The MUCHFUSS photometric campaign

Abstract

Hot subdwarfs (sdO/Bs) are the helium-burning cores of red giants, which lost almost all of their hydrogen envelopes. This mass loss is often triggered by common envelope interactions with close stellar or even substellar companions. Cool companions like late-type stars or brown dwarfs are detectable via characteristic light curve variations like reflection effects and often also eclipses. To search for such objects we obtained multi-band light curves of 26 close sdO/B binary candidates from the MUCHFUSS project with the BUSCA instrument. We discovered a new eclipsing reflection effect system ($P=0.168938$~d) with a low-mass M dwarf companion ($0.116M_{\odot }$). Three more reflection effect binaries found in the course of the campaign were already published, two of them are eclipsing systems, in one system only showing the reflection effect but no eclipses the sdB primary is found to be pulsating. Amongst the targets without reflection effect a new long-period sdB pulsator was discovered and irregular light variations were found in two sdO stars. The found light variations allowed us to constrain the fraction of reflection effect binaries and the substellar companion fraction around sdB stars. The minimum fraction of reflection effect systems amongst the close sdB binaries might be greater than 15\% and the fraction of close substellar companions in sdB binaries might be as high as $8.0\%$. This would result in a close substellar companion fraction to sdB stars of about 3\%. This fraction is much higher than the fraction of brown dwarfs around possible progenitor systems, which are solar-type stars with substellar companions around 1 AU, as well as close binary white dwarfs with brown dwarf companions. This might be a hint that common envelope interactions with substellar objects are preferentially followed by a hot subdwarf phase.

arXiv commentaccepted for A&A

References in corpus (43)

• Stellar Multiplicity
• Common Envelope Evolution: Where we stand and how we can move forward
• The Occurrence and Architecture of Exoplanetary Systems
• The Origin of Subdwarf B Star (I): the Formation Channels
• The origin of sdB stars (II)
• Hot subluminous stars
• Spectroscopic Analysis of DA White Dwarfs: Stark Broadening of Hydrogen Lines Including Non-Ideal Effects
• The binary fraction of extreme horizontal branch stars
• Search for brown-dwarf companions of stars
• Survival of a brown dwarf after engulfment by a red giant star
• A selection of hot subluminous stars in the GALEX survey II. Subdwarf atmospheric parameters
• First Kepler results on compact pulsators I. Survey target selection and the first pulsators
• Hot subdwarfs from the ESO Supernova Ia Progenitor Survey - I. Atmospheric parameters and cool companions of sdB stars
• Hot subdwarf binaries from the MUCHFUSS project - Analysis of 12 new systems and a study of the short-period binary population
• A progenitor binary and an ejected mass donor remnant of faint type Ia supernovae
• The MUCHFUSS project - Searching for hot subdwarf binaries with massive unseen companions: Survey, target selection and atmospheric parameters
• A Possible Brown Dwarf Companion to the White Dwarf GD1400
• HS 0705+6700: a new eclipsing sdB binary
• 2M1938+4603: A rich, multimode pulsating sdB star with an eclipsing dM companion observed with Kepler
• The binary properties of the pulsating subdwarf B eclipsing binary PG 1336-018 (NY Vir)
• The quest for companions to post-common envelope binaries: III. A reexamination of HW Virginis
• A survey for pulsating subdwarf B stars with the Nordic Optical Telescope
• A simple model of the reflection effect for the interacting binaries and extrasolar planets
• Modeling the System Parameters of 2M1533+3759: A New Longer-Period Low-Mass Eclipsing sdB+dM Binary
• New binaries among UV-selected, hot subdwarf stars and population properties
• The catalogue of radial velocity variable hot subluminous stars from the MUCHFUSS project
• Binaries discovered by the MUCHFUSS project SDSS J08205+0008 - An eclipsing subdwarf B binary with brown dwarf companion
• NLTT5306: The shortest Period Detached White Dwarf + Brown Dwarf Binary
• Two white dwarfs in ultrashort binaries with detached, eclipsing, likely substellar companions detected by K2
• The substellar companion in the eclipsing white dwarf binary SDSS J141126.20+200911.1
• Binaries discovered by the MUCHFUSS project: SDSS J162256.66$+$473051.1 - An eclipsing subdwarf B binary with a brown dwarf companion
• Third generation stellar models for asteroseismology of hot B subdwarf stars. A test of accuracy with the pulsating eclipsing binary PG 1336--018
• WD0837+185:the formation and evolution of an extreme mass ratio white dwarf-brown dwarf binary in Praesepe
• Massive unseen companions to hot faint underluminous stars from SDSS (MUCHFUSS) - Analysis of seven close subdwarf B binaries
• A photometric and spectroscopic study of NSVS 14256825: the second sdOB+dM eclipsing binary
• EC 10246-2707: a new eclipsing sdB + M dwarf binary
• A new bright eclipsing hot subdwarf binary from the ASAS and SuperWASP surveys
• An eclipsing post common-envelope system consisting of a pulsating hot subdwarf B star and a brown dwarf companion
• Orbital solutions of eight close sdB binaries and constraints on the nature of the unseen companions
• An extremely fast halo hot subdwarf star in a wide binary system
• Looking at the bright side - The story of AA Dor as revealed by its cool companion
• A new sdO+dM binary with extreme eclipses and reflection effect
• A new HW Vir binary from the Palomar Transient Factory: PTF1 J072455.75+125300.3 - An eclipsing subdwarf B binary with a M-star companion

Cited by in corpus (14)

• Hot subdwarfs in close binaries observed from space I: orbital, atmospheric, and absolute parameters and the nature of their companions
• The EREBOS project -- Investigating the effect of substellar and low-mass stellar companions on late stellar evolution
• Formation of sdB-stars via common envelope ejection by substellar companions
• A quantitative in-depth analysis of the prototype sdB+BD system SDSS J08205+0008 revisited in the Gaia era
• Radial velocity variability and evolution of hot subdwarf stars
• A transit survey to search for planets around hot subdwarfs: I. methods and performance tests on light curves from Kepler, K2, TESS, and CHEOPS
• Hot subdwarfs in close binaries observed from space II: Analysis of the light curves
• Hot Subdwarf All Southern Sky Fast Transit Survey with the Evryscope
• Possible substellar companions in dwarf eclipsing binaries: SDSS J143547.87+373338.5, NSVS 7826147, and NSVS 14256825
• Minimum Orbital Period of Pre-Cataclysmic Variables
• Discovery of new TESS pulsating hot subdwarfs
• Advanced Classification of Hot Subdwarf Binaries Using Artificial Intelligence Techniques and Gaia DR3 data
• Identifying and characterising the population of hot sub-luminous stars with multi-colour MeerLICHT data
• ZTFJ0038+2030: a long period eclipsing white dwarf and a substellar companion