AAS 207th Meeting, 8-12 January 2006
Session 11 Binary Models and Parameters
Poster, Monday, 9:20am-7:00pm, January 9, 2006, Exhibit Hall

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[11.03] Physical Orbit for Lam Vir and Testing of Stellar Evolution Models

M. Zhao, J. D. Monnier (Univ. of Michigan), G. Torres (Harvard-Smithonian Center for Astrophysics), E. Pedretti (Univ. of Michigan), R. Millan-Gabet (Michelson Science Center, Caltech), J.-P. Berger (Labrotoire d'Astrophysique de Grenoble), W. A. Traub (Harvard-Smithonian Center for Astrophysics), F.P. Schloerb (Univ. of Massachusetts at Amherst)

Lambda Virginis is a well-known double-lined spectroscopic Am binary with the interesting property that both stars are very similar in abundance but one is sharp-lined and the other is broad-lined. The differing rotation rates and the unusual metallic-lined nature of this system presents a unique opportunity to test stellar evolution models. In this poster, we present high resolution observations of Lam Vir, taken with the Infrared-Optical Telescopes Array (IOTA) between 2003 and 2005. By combining our interferometric data with double-lined radial velocity data, we determined for the first time the physical orbit of Lam Vir, as well as the orbital parallax of the system. In addition, the masses of the two components are determined with 1% and 1.5% errors respectively. Our preliminary result from comparison with stellar evolution models suggests a discrepancy between Lam Vir and standard models.


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