OPTICAL SPECTROSCOPY OF CLASSICAL Be STARS IN THE GALAXY. Study of stellar gaseous discs

      Аннотация: Spectroscopic study of classical Be (Be) stars is important to better understand their disc physics. Recently, Banerjee et al. (2021) produced an atlas of all major emission lines found in a large sample of over 100 field Be stars using the 2-m Himalayan Chandra Telescope facility of the Indian Institute of Astrophysics (IIA) located at Ladakh, India. This study revealed several important aspects of Be star discs, such as the importance of considering the extinction parameter (AV) for studying Be star properties, their discs are generally optically thick in nature, probable existence of non-isothermal discs in some such stars which might be responsible for the production of Ca II triplet emission lines, etc. In another separate study (Banerjee et al. 2022), we focused in understanding the disc transient nature of Be stars through continuous monitoring of their Hα line profile variations for 5 consecutive years using the 1-m telescope facility at the Vainu Bappu Observatory, Kavalur, India operated by IIA. Our work thus opens a broad scope to perform further dedicated studies of Be stars using larger samples to better understand their disc properties.

Ключевые слова: Be star, spectroscopy, emission lines, Balmer decrement, variability