AAS 202nd Meeting, May 2003
Session 8 Binary Stars
Poster, Monday, May 26, 2003, 9:20am-6:30pm, West Exhibit Hall

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[8.08] The First Precision CCD Observations of the Near Contact Binary, UY Muscae

R. McKenzie, M. L. Stoddard, R. G. Samec (Astronomy Program, Bob Jones University), D. R. Faulkner (U of South Carolina, Lancaster)

As a part of our study of solar type stars with gas streams we observed UY Muscae [Star "y" (Oosterhoff, BAIN #148, 1928) GSC 8987 392, \alpha(2000) = 12h 30m 47s , \delta(2000) = -66\degr 01' 52.8"]. The observations were taken at CTIO in Chili with the 0.9-m reflector on 18, 19, 20, 23 May 2001, by RGS and DRF. The CFIM T2K CCD camera with standard UBVRcIc filters in quad mode were used. More than 200 observations were taken in each pass band. The stars (GSC 8987 1279 \alpha(2000) = 12h30m43.7s, \delta(2000) = -65\degr59'45") and (GSC 8987 1884, \alpha(2000) = 12h30m45.7s, \delta(2000) = -66\degr01'5") were used as comparison and check stars, respectively. Two mean epochs of minimum light were determined from primary and secondary eclipses, HJD = 2452047.6239(0.0017) and 2452049.5918(0.0005) . Standard errors are given in parentheses. We calculated the following ephemeris from our data:

HJD Tmin I = 2452047.6240(0.0003) + 0.562273(0.000151)d*E .

A UBVRI synthetic light curve solution was calculated using the Wilson Code. It indicates the primary (more massive) component is under-filling its Roche lobe [fill-out = 94.4(0.001) critical lobe. This is similar to an Algol system. The final parameters include a mass ratio, m2/m1 = 0.551(0.001) , and a temperature difference T1-T2 = 1280(3)K. Two spots were modeled: a stream spot with a temperature factor of 1.060(0.002) very near the L1 point of the primary component and a solar type dark spot of radius 25.2(0.3)\degr with a T factor of 0.970( 0.001). Large night to night variations in the light curve lead us to believe that the components are saturated with magnetic activity. It is possible that the system was previously in contact and is undergoing TRO oscillations. Our model indicates that the components are currently separating. Further results of this study will be presented. We wish to thank CTIO for their allocation of observing time, and a small research grant from the American Astronomical Society which supported this run.

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

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Bulletin of the American Astronomical Society, 35 #3
© 2003. The American Astronomical Soceity.