The population of close binary hot subdwarfs studied with light curves from space telescopes

• Applicant: Professor Dr. Stephan Geier
• Subject Area: Astrophysics and Astronomy
• Term: from 2018 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 400079267

Hot subdwarf stars (sdO/Bs) are the stripped cores of red-giant stars and are most likely formed via binary interactions. Close-binary subdwarfs show characteristic signatures in their light curves caused by eclipses, the reflection effect, the ellipsoidal deformation of the sdB primary or the very shallow relativistic Doppler boosting. However, ground-based light curve surveys are only sensitive to variations at the percent level and do not allow us to study the full population of close hot subdwarf binaries. Here we apply for a PostDoc postion to perform an analysis of all the 3200 sdO/B light curves obtained from space by the TESS mission as well as the 40000 light curves obtained by the Gaia mission. The classification of binary signatures will allow us to put meaningful constraints on the close binary properties of sdO/B stars. Furthermore, we will combine an analysis of the TESS light curves with spectroscopic parameters from literature for about 30 eclipsing and ellipsoidal variable sdB+WD binaries to determine their fundamental parameters.

• DFG Programme: Research Grants