The catalogue of radial velocity variable hot subluminous stars from the MUCHFUSS project^⋆

¹ European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
e-mail: sgeier@eso.org
² Dr. Karl Remeis-Observatory & ECAP, Astronomical Institute, Friedrich-Alexander University Erlangen-Nuremberg, Sternwartstr. 7, 96049 Bamberg, Germany
³ Department of Astrophysics/IMAPP, Radboud University Nijmegen, PO Box 9010, 6500 GL Nijmegen, The Netherlands
⁴ Institute for Astro- and Particle Physics, University of Innsbruck, Technikerstr. 25/8, 6020 Innsbruck, Austria
⁵ Department of Physics, High Point University, 833 Montlieu Avenue, High Point, NC 27268, USA
⁶ Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Heverlee, Belgium
⁷ Australian Astronomical Observatory, PO Box 915, North Ryde NSW 1670, Australia
⁸ Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK
⁹ Department of Physics, University of Warwick, Conventry CV4 7AL, UK
¹⁰ Centre of Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK

Received: 15 January 2015
Accepted: 17 February 2015

Abstract

The project Massive Unseen Companions to Hot Faint Underluminous Stars from SDSS (MUCHFUSS) aims to find sdBs with compact companions such as massive white dwarfs, neutron stars, or black holes. Here we provide classifications, atmospheric parameters, and a complete radial velocity (RV) catalogue containing 1914 single measurements for a sample of 177 hot subluminous stars discovered based on SDSS DR7; 110 stars show significant RV variability, while 67 qualify as candidates. We constrain the fraction of close massive compact companions of hydrogen-rich hot subdwarfs in our sample to be smaller than ~1.3%, which is already close to the theoretical predictions. However, the sample might still contain such binaries with longer periods exceeding ~8 d. We detect a mismatch between the ΔRV_max-distribution of the sdB and the more evolved sdOB and sdO stars, which challenges our understanding of their evolutionary connection. Furthermore, irregular RV variations of unknown origin with amplitudes of up to ~180 km s^-1 on timescales of years, days, and even hours have been detected in some He-sdO stars. They might be connected to irregular photometric variations in some cases.