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

Jack S. Acton, Michael R. Goad, Liam Raynard, Sarah L. Casewell, James A. G. Jackman, Richard D. Alexander, David R. Anderson, Daniel Bayliss, Edward M. Bryant, Matthew R. Burleigh, Claudia Belardi, Benjamin F. Cooke, Philipp Eigmüller, Samuel Gill, James S. Jenkins, Monika Lendl, Tom Louden, James McCormac, Maximiliano Moyano, Louise D. NielsenRosanna H. Tilbrook, Stéphane Udry, Christopher A. Watson, Richard G. West, Peter J. Wheatley, Jose I. Vines

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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 semi major axis of the binary. Global modelling of photometry and radial velocities indicates stellar masses of MA = 0.426 ^{+0.0056}_{-0.0049} M⊙,MB = 0.455 ^{+0.0058}_{-0.0052} M⊙ and stellar radii RA = $0.461 ^{+0.038}_{-0.025} R⊙, RB = 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.
Original languageEnglish
Pages (from-to)3950-3961
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
Early online date08 Apr 2020
Publication statusPublished - 01 May 2020


  • binaries: eclipsing

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