A Bright Short Period M-M Eclipsing Binary from the KELT Survey: Magnetic Activity and the Mass–Radius Relationship for M Dwarfs

LUBIN, JACK B.; RODRIGUEZ, JOSEPH E.; ZHOU, GEORGE; CONROY, KYLE E.; STASSUN, KEIVAN G.; COLLINS, KAREN; STEVENS, DANIEL J.; LABADIE-BARTZ, JONATHAN; STOCKDALE, CHRISTOPHER; MYERS, GORDON; COLÓN, KNICOLE D.; BENTO, JOAO; KEHUSMAA, PETRI; PETRUCCI, ROMINA; JOFRÉ, EMILIANO; QUINN, SAMUEL N.; LUND, MICHAEL B.; KUHN, RUDOLF B.; SIVERD, ROBERT J.; BEATTY, THOMAS G.; HARLINGTEN, CAISEY; PEPPER, JOSHUA; GAUDI, B. SCOTT; JAMES, DAVID; JENSEN, ERIC L. N.; REICHART, DANIEL; KEDZIORA-CHUDCZER, LUCYNA; BAILEY, JEREMY; MELVILLE, GRAEME

The Astrophysical Journal

IOP Publishing for the American Astronomical Society

Año: 2017 vol. 844

We report the discovery of KELT J041621-620046, a moderately bright (J ∼ 10.2) M-dwarf eclipsing binarysystem at a distance of 39 ± 3 pc. KELT J041621-620046 was first identified as an eclipsing binary usingobservations from the Kilodegree Extremely Little Telescope (KELT) survey. The system has a short orbital periodof ∼1.11 days and consists of components with M1 = 0.447-0.047 Msun and M2 = 0.399-0.042 Msun in nearly circular orbits. The radii of the two stars are R = 0.540-0.032 R and R = 0.453  0.017 R . Full system and orbitalproperties were determined (to ∼10% error) by conducting an EBOP (Eclipsing Binary Orbit Program) globalmodeling of the high precision photometric and spectroscopic observations obtained by the KELT Follow-up Network. Each star is larger by 17%?28% and cooler by 4%?10% than predicted by standard (non-magnetic) stellar models. Strong Hα emission indicates chromospheric activity in both stars. The observed radii and temperature discrepancies for both components are more consistent with those predicted by empirical relations that account for convective suppression due to magnetic activity.