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L. Lin, W. Herbst (Wesleyan U.)
We present the results of spot modeling analysis of 409 T Tauri stars in the Orion Nebula Cluster. Light curves are available from data obtained by Herbst, Bailer-Jones & Mundt (ApJ 554, L197) using the Wide Field Imager on the MPG/ESO 2.2 m telescope at La Silla, Chile. The spot model is adapted from Dorren (ApJ 320, 756) and employs the simplifying assumption of a single spot with circular shape. We fit the light curves using the Levenberg-Marquardt least squares minimization technique and infer the spot latitude, spot size, and the inclination of the stellar rotation axis to the line of sight. A Monte Carlo technique is used to obtain confidence limits on these parameters. We circumvent the issue of parameter degeneracy (which results from a coupling of inclination and spot latitude) in a statistical way by assuming randomly oriented stellar rotation axes. Our results provide new evidence in support of the existence of large, high latitude spots on these stars, as has been observed on other WTTS using Doppler imaging, and as is predicted by recent theory. Some results of an extension of our modeling to allow for two spots in opposite hemispheres will also be presented. This work was supported by a grant from NASA through its Origins program and by the Christian A. Johnson apprenticeship program of Wesleyan University.
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.