1 research outputs found
The EREBOS project -- Investigating the effect of substellar and low-mass stellar companions on late stellar evolution
Eclipsing post-common envelope binaries are highly important for resolving
the poorly understood, very short-lived common envelope phase. Most hot
subdwarfs (sdO/Bs) are the bare He-burning cores of red giants which have lost
almost all of their hydrogen envelopes. This mass loss is often triggered by
common envelope interactions with close stellar or even sub-stellar companions.
In the recently published catalog of eclipsing binaries in the Galactic Bulge
and in the ATLAS survey, we discovered 161 new eclipsing systems showing a
reflection effect by visual inspection of the light curves and using a
machine-learning algorithm. The EREBOS (Eclipsing Reflection Effect Binaries
from Optical Surveys) project aims at analyzing all newly discovered eclipsing
binaries with reflection effect based on a spectroscopic and photometric follow
up. To constrain the nature of the primary we derived the absolute magnitude
and the reduced proper motion of all our targets with the help of the
parallaxes and proper motions measured by the Gaia mission and compared those
to the Gaia white dwarf catalogue. For a sub-set of our targets with observed
spectra the nature could be derived by measuring the atmospheric parameter of
the primary confirming that less than 10\% of our systems are not sdO/Bs with
cool companions but white dwarfs or central stars of planetary nebula. This
large sample of eclipsing hot subdwarfs with cool companions allowed us to
derive a significant period distribution for hot subdwarfs with cool companions
for the first time showing that the period distribution is much broader than
previously thought and ideally suited to find the lowest mass companions to hot
subdwarf stars. In the future several new photometric surveys will be carried
out, which will increase the sample of this project even more giving the
potential to test many aspects of common envelope theory and binary evolution.Comment: accepted in A&A, 29 pages, 18 figure