Abstract Details

Name: Nevil Shah
Affiliation: IISER Mohali
Conference ID: ASI2020_181
Title : A multi-wavelength view of the open cluster NGC 2527: Discovery of active stars
Authors and Co-Authors : Nevil Shah, K. P. Singh, Annapurni Subramaniam
Abstract Type : Poster
Abstract Category : Stars, ISM and Galaxy
Abstract : We present a comprehensive study of an open cluster NGC 2527 based on XMM-Newton (X-ray), Swift UVOT (UV/optical), and Gaia (optical) data carried out by us. Our study has revealed the presence of several active stars in this cluster for the first time. We fitted the Gaia optical and UV colour-magnitude diagrams (CMDs) with PARSEC isochrones to search for peculiar stars that do not follow the standard evolutionary models. We have detected 5 sub-subgiants and 5 bandgap stars that deviate from the best fitting isochrones. We searched for optical counterparts of sources detected in XMM and Swift UVOT observations and found that of the 358 cluster members, 12 are X-ray and 54 are UV emitting sources. We have estimated the temperature, mass, radius, and luminosity of these sources by fitting the observed broad-band Spectral Energy Distributions with Kurucz model spectra. Among the X-ray emitting members, we find that 5 are potential RS CVn type binaries, 2 are potential FK Comae type of red giant (RG) stars, and 5 are main-sequence (MS) stars with high coronal activity. Members with strong UV emission comprise of 1 RG star and several MS stars with UV excess suggestive of chromospheric activity. We confirm that X-ray luminosity of both the RS CVn and contact binaries increases with age, suggesting more active binaries are present in the older clusters as compared to the younger clusters. Our study suggests that the presence of W Uma and FK Comae type of stars in younger clusters may not be uncommon.