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Low-mass stellar and substellar companions to sdB stars
S. Geier, L. Classen, P. Bruenner +9
It has been suggested that besides stellar companions, substellar objects in close orbits may be able to trigger mass loss in a common envelope phase and form hot subdwarfs. In an…
The MUCHFUSS project - Searching for the most massive companions to hot subdwarf stars in close binaries and finding the least massive ones
S. Geier, V. Schaffenroth, H. Hirsch +12
The project Massive Unseen Companions to Hot Faint Underluminous Stars from SDSS (MUCHFUSS) aims at finding hot subdwarf stars with massive compact companions (massive white dwarfs…
The fast rotating, low gravity subdwarf B star EC 22081-1916 - Remnant of a common envelope merger event
S. Geier, L. Classen, U. Heber
Hot subdwarf B stars (sdBs) are evolved core helium-burning stars with very thin hydrogen envelopes. In order to form an sdB, the progenitor has to lose almost all of its hydrogen…
Radial Velocity Survey of Low-Mass Companions to sdB Stars
L. Classen, S. Geier, U. Heber +1
The origin of subdwarf B (sdB) stars is not fully understood yet since it requires high mass loss at the red giant stage. SdBs in close binary systems are formed via common envelop…
Substellar companions and the formation of hot subdwarf stars
S. Geier, U. Heber, A. Tillich +12
We give a brief review over the observational evidence for close substellar companions to hot subdwarf stars. The formation of these core helium-burning objects requires huge mass…
Radial Velocity search for substellar companions to sdB stars
S. J. O'Toole, U. Heber, S. Geier +2
After the discovery of a substellar companion to the hot subdwarf HD 149382, we have started a radial velocity search for similar objects around other bright sdB stars using the An…