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Paper: A Radial Velocity Survey of Hot Subdwarfs with Main Sequence Companions using the Hobby–Eberly Telescope
Volume: 481, 6th Meeting on Hot Subdwarf Stars and Related Objects
Page: 311
Authors: Wade, R.; Barlow, B.; Liss, S.; Stark, M.
Abstract: Binary population synthesis models are generally successful at reproducing the observed periods of hot subdwarf binaries with M dwarf or white dwarf companions; the story for sdB+F/G/K binaries, however, is still being written. Relatively few observational constraints have been published for these composite-spectra systems. We have been monitoring the radial velocities (RVs) of 15 hot subdwarf binaries with late F – K dwarf companions since 2005 using the Medium and High Resolution Spectrographs on the Hobby-Eberly Telescope. Here we present RV measurements and orbital parameter estimates for selected systems in our sample. We also present an up-to-date period histogram for all known hot subdwarf binaries, including both short- and long-period systems. Our initial results suggest that those with late F – K main sequence companions have orbital periods on the order of 1.5 to 3 years. Several of the long-period binaries show strong evidence for non-circular orbits, challenging the conventional Roche Lobe overflow formation channel for hot subdwarfs.
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