SSP seminar
 

Rapid Orbital Decay in the 12.75-Minute WD+WD Binary J0651+2844

JJ Hermes (University of Texas at Austin)

Monday 29 October 2012, 12:00 pm
Pratt Conference Room, 60 Garden Street

We recently reported the signature of orbital decay in the 12.75-min WD+WD binary SDSS J065133.338+284423.37 (hereafter J0651). Our photometric observations over a 13-month baseline indicate the orbital period is changing at a rate of (-9.8 +/- 2.8) x 10^{-12} s/s (or -0.31 +/- 0.09 ms/yr), consistent with the expectation of -0.26 +/- 0.05 ms/yr from general relativity. J0651 is currently the second-loudest gravitational wave source known in the milli-hertz range and it is a verification source for future missions aimed at directly detecting gravitational radiation. Our work establishes the feasibility of monitoring this system's orbital period decay at optical wavelengths. Tidal effects will also increase the rate of orbital decay in J0651, especially if the primary is well synchronized. These tides depend sensitively on the interior of the extremely low-mass (ELM) WD. Asteroseismology is one way to independently probe the interior of these objects, and I will discuss our recent discovery of the first (and now second and third) pulsating He-core, ELM WDs.

 
 

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