Brown dwarf 3rd body around FY Boo

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Brown dwarf 3rd body around FY Boo

Post by Edasich on Tue Jun 08, 2010 3:06 pm

No full paper though.

Photometric Analysis of the Very Short Period Solar Type Binary, FY Bootis

We present a BVRcIc photometric analyses of the very short period eclipsing binary, FY Bootis. Our observations were taken with the 0.81-m Lowell Reflector on March 10-14 2009. A period study and a light curve solution is presented.The light curves were premodeled with Binary 3.0, then solved with the 2004 version Wilson code with intermediate integrations performed with PHOEBE. Our modeled light curves included 107 B, 109 V, 95 R and 98 I individual CCD observations taken with the 2K X 2K NASACAM. A hotter star modeling temperature of 4750 K was chosen after considering 2MASS J-H and H-K values and the Rucinski (1994) period color relation. These gave spectral types in the K0-K5V range.Six mean times of minimum light were determined, including HJDMin I= 2454901.9711 (0.0022)d, 2454902.9350 (0.0024)d, 2454904.8587 (0.0002)d, 2454905.8304 (0.0002)d and HJDMin II=2454904.9774 (0.0007)d, 2454905.9491 (0.0002)d. Some 30 minima from the literature were included with ours to reveal a sinusoidal ephemeris: HJD Min I =2454904.8646 (0.0018)d + 0. 24116(0.00158)*E +(0.00160.00004)sin [(0.000510.00006)*E-(0.40.6)]. The period of oscillation is 81 years with an amplitude of 0.2 AU in light travel time, assuming the orbital inclination of a third component is identical to the main binary orbit. The third body has 0.05 solar masses.Our Wilson Code analysis of FY Boo revealed it to be a W-type contact binary (the less massive component is the hotter) and a mass ratio of 2.5. The system parameters included a fill-out of 0.11, a component temperature difference of 200 K and an inclination of 82o. One large 68o magnetic region was modeled on the hotter companion with an average temperature of 0.96 times that of the photosphere. We wish to thank the American Astronomical Society for supporting this research through its small research grant program.
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Edasich
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