A&A 601, A58 (2017) Astronomy DOI: 10.1051/0004-6361/201730437 & c ESO 2017 Astrophysics Spectroscopic twin to the hypervelocity sdO star US 708 and three fast sdB stars from the Hyper-MUCHFUSS project E. Ziegerer1, U. Heber1, S. Geier1; 2; 3; 4, A. Irrgang1, T. Kupfer5, F. Fürst5; 6, and J. Schaffenroth1 1 Dr. Karl Remeis-Observatory & ECAP, Astronomical Institute, Friedrich-Alexander University Erlangen-Nürnberg, Sternwartstr. 7, 96049 Bamberg, Germany e-mail:
[email protected] 2 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany 3 Department of Physics, University of Warwick, Coventry CV4 AL, UK 4 Institute for Astronomy and Astrophysics, Kepler Center for Astro and Particle Physics, Eberhard Karls University, Sand 1, 72076 Tübingen, Germany 5 Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Passadena, CA 91125, USA 6 European Space Astronomy Centre (ESA/ESAC), Operations Department, 28692 Villanueva de la Cañada (Madrid), Spain Received 13 January 2017 / Accepted 26 March 2017 ABSTRACT Important tracers for the dark matter halo of the Galaxy are hypervelocity stars (HVSs), which are faster than the local escape velocity of the Galaxy and their slower counterparts, the high-velocity stars in the Galactic halo. Such HVSs are believed to be ejected from the Galactic centre (GC) through tidal disruption of a binary by the super-massive black hole (Hills mechanism). The Hyper-MUCHFUSS survey aims at finding high-velocity potentially unbound hot subdwarf stars. We present the spectroscopic and kinematical analyses of a He-sdO as well as three candidates among the sdB stars using optical Keck/ESI and VLT (X-shooter, FORS) spectroscopy.