An extreme-mass ratio, short-period eclipsing binary consisting of a B dwarf primary and a pre-main-sequence M star companion discovered by KELT

Daniel J. Stevens, George Zhou, Marshall C. Johnson, Aaron C. Rizzuto, Joseph E. Rodriguez, Allyson Bieryla, Karen A. Collins, Steven Villanueva, Jason T. Wright, B. Scott Gaudi, David W. Latham, Thomas G. Beatty, Michael B. Lund, Robert J. Siverd, Adam L. Kraus, Patcharapol Wachiraphan, Perry Berlind, Michael L. Calkins, Gilbert A. Esquerdo, John F. KielkopfRudolf B. Kuhn, Mark Manner, Joshua Pepper, Keivan G. Stassun

Research output: Contribution to journalArticlepeer-review

Abstract

We present the discovery of KELT J072709 + 072007 (HD 58730), a very low mass ratio (q ≡ M2/M1 ≈ 0.07) eclipsing binary (EB) identified by the Kilodegree Extremely Little Telescope (KELT) survey. We present the discovery light curve and perform a global analysis of four high-precision ground-based light curves, the Transiting Exoplanets Survey Satellite (TESS) light curve, radial velocity (RV) measurements, Doppler Tomography (DT) measurements, and the broad-band spectral energy distribution. Results from the global analysis are consistent with a fully convective (M2 = 0.22 ± 0.02 M☉) M star transiting a late-B primary (M1 = 3.34+000709 M☉ and Teff,1 = 11960+430520 K). We infer that the primary star is 183+3330 Myr old and that the companion star's radius is inflated by 26 ± 8 per cent relative to the predicted value from a low-mass isochrone of similar age. We separately and analytically fit for the variability in the out-of-eclipse TESS phase curve, finding good agreement between the resulting stellar parameters and those from the global fit. Such systems are valuable for testing theories of binary star formation and understanding how the environment of a star in a close-but-detached binary affects its physical properties. In particular, we examine how a star's properties in such a binary might differ from the properties it would have in isolation.

Original languageEnglish (US)
Pages (from-to)3775-3791
Number of pages17
JournalMonthly Notices of the Royal Astronomical Society
Volume499
Issue number3
DOIs
StatePublished - Dec 1 2020

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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