AAS 204th Meeting, June 2004
Session 5 Eclipsing Binaries and Friends
Poster, Monday, May 31, 2004, 9:20am-6:30pm, Ballroom

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[5.07] Analysis of the Extreme Mass Ratio, High Contact Eclipsing Binary, V802 Aquilae

R.G. Samec, M.W. Martin (Bob Jones University), D.R. Faulkner (University of South Carolina, Lancaster)

We present our observations and initial analysis of BVRI light curves of the solar type, high contact binary, V802 Aquilae [GSC 5119 948, \alpha(2000) = 18h 58m 54.82s, \delta(2000) = -03\degr 01' 11.5"]. The observations were taken on the evenings of 5, 6 and 8 June 2002, by RGS and DRF with the 0.9-m reflector at CTIO. Standard UBVRcIc filters were used. We took from 138 to 148 observations in each BVRI pass band and about 100 in U.

Mean epochs of minimum light for one primary eclipse, HJD = 2452431.82156 (81) as well as two secondary eclipses 2452434.89764 (11) and 2452432.75617 (21) were calculated. We calculated the following linear ephemeris:

J.D. Hel Min I = 2450300.43417 (69) + 0.26769479 (11) d*E. (2)

The light curves are shallow (0.35 mag in V) yet show a broad time of constant light (width about 0.1 phase) in the secondary eclipse. Its depressed primary maxima (about 0.06 mag in B) suggest the presence of heavy spot activity. Our Wilson code BVRI simultaneous solution of the instrumental magnitude light curves yields a mass ratio of M2/M1 = 0.16, and a fill-out 32.7 %. The temperature difference is T2-T1 = 136 K with the tiny secondary component having the higher mean surface temperature. A 20.2\degr cool spot was modeled on the primary component. Its longitude, co-latitude and temperature factor were 281\degr, 67\degr, and 0.915 respectively. Further results are presented.

The system is a part of a rare group of binaries with a very low mass secondary and high mass ratio that are near a phase of final coalescence into an FK Comae type star.

Much of the work was done by an undergraduate student, MWM. We wish to thank Cerro Tololo InterAmerican Observatory for their allocation of observing time, and the grant from NASA administered by the American Astronomical Society.

The author(s) of this abstract have provided an email address for comments about the abstract: ronsamec@msn.com

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