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arXiv · 1103.2354

The Shortest Period Detached Binary White Dwarf System

Mukremin Kilic·Warren R. Brown·S. J. Kenyon·Carlos Allende Prieto·J. Andrews·S. J. Kleinman·K. I. Winget·D. E. Winget·J. J. Hermes
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Abstract

We identify SDSS J010657.39-100003.3 (hereafter J0106-1000) as the shortest period detached binary white dwarf (WD) system currently known. We targeted J0106-1000 as part of our radial velocity program to search for companions around known extremely low-mass (ELM, ~ 0.2 Msol) WDs using the 6.5m MMT. We detect peak-to-peak radial velocity variations of 740 km/s with an orbital period of 39.1 min. The mass function and optical photometry rule out a main-sequence star companion. Follow-up high-speed photometric observations obtained at the McDonald 2.1m telescope reveal ellipsoidal variations from the distorted primary but no eclipses. This is the first example of a tidally distorted WD. Modeling the lightcurve, we constrain the inclination angle of the system to be 67 +- 13 deg. J0106-1000 contains a pair of WDs (0.17 Msol primary + 0.43 Msol invisible secondary) at a separation of 0.32 Rsol. The two WDs will merge in 37 Myr and most likely form a core He-burning single subdwarf star. J0106-1000 is the shortest timescale merger system currently known. The gravitational wave strain from J0106-1000 is at the detection limit of the Laser Interferometer Space Antenna (LISA). However, accurate ephemeris and orbital period measurements may enable LISA to detect J0106-1000 above the Galactic background noise.

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Mukremin Kilic, Warren R. Brown, S. J. Kenyon, Carlos Allende Prieto, J. Andrews, S. J. Kleinman, K. I. Winget, D. E. Winget, J. J. Hermes. 2011-03-11. The Shortest Period Detached Binary White Dwarf System. https://doi.org/10.1111/j.1745-3933.2011.01044.x

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