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R.G. Samec, T.S. Loflin (Bob Jones University), W. Van Hamme (Florida International Univ.)
We present light curve and periodicity analyses of the contact binary, AR Bootis. Our CCD observations were taken at the Southeastern Association for Research in Astronomy (SARA) observatory on Kitt Peak on 6, 10 May and 8 June 2004 in remote mode by RGS, and TSL with the 0.9-m reflector and the AP7 CCD. Standard UBVRcIc filters filters were used. AR Boo [GSC 1999 011, \alpha(2000)= 13h 48m 10.32s, \delta(2000)= +24\degr 55’ 27.9"] was discovered by Kurochkin (Astron. Tsirk 205, 1959). Its primary and secondary eclipse depths are 0.8 and 0.6 magnitudes in V, respectively. The comparison star was [GSC 1999 009, \alpha(2000)= 13h 48m 13.25s, \delta(2000)= +24\degr 55’ 55.00.3"].
About 130 observations in each of the BVRI pass bands were taken. Calibrations were done with AIPWIN by TSL. Three mean epochs of minimum light were computed: HJD Min I = 2453131.8527(±0.0002), 2453135.8183(±0.0013), and HJD Min II = 2453165.8238(±0.0003). The orbital study shows a clear quadratic trend in eclipse timings,
HJD Tmin I = 2450182.47774 ±(0.00040) d + 0.3448741816 ±(0.0000000686)*E + 0.000000000125 ± (0.000000000002)*E2, (1)
revealing a constant period increase.
An ephemeris for recent epochs of minimum light was also computed:
HJD Tmin I = 2453131.8512 ±(0.0004) + 0.344875996 ± (0.000000115) d*E. (2)
A synthetic light curve solution was calculated. The system is a W-type WUMa contact binary with a Roche-lobe fill-out of 17.5%. The computed mass ratio, M2/M1, is 1.945 ± 0.007 while the temperature difference, T1-T2, is 450 ± 8 K. An inclination of 74.8\degr ±0.1 was computed. A subluminous region was found at a longitude of 128\degr a colatitude of 90\degr with a radius of 20\degr and a temperature of 96% of that of the photosphere. Further information is presented.
Acknowledgements: We wish to thank the Southeastern Association for Research in Astronomy (SARA) for their allocation of observing time, as well as NASA and the American Astronomical Society for their continued support of our undergraduate research programs through their small research grants.
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Bulletin of the American Astronomical Society, 37 #2
© 2005. The American Astronomical Soceity.