AAS 205th Meeting, 9-13 January 2005
Session 11 Brown Dwarfs and Exoplanets
Poster, Monday, January 10, 2005, 9:20am-6:30pm, Exhibit Hall

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[11.09] Photometry of the suspected brown dwarf + K star eclipsing binary 2MASS J0516288+260738

A. J. Bayless, J. A. Orosz (San Diego State University)

Recently, the serendipitous discovery of a new eclipsing low mass system was announced (Schuh et al.\ 2003). The system, known as 2MASS J0516288+260738 (hereafter J0516), has an eclipse period of 1.29395 days. The optical spectrum is single-lined, showing only a K7V star. From an analysis of the light curves, Schuh et al.\ (2003) conclude the companion star to the K7V star is a brown dwarf since the mass ratio is extreme (\approx 10:1) while the ratio of radii is near unity. If this discovery is confirmed, it would be the first known example of an eclipsing binary with a brown dwarf component. Thus J0516 is potentially a very important system for the study of very low mass stars and substellar objects.

We obtained V, R, and I light curves of J0516 using the 1m telescope at Mount Laguna Observatory (MLO, located in eastern San Diego County). The source was observed extensively during the months of January, February, March, and October 2004. In contrast to what Schuh et al.\ (2003) observed, we found some variability in the out-of-eclipse phases in the January-March data. The light curves from October showed essentially no out-of-eclipse varibility, similar to what Schuh et al.\ (2003) found.

We modelled the light curves from October using our ELC code (Orosz & Hauschildt 2000) with updated model atmospheres for low mass main sequence stars and substellar objects (Hauschildt private communication). We discuss the results of our modelling and discuss the possible nature of the unseen companion.

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© 2004. The American Astronomical Society.