1 research outputs found
Field blue straggler stars: Discovery of white dwarf companions to blue metal-poor stars using UVIT/AstroSat
Blue metal-poor (BMP) stars are the main-sequence stars that appear bluer and
more luminous than normal turn-off stars of metal-poor globular clusters. They
are believed to be either field blue straggler stars (FBSS) formed via
post-mass transfer mechanism or accreted from dwarf satellite galaxies of the
Milky Way. A significant fraction of BMP stars are discovered to be potential
binaries. We observed 27 BMP stars using UVIT/\textit{AstroSat} in two FUV
filters, F148W and F169M. We report the discovery of white dwarf (WD)
companions of 12 BMP stars for the first time. The WD companions have estimated
temperatures T 10500 18250 K, and masses 0.17 M
0.8 M. Based on [Fe/H] and space velocity, we group the 12 BMP/FBSS
stars as the thick disk (5) and halo (5), whereas two stars appear to be
in-between. All the 5 thick disk BMP/FBSS have extremely low-mass (M 0.2
M) WDs as companions, whereas the 5 halo BMP/FBSS have low (0.2
M M 0.4 M), normal (0.4 M M
0.6M), and high mass (M 0.6 M) WD companions. Our
analysis suggests that at least 44 of BMP stars are FBSS, and these
stars hold the key to understand the details of mass transfer, binary
properties, and chemical enrichment among the FBSS