Hot subdwarf binaries from the MUCHFUSS project Analysis of 12 new systems and a study of the short-period binary population

摘要: The project Massive Unseen Companions to Hot Faint Underluminous Stars from SDSS (MUCHFUSS) aims at finding hot subdwarf stars with massive compact companions like white dwarfs (M > 1.0 M⊙), neutron stars, or stellar-mass black holes. existence of such systems is predicted by binary evolution theory, and recent discoveries indicate that they exist in ou r Galaxy. We present orbital atmospheric parameters put constraints on the nature 12 close B star (sdB) binaries found course MUCHFUSS project. show periods between 0.14 7.4 days. In nine cases cannot be constrained unambiguously whereas three most likely have dwarf companions. find companion J083006.17+475150.3 a rare example low-mass helium-core dwarf. J095101.28+034757.0 shows an excess infrared probably originates third wide orbit, which makes this system second candidate hierarchical triple containing sdB star. J113241.58−063652.8 first helium deficient sdO confirmed companion. This study brings 142 number less than 30 days measured mass functions. analysis minimum distribution it bimodal. One peak around 0.1 M⊙ corresponds main sequence (dM) substellar other 0.4 derived masses for are significantly lower average single ca rbonoxygen dwarfs. Teff ‐ log g diagram sdB+dM companions, we signs components more rest sample. full sample was compared known population extremely as well short-period Both samples di fferent indicating either different selection effects evolutionary paths. identified 16 where dM will fill its Roche Lobe within Hubble time evolve into cataclysmic variable; two them brown donor Twelve merge time, having ratio stable AM CVn-type another potential supernova Ia progenitor systems. remaining eight form RCrB C/O depending structure