GJ 3236: a new bright, very low-mass eclipsing binary system discovered by the MEarth observatory
Abstract
We report the detection of eclipses in GJ 3236, a bright (I = 11.6) very low mass binary system with an orbital period of 0.77 days. Analysis of light- and radial velocity curves of the system yielded component masses of 0.38 +/- 0.02 and 0.28 +/- 0.02 Msol. The central values for the stellar radii are larger than the theoretical models predict for these masses, in agreement with the results for existing eclipsing binaries, although the present 5% observational uncertainties limit the significance of the larger radii to approximately 1 sigma. Degeneracies in the light curve models resulting from the unknown configuration of surface spots on the components of GJ 3236 currently dominate the uncertainties in the radii, and could be reduced by obtaining precise, multi-band photometry covering the full orbital period. The system appears to be tidally synchronized and shows signs of high activity levels as expected for such a short orbital period, evidenced by strong Halpha emission lines in the spectra of both components. These observations probe an important region of mass-radius parameter space around the predicted transition to fully-convective stellar interiors, where there are a limited number of precise measurements available in the literature.
Cite
@article{arxiv.0906.4365,
title = {GJ 3236: a new bright, very low-mass eclipsing binary system discovered by the MEarth observatory},
author = {Jonathan Irwin and David Charbonneau and Zachory K. Berta and Samuel N. Quinn and David W. Latham and Guillermo Torres and Cullen H. Blake and Christopher J. Burke and Gilbert A. Esquerdo and Gabor Furesz and Douglas J. Mink and Philip Nutzman and Andrew H. Szentgyorgyi and Michael L. Calkins and Emilio E. Falco and Joshua S. Bloom and Dan L. Starr},
journal= {arXiv preprint arXiv:0906.4365},
year = {2010}
}
Comments
14 pages, 5 figures, 10 tables, emulateapj format. Accepted for publication in ApJ