Blue Straggler Stars of NGC 7789 and NGC 2506 Using AstroSat/UVIT
Kaushar Vaidya,
Department of Physics, Birla Institute of Technology and Science, Pilani, 333031, India. Corresponding author: kaushar@pilani.bits-pilani.ac.in
Anju Panthi,
Department of Physics, Birla Institute of Technology and Science, Pilani, 333031, India
Vikrant Jadhav,
Helmholtz-Institut fur Strahlen-und Kernphysik, Universitat Bonn, Nussallee 14-16, D-53115 Bonn, Germany
Khushboo Kunwar Rao,
Department of Physics, Birla Institute of Technology and Science, Pilani, 333031, India
Sindhu Pandey,
Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital, 263001, India
Annapurni Subramaniam,
Indian Institute of Astrophysics, Sarjapur Road, Koramangala, Bangalore, 560034, India
Manan Agarwal,
Department of Physics, Birla Institute of Technology and Science, Pilani, 333031, India and Anton Pannekoek Institute for Astronomy, University of Amsterdam, P.O. Box 94249, 1090GE Amsterdam, Noord Holland, Netherlands
Abstract
Blue straggler stars are intriguing objects that seem to defy the standard theory of single-star evolution. They manage to elongate their main-sequence lifetimes by acquiring mass either in a direct stellar collision or through mass transfer in a binary or in mergers. We study the candidate blue straggler stars in two intermediate-age open clusters NGC 7789 and NGC 2506 using the far-UV and near-UV observations from the UV imaging telescope of AstroSat in combination with other multi-wavelength data. Around 45% of blue straggler star candidates show an excess in the UV wavelengths and are fitted with two-component spectral energy distributions. We detect most of these blue straggler stars to contain a low-mass or extremely low-mass white dwarf as a hot companion, whereas some yellow straggler stars and red clump stars with white dwarfs of normal mass or high mass as a companion. Based on our analysis, we infer that around 36% of blue straggler stars have likely formed via mass transfer by the Case-A/Case-B mechanism in these two clusters.
Keywords : Open clusters, Stars, Exotic stars, Blue straggler stars, Yellow straggler stars
To cite this article
Kaushar Vaidya, Anju Panthi, Vikrant Jadhav, Khushboo Kunwar Rao, Sindhu Pandey, Annapurni Subramaniam & Manan Agarwal, «Blue Straggler Stars of NGC 7789 and NGC 2506 Using AstroSat/UVIT», 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, 250-261 URL : http://popups.ulg.be/0037-9565/index.php?id=11667.
