* Astronomy

Title: Visual orbit of GJ 164 AB
Authors: Frantz Martinache, Barbara Rojas-Ayala, Michael J. Ireland, James P. Lloyd, Peter G. Tuthill

We report seven successful observations of the astrometric binary GJ 164 AB system with aperture masking interferometry. The companion, with a near infrared contrast of 5:1 was detected beyond the formal diffraction limit. Combined with astrometric observations from the literature, these observations fix the parallax of the system, and allow a model-independent mass determination of both components. We find the mass of GJ 164B to be  0.086 ± 0.007 solar masses. An infrared spectroscopic study of a sample of M-Dwarfs outlines a method for calibrating metallicity of M-Dwarfs. Results from the newly commissioned TripleSpec spectrograph reveal that the GJ 164 system is at least of Solar metallicity. Models are not consistent with colour and mass, requiring a very young age to accommodate a secondary too luminous, a scenario ruled out by the kinematics.

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