AAS 207th Meeting, 8-12 January 2006
Session 13 Interacting Binaries
Poster, Monday, 9:20am-7:00pm, January 9, 2006, Exhibit Hall

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[13.12] Examining an Overcontact Binary with Changing Period

B. Purinton (U. of Massachusetts-Amherst & Maria Mitchell Obs.), R. E. Wilson (U. of Florida & Maria Mitchell Obs.)

This project was conducted in order to shed light on the little studied overcontact binary V401 Cygni, especially in regard to its changing period. Combining B and V band light curves by A. Purgathofer (1964) and radial velocity curves by S. Rucinksi et al. (2002), simultaneous solutions with a light/velocity curve model (Wilson and Devinney, 1971; Wilson, 1979) follow the data closely, except for parts of the light curve maximum preceding the annular primary eclipse. The complete eclipse phases are very brief. The consensus photometric/spectroscopic mass ratio of 0.276 agrees with that of Rucinski et al., formally being only 1.1 standard deviation smaller, and with most of the weight in the light curves. The over-contact level is 0.30. The inclination was found to be 79.7° and the radial velocity of the center of mass is 20.4 km/s. The gradually increasing period was explored, aided by data collected at www.as.ap.krakow.pl/o-c/index.php3. Observations from Flagstaff, AZ, taken in May 2005 on the 31-in optical telescope in U,B,V,R,I bands, are being incorporated in the solution to study the period change. These light curves deviate from Purgathofer's observations in the primary eclipse for unknown reasons. The data will be obtainable at the January 2006 AAS meeting or at www.mmo.org. This project was supported by the NSF grants AST-0354056 and 0307561 and the Nantucket Maria Mitchell Association.

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

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