Characterizing the Cool KOIs. VII. Refined Physical Properties of the Transiting Brown Dwarf LHS 6343 C

TL;DR

This paper refines the physical properties of the transiting brown dwarf LHS 6343 C using Kepler data, radial velocities, and adaptive optics, and introduces a model-independent method to determine stellar and companion parameters.

Contribution

It presents a new method to measure the mass and radius of transiting objects directly without relying on stellar models.

Findings

Measured the mass of LHS 6343 C as 62.1 +/- 1.2 M_Jup.

Determined the radius of LHS 6343 C as 0.783 +/- 0.011 R_Jup.

Achieved a 3% and 2% precision in mass and radius measurements, respectively.

Abstract

We present an updated analysis of LHS 6343, a triple system in the Kepler field which consists of a brown dwarf transiting one member of a widely-separated M+M binary system. By analyzing the full Kepler dataset and 34 Keck/HIRES radial velocity observations, we measure both the observed transit depth and Doppler semiamplitude to 0.5% precision. With Robo-AO and Palomar/PHARO adaptive optics imaging as well as TripleSpec spectroscopy, we measure a model-dependent mass for LHS 6343 C of 62.1 +/- 1.2 M_Jup and a radius of 0.783 +/- 0.011 R_Jup. We detect the secondary eclipse in the Kepler data at 3.5 sigma, measuring e cos omega = 0.0228 +/- 0.0008. We also derive a method to measure the mass and radius of a star and transiting companion directly, without any reliance on stellar models. The mass and radius of both objects depend only on the orbital period, stellar density, reduced semimajor axis, Doppler semiamplitude, eccentricity, and inclination, as well as the knowledge that the primary star falls on the main sequence. With this method, we calculate a model-independent mass and radius for LHS 6343 C to a precision of 3% and 2%, respectively.