Abstract

Invited Talk - Plenary

A new class of stripped star binaries with compact companions

Stephan Geier
Institute for Physics and Astronomy, University of Potsdam

Due to interactions with their companions in the red giant stage, low-mass stars can be stripped leading to the formation of helium stars of hot subdwarf (sdO/B) type. The majority of those post mass transfer binaries has compact white dwarf companions in close orbits with periods of hours to days. Based on Gaia astrometry we discovered a yet unknown class with much longer periods of hundreds of days. Those objects challenge our understanding of binary evolution and some might be progenitors of thermonuclear supernovae or ultracompact X-ray binaries.