Classification of B-type hot subdwarf candidates
Fatima Waqar, Veronika Schaffenroth, Matti Dorsch
 Institut fu ̈r Physik und Astronomie, Universit ̈at Potsdam,  Thu ̈ringer Landessternwarte Tautenburg, Karl Schwarzschild Observatorium
B-type hot subdwarfs are subluminous objects that lie close to the extreme horizontal branch in the Hertzsprung Russell diagram. As helium burning stars with radii of only 0.2 R⊙ and masses of 0.5 M⊙, these hot stars must have lost their extensive hydrogen envelopes at the tip of the RGB. This can only be explained by binary evolution: indeed at least one third of the B-type hot subdwarfs are estimated to be in close binaries. The binary companion can be a white dwarf, M-type star or a substellar object. The binary companion causes variability in their light curves, from the reflection effect to tidal deformation, eclipses, and pulsation. The main goal of this project is to improve the selection of the hot subdwarf candidate catalogue by classifying the targets and placing them in the Gaia colour magnitude diagram. Lightcurves of more than 3000 targets showing light variations were selected and obtained from Transiting Exoplanet Survey Satellite (TESS). Lightcurves were downloaded and processed to find the period and then phase folded for classification. Further analysis with the spectral energy distribution will provide angular diameter on the sky and effective temperature. Combined with parallax measured by Gaia we will derive the stellar radii and the absolute luminosities. Here we will share the status of the project and present the phase folded lightcurves of our targets from TESS.