NGTS J214358.5−380102 – NGTS discovery of the most eccentric known eclipsing M-dwarf binary system. Issue 3 (8th April 2020)

• Record Type: Journal Article
• Authors: Acton, Jack S; Goad, Michael R; Raynard, Liam; Casewell, Sarah L; Jackman, James A G; Alexander, Richard D; Anderson, David R; Bayliss, Daniel; Bryant, Edward M; Burleigh, Matthew R; Belardi, Claudia; Cooke, Benjamin F; Eigmüller, Philipp; Gill, Samuel; Jenkins, James S; Lendl, Monika; Louden, Tom; McCormac, James; Moyano, Maximiliano; Nielsen, Louise D; Tilbrook, Rosanna H; Udry, Stéphane; Watson, Christopher A; West, Richard G; Wheatley, Peter J; Vines, Jose I
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 494:Issue 3(2020)
• Page Start: 3950
• Page End: 3961
• Publication Date: 2020-04-08
• Subjects: binaries: eclipsing; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa928
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We present the discovery of NGTS J214358.5–380102, an eccentric M-dwarf binary discovered by the Next-Generation Transit Survey (NGTS). The system period of 7.618 d is greater than many known eclipsing M-dwarf binary systems. Its orbital eccentricity of $0.323^{+0.0014}_{-0.0037}$ is large relative to the period and semimajor axis of the binary. Global modelling of photometry and radial velocities indicates stellar masses of M A = $0.426 ^{+0.0056}_{-0.0049}$ M⊙, M B = $0.455 ^{+0.0058}_{-0.0052}$ M⊙ and stellar radii R A = $0.461 ^{+0.038}_{-0.025}$ R⊙, R B = $0.411 ^{+0.027}_{-0.039}$ R⊙, 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 spectral energy distribution 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 circularization of stellar orbits.