Title: When massive stars spinning too fast: Be phenomena in the mid-infrared
Speaker: Mingjie Jian
Affiliation: Stockholm University
Time: Thursday 17th October 2024, 14:00 to 15:00
Location: 10134 Å (Polhemsalen)
Abstract: Massive stars are one of the important test labs on how the material behaves in extreme physical situations. As fast rotators, the material in their equator may be ejected from the star’s surface, forming a so-called decretion disk. Current models show that when a star develops a decretion disk, it would become brighter and redder in the infrared. Such behavior shed light on detecting Be stars, or moreover, the transition process between B and Be stars in IR. We found that 916 Be stars (736 of which are newly discovered) developed/lost decretion disks in the past 13 year using the light curve from the WISE satellite. Further investigation using Gaia catalog as input shows that the number of such stars is expected to be around 3000, an order larger than those found in the previous studies. Combining the WISE and optical photometry, as well as the epoch spectroscopic observation (LAMOST, 4MOST, etc) would provide important constraints on the mechanism of decretion disk formation.