin of these multiple MS components. We find that binary mergers may produce slowly-rotating rejuvenated stars, which appear younger and bluer than other cluster members. In contrast, stable mass transfer creates near-critically-rotating stars, which coincides with the observed red Be sequence in young star clusters. Our results lead us to conclude that stars may either form by accretion, or through a binary merger, and that both paths lead to distinctly different spins, magnetic fields, and stellar mass distributions.



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