Study of transient nature of classical Be stars using multi-epoch optical spectroscopy
subject: Bestars: circumstellar matter; Techniques: spectroscopicstars: emission-line
description: Variability is a commonly observed property of classical Be stars (CBe) stars. In extreme cases, complete disappearance of the H? emission line occurs, indicating a disc-less state in CBe stars. The disc-loss and reappearing phases can be identified by studying the H? line profiles of CBe stars on a regular basis. In this paper, we present the study of a set of selected nine bright CBe stars, in the wavelength range of 62006700 to better understand their disc transient nature through continuous monitoring of their H? line profile variations for five consecutive years (20152019). Based on our observations, we suggest that four of the program stars (HD 4180, HD 142926, HD 164447 and HD 171780) are possibly undergoing disc-loss episodes, whereas one other star (HD 23302) might be passing through disc formation phase. The remaining four stars (HD 237056, HD 33357, HD 38708 and HD 60855) have shown signs of hosting a stable disc in recent epochs. Through visual inspection of the overall variation observed in the H? EW for these stars, we classified them into groups of growing, stable and dissipating discs, respectively. Moreover, our comparative analysis using the BeSS database points out that the star HD 60855 has passed through a disc-less episode in 2008, with its disc formation happening probably over a timescale of only two months, between January and March 2008. 2022, Indian Academy of Sciences.
creator: Banerjee G.; Mathew B.; Paul K.T.; Subramaniam A.; Balan A.; Bhattacharyya S.; Anusha R.; Moosa D.; Dheeraj C.S.; Charly A.; Raghu M.
source: Journal of Astrophysics and Astronomy, Vol-43, No. 2
publisher: Springer
date: 2022-01-01
rights: All Open Access; Green Open Access
relation: ISSN: 2506335
format: Online
language: English
type: Article
coverage: Banerjee G., Department of Physics and Electronics, CHRIST (Deemed to be University), Hosur Main Road, Bengaluru, 560029, India; Mathew B., Department of Physics and Electronics, CHRIST (Deemed to be University), Hosur Main Road, Bengaluru, 560029, India; Paul K.T., Department of Physics and Electronics, CHRIST (Deemed to be University), Hosur Main Road, Bengaluru, 560029, India; Subramaniam A., Indian Institute of Astrophysics, Koramangala, Bengaluru, 560034, India; Balan A., Department of Physics and Electronics, CHRIST (Deemed to be University), Hosur Main Road, Bengaluru, 560029, India; Bhattacharyya S., Department of Physics and Electronics, CHRIST (Deemed to be University), Hosur Main Road, Bengaluru, 560029, India; Anusha R., Department of Physics and Astronomy, University of Western Ontario, London, N6A 3K7, ON, Canada; Moosa D., Department of Physics and Electronics, CHRIST (Deemed to be University), Hosur Main Road, Bengaluru, 560029, India; Dheeraj C.S., Department of Physics and Electronics, CHRIST (Deemed to be University), Hosur Main Road, Bengaluru, 560029, India; Charly A., Department of Physics and Electronics, CHRIST (Deemed to be University), Hosur Main Road, Bengaluru, 560029, India; Raghu M., Department of Physics and Electronics, CHRIST (Deemed to be University), Hosur Main Road, Bengaluru, 560029, India