| Name: | Sidharth A V |
| Affiliation: | CHRIST (Deemed to be University), Bengaluru |
| Conference ID : | ASI2023_147 |
| Title : | Disk Variability of Classical Be stars using LAMOST medium-resolution spectra |
| Authors : | A V Sidharth, S Shriranjani, Blesson Mathew, S Bhattacharya , B Shridharan |
| Mode of Presentation: | Poster |
| Abstract Category : | Stars, ISM and Galaxy |
| Abstract : | Classical Be stars (CBe) are non-supergiant spectral type B stars indicated by Balmer emission lines that originate from their circumstellar disk. This circumstellar disk is formed from the ejection or decretion of mass from the star due to rotational speeds close to its critical velocity. The dynamical perturbations in the decretion disk can be observed as variability in Hα strength and profiles using multi-epoch medium-resolution spectra. CBe stars usually exhibit variability in the short-term (hours to months) as well as in long term (years to decades). Non-radial pulsation (NRP) explains significant line profile variability (LPV) on short-term and binarity effects are found to be an important source of intermediate-period disk variability. The extreme case of such variability is the appearance/disappearance of the Hα emission line, indicative of the formation of a disk or disk-less state in CBe stars. In this work, we use a catalogue of 1162 candidate Be stars identified from LAMOST Medium-Resolution (R ~ 7500) Spectra from LAMOST Data Release 7. We visually identified 25 variable Be stars, where 10 candidates show profile variability and 15 candidates show a change in Hα emission strength based on the multi-epoch data available for each star. Equivalent Widths and Full Widths at Half Maximum values were estimated for our sample of variable Be candidates. Light curve (V-mag) analyses were performed to calculate the period of variability for CBe systems. Results from these analyses will provide a reference for future investigations of the disc-formation in the vicinity of the CBe stars, as well as a better understanding of the LPV and the significance of binarity in decoding the “Be phenomenon”. |
