Abstract Details

Name: Tirthendu Sinha
Affiliation: ARIES
Conference ID: ASI2021_498
Title : Pre-main sequence variables in young open clusters
Authors and Co-Authors : Tirthendu Sinha, Dr. Saurabh
Abstract Type : Oral
Abstract Category : Stars, ISM and Galaxy
Abstract : The evolution of pre-main sequence (PMS) star involves a set of complex physical processes such as evolution of circumstellar disks, accretion processes, bipolar jets and outflows, evolution of angular momentum etc. Study of variability and their causes in young open clusters can give us some clue about these process. Several mechanisms are known to induce these variability, for example irregular distribution of cool spots on stellar photosphere, variable hot spots, obscuration from dust, instability in disk, change in accretion rate etc. The evolution of disks and the accretion rates may play a prominent role in the non-periodic variability whereas due to the presence of cool and hot spots on the photosphere, rotation of the stars may produce periodic/quasi-periodic changes in their light curve. The period of the light curve of a rotating stars is direct indicator of it's rotation period and hence related to angular momentum. With the help of HR diagram we can constrain the physical parameters such as age and mass of PMS stars and it is easy to check the correlation of different physical parameters (period/amplitude, accretion rate etc. ) with age and mass. In our survey of PMS stars, many main sequence field stars are also detected as variables. Our study suggests that in a typical cluster we get as many as 30-40 periodic variables and 20-30 non periodic variables. Period of periodic variables ranges from few hours to 15-20 days while amplitude ranges from 0.05 mag to 2 mag. The amplitude of variables increases with IR excess where as rotation speed seems to slow down with IR excess. We will show the results of few clusters obtained in our study.