Radial Velocity Confirmation of a Binary Detected from Pulse Timings

Abstract

A periodic variation in the pulse timings of the pulsating hot subdwarf B star CS 1246 was recently discovered via the O-C diagram and suggests the presence of a binary companion with an orbital period of two weeks. Fits to this phase variation, when interpreted as orbital reflex motion, imply CS 1246 orbits a barycenter 11 light-seconds away with a velocity of 16.6 km/s. Using the Goodman spectrograph on the SOAR telescope, we decided to confirm this hypothesis by obtaining radial velocity measurements of the system over several months. Our spectra reveal a velocity variation with amplitude, period, and phase in accordance with the O-C diagram predictions. This corroboration demonstrates that the rapid pulsations of hot subdwarf B stars can be adequate clocks for the discovery of binary companions via the pulse timing method.

Accepted for publication in ApJ Letters; 5 pages, 2 figures, 3 tables; uses emulateapj

References in corpus (3)

• The MUCHFUSS project - Searching for hot subdwarf binaries with massive unseen companions: Survey, target selection and atmospheric parameters
• EXOTIME: searching for planets around pulsating subdwarf B stars
• Fortnightly Fluctuations in the O-C Diagram of CS 1246

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