Contributed Talk - Splinter Stellar
Thursday, 24 September 2020, 17:35 (virtual room M)
A Catalogue of Blue Horizontal Branch Stars from Gaia DR2
Richard Culpan, Ingrid Pelisoli, Stephan Geier
University of Potsdam
Blue horizontal branch stars result from low-mass main-sequence stars (M < 2.3Msun) that have developed past the red giant phase. The age and brightness of these stars makes them excellent markers of galactic evolution and structure. Catalogues of blue horizontal branch stars have, to-date, relied on the existence of spectra. However, acquiring and analysing spectra is time intensive and is not conducive to generating large catalogues. We have used these spectrum-based catalogues to define the selection criteria for an all-sky catalogue of 68,000 blue horizontal branch stars relying on colour, parallax, apparent magnitude and proper motions from the Gaia DR2 data-set. The challenge of separating the main-sequence stars from the BHB candidates has been overcome using tangential velocity, and galactic latitude criteria as well as colour-colour plots using other large-scale surveys. The catalogue is considered to be statistically significant with a main-sequence contamination level of 1%. Having a clean catalogue of blue horizontal branch stars will support further studies aimed at understanding the evolution of galactic structure.