Study of the Balmer Decrements for Galactic Classical Be Stars Using the Himalayan Chandra Telescope of India
Gourav Banerjee,
Department of Physics and Electronics, CHRIST (Deemed to be University), Hosur Main Road, Bangalore, India. Corresponding author: gourav.banerjee@res.christuniversity.in
Blesson Mathew,
Department of Physics and Electronics, CHRIST (Deemed to be University), Hosur Main Road, Bangalore, India
Suman Bhattacharyya,
Department of Physics and Electronics, CHRIST (Deemed to be University), Hosur Main Road, Bangalore, India
Ashish Devaraj,
Department of Physics and Electronics, CHRIST (Deemed to be University), Hosur Main Road, Bangalore, India
Sreeja Kartha,
Department of Physics and Electronics, CHRIST (Deemed to be University), Hosur Main Road, Bangalore, India
Santosh Joshi,
Aryabhatta Research Institute of Observational Sciences, Nanital, India
Abstract
In a recent study, Banerjee et al. (2021) produced an atlas of all major emission lines found in a large sample of 115 Galactic field Be stars using the 2-m Himalayan Chandra Telescope (HCT) facility located at Ladakh, India. This paper presents our further exploration of these stars to estimate the electron density in their discs. Our study using Balmer decrement values indicate that their discs are generally optically thick in nature with electron density (ne) in their circumstellar envelopes (CEs) being in excess of 1013 cm-3 for around 65% of the stars. For another 19% stars, the average ne in their discs probably range between 1012 cm-3 and 1013 cm-3. We noticed that the nature of the Hα and Hβ line profiles might not influence the observed Balmer decrement values (i.e. D34 and D54) of the sample of stars. Interestingly, we also found that around 50% of the Be stars displaying D34 greater than 2.7 are of earlier spectral types, i.e. within B0 -B3.
Keywords : Be star, spectroscopy, emission lines, Balmer decrement, variability
Pour citer cet article
Gourav Banerjee, Blesson Mathew, Suman Bhattacharyya, Ashish Devaraj, Sreeja Kartha & Santosh Joshi, «Study of the Balmer Decrements for Galactic Classical Be Stars Using the Himalayan Chandra Telescope of India», Bulletin de la Société Royale des Sciences de Liège [En ligne], Volume 93 - Année 2024, No 2 - Proceeedings of the 3rd BINA Workshop on the Scientific Potential of the Indo-Belgian Cooperation, 504-513 URL : http://popups.ulg.be/0037-9565/index.php?id=11771.
