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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[186.01] Light Curves and Analysis of the Overcontact Binaries GN Boo, V608 Cas and V789 Cyg

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

New precision V & Rc light curves of the eclipsing overcontact binaries GN Boo, V608 Cas and V789 Cyg have been obtained using the 41-cm telescope at the Eastern University Observatory equipped with an SBIG ST-10XME CCD. GN Boo (P = 0.3016 days, m = 10.8) has only one published light curve (Blattler & Diethelm 2001a) which is noisy and had no subsequent analysis. The system was observed on 5 nights from 3 - 14 Mar 2005, accumulating approximately 750 observations in both V and Rc. Because the previously published light curve had rather large excursions in light, it was hoped that GN Boo would display total eclipses, which in fact it does. Preliminary analysis indicates that it has a mass ratio of q = 0.33, a temperature difference of 360 K between the two components, and a fillout f = 0.21. The maxima are markedly asymmetric which was modeled with a cool spot region.

V608 Cas (P = 0.3804 days, m = 12.0) was observed by Blattler & Diethelm (2001b) who published a complete but noisy light curve. Although chosen for study because its published light curve suggested possible totality in the eclipses, this did not turn out to be the case. V608 Cas was observed on 3 nights from 18 Oct - 7 Nov 2004, accumulating approximately 560 observations in both V and Rc. Preliminary light curve models indicate an overcontact system with a small temperature difference between the two stars of approximately 200 K and a fillout f = 0.25.

V789 Cyg (P = 0.4483, m = 13.3) is classified in the GCVS as an RR Lyrae variable, and the system was presented as such by Ponce & Sharp (2000). However their light curve looked to us very much like a W UMa light curve folded upon itself with half the true period, and so this system was observed in V and Rc on 8 nights from 27 Jun - 21 Jul 2004. The resulting light curves confirmed the overcontact nature of the system, and the modeling is still in progress.

The final results of the analyses of these 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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