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arXiv · 1602.01575

An M dwarf Companion to an F-type Star in a young main-sequence binary

Ph. Eigmüller·J. Eislöffel·Sz. Csizmadia·H. Lehmann·A. Erikson·M. Fridlund·M. Hartmann·A. Hatzes·Th. Pasternacki·H. Rauer·A. Tkachenko·H. Voss
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Abstract

Only a few well characterized very low-mass M dwarfs are known today. Our understanding of M dwarfs is vital as these are the most common stars in our solar neighborhood. We aim to characterize the properties of a rare F+dM stellar system for a better understanding of the low-mass end of the Hertzsprung-Russel diagram. We used photometric light curves and radial velocity follow-up measurements to study the binary. Spectro- scopic analysis was used in combination with isochrone fitting to characterize the primary star. The primary star is an early F-type main-sequence star with a mass of (1.493 +- 0.073) Msun and a radius of (1.474 +- 0.040) Rsun. The companion is an M dwarf with a mass of (0.188 +- 0.014) Msun and a radius of (0.234 +- 0.009) Rsun. The orbital period is (1.35121 +- 0:00001)d. The secondary star is among the lowest-mass M dwarfs known to date. The binary has not reached a 1:1 spin-orbit synchronization. This indicates a young main-sequence binary with an age below ~250 Myrs. The mass-radius relation of both components are in agreement with this finding.

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Ph. Eigmüller, J. Eislöffel, Sz. Csizmadia, H. Lehmann, A. Erikson, M. Fridlund, M. Hartmann, A. Hatzes, Th. Pasternacki, H. Rauer, A. Tkachenko, H. Voss. 2016-02-04. An M dwarf Companion to an F-type Star in a young main-sequence binary. https://doi.org/10.3847/0004-6256/151/3/84

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