AAS 207th Meeting, 8-12 January 2006
Session 186 Eclipsing Binaries
Poster, Thursday, 9:20am-4:00pm, January 12, 2006, Exhibit Hall

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[186.05] Light Curves and Analysis of the Eclipsing Binaries MT Her and DO And

D.H. Bradstreet, S.J. Sanders, J.R. Hargis (Eastern University)

New precision V & Rc light curves of the eclipsing binaries MT Her and DO And have been obtained using the 41-cm telescope at the Eastern University Observatory equipped with an SBIG ST-10XME CCD. MT Her (P = 0.4877 days, m = 11.8) has only one other published light curve (Budding & Murad 1989) and the coverage is scanty and incomplete. The system was observed on 12 nights from 16 May - 2 Jul 2005, accumulating approximately 890 observations in both V and Rc. Although the light curves give the appearance of a near-contact system as evidenced by the significant difference in eclipse depths, the out of eclipse light variations constrain the system to be overcontact. MT Her is an A-type overcontact binary that exhibits slightly asymmetric maxima which is modeled well with a single cool spot on the more massive star. Preliminary analysis indicates that it has a mass ratio q = 0.66, a large temperature difference of 1500 K between the two components, and a small fillout f = 0.10. A period study of all published times of minimum light will also be presented.

DO And (P = 1.3487 days, m = 12.5) is listed in the GCVS as having a period of 0.672 days. Haussler (1988) discovered that the actual period is twice that value and published the only existing light curve prior to our work. Haussler's light curve, although covering the entire cycle, contains significant scatter. DO And was observed on more than 20 nights through Sep - Nov 2005, accumulating more than 1200 observations in both V and Rc. Preliminary light curve models indicate a detached but close pair of slightly distorted stars with a temperature difference of approximately 2300 K.

The final results of the analyses of both systems will be presented.

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

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