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Astron. Astrophys. 341, L63-L66 (1999)

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Letter to the Editor

GJ 2069A, a new M dwarf eclipsing binary *

X. Delfosse 1,2, T. Forveille 2, M. Mayor 1, M. Burnet 1 and C. Perrier 2

1 Observatoire de Genève, 51 Ch des Maillettes, CH-1290 Sauverny, Switzerland
2 Observatoire de Grenoble, 414 rue de la Piscine, Domaine Universitaire de St Martin d'Hères, F-38041 Grenoble, France

Received 9 July 1998 / Accepted 2 December 1998


We have discovered a third detached M dwarf eclipsing binary system, for which we present an accurate radial velocity orbit and a preliminary light curve. From those data, we derive individual masses (0.433 and 0.397 [FORMULA]) with 0.4% accuracy, the most accurate to date for M dwarfs. Both stars are clearly sub-luminous for their mass, compared with solar metallicity stellar models or empirical mass-luminosity relations. Their spectral types are also later than expected. This indicates a metal-rich composition ([FORMULA]). An infrared light curve and a more accurate trigonometric parallax would make this system a stringent test of our understanding of M dwarfs.

Key words: stars: binaries: eclipsing – stars: binaries: general – stars: binaries: spectroscopic – stars: binaries: visual – stars: low-mass, brown dwarfs

* Based on observations obtained at the Observatoire de Haute Provence (CNRS) and at the European Southern Observatory

Send offprint requests to: Xavier Delfosse (Xavier.Delfosse@obs.unige.ch)

© European Southern Observatory (ESO) 1999

Online publication: December 16, 1998