paper

NGTS J214358.5-380102 -- NGTS discovery of the most eccentric known eclipsing M-Dwarf binary system

arXiv:2003.14314 · doi:10.1093/mnras/staa928

Abstract

We present the discovery of NGTS J214358.5-380102, an eccentric M-dwarf binary discovered by the Next Generation Transit Survey. The system period of 7.618 days is greater than many known eclipsing M-dwarf binary systems. Its orbital eccentricity of $0.32 3_{- 0.0037}^{+ 0.0014}$ , is large relative to the period and semi-major axis of the binary. Global modelling of photometry and radial velocities indicate stellar masses of $M_{A}$ = $0.42 6_{- 0.0049}^{+ 0.0056}$ , $M_{B}$ = $0.45 5_{- 0.0052}^{+ 0.0058}$ and stellar radii $R_{A}$ = $0.46 1_{- 0.025}^{+ 0.038}$ $R_{B}$ = $0.41 1_{- 0.039}^{+ 0.027}$ , respectively. Comparisons with stellar models for low mass stars show that one star is consistent with model predictions whereas the other is substantially oversized. Spectral analysis of the system suggests a primary of spectral type M3V, consistent with both modelled masses and radii, and with SED fitting of NGTS photometry. As the most eccentric eclipsing M-dwarf binary known, NGTS J214358.5-380102 provides an interesting insight into the strength of tidal effects in the circularisation of stellar orbits.

Accepted for Publication in MNRAS