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[71.09] Testing Pre-Main-Sequence Stellar Evolution Theory: Discovery and Analysis of a Young, Low-Mass Eclipsing Binary

K.G. Stassun, N. Stroud, R.D. Mathieu (University of Wisconsin)

We present a preliminary analysis of a previously unknown, low-mass, pre-main-sequence (PMS), double-lined spectroscopic, eclipsing binary system in Orion. Eclipsing binaries provide powerful tests of stellar evolutionary models because stellar masses and radii are determined in a distance-independent way. Only four other PMS eclipsing binaries are presently known.

We present WIYN and HET spectroscopy from which we determine a double-lined orbit solution. We also present multi-epoch, multi-band photometric light curves which we model to derive key system parameters such as inclination and the ratio of stellar effective temperatures. With the addition of T_{\rm eff} for the primary (determined from our HET spectra), all system parameters are determined.

The primary and secondary masses are measured to be 1.0 M_\odot and 0.7 M_\odot, respectively. Thus the secondary in this system is the lowest mass star yet discovered in a PMS eclipsing binary.

We also give an update on our program to discover and analyze additional PMS eclipsing binaries as sensitive tests of PMS stellar evolution, particularly among very low-mass stars.

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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.