Author:

Keywords:

Science & Technology, Physical Sciences, Astronomy & Astrophysics, binaries: close, binaries: eclipsing, stars: evolution, stars: low-mass, LOW-MASS STARS, M-CIRCLE-DOT, PARSEC EVOLUTIONARY TRACKS, TRANSITING M-DWARF, ECLIPSING BINARY, STELLAR EVOLUTION, RADIUS DETERMINATIONS, VARIABILITY SURVEY, ACCURATE MASSES, TIDAL-EVOLUTION, astro-ph.SR, 0201 Astronomical and Space Sciences, 5101 Astronomical sciences, 5107 Particle and high energy physics

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. Spectroscopic 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) M⊙ and a radius of (1.474 ± 0.040) R⊙. The companion is an M dwarf with a mass of (0.188 ± 0.014) M⊙ and a radius of (0.234 ± 0.009) R⊙. The orbital period is (1.35121 ± 0.00001) days. 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 Myr. The mass-radius relation of both components are in agreement with this finding.