Dynamical mass determination and partial eclipses of the heartbeat star HD 181793

Laura E. Uronen*, Andrew Collier Cameron, Thomas G. Wilson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


We identify the bright Am-type star HD 181793 to be a previously-unknown eclipsing, chemically peculiar heartbeat binary, the second of its kind known. The system carries an orbital period of P = 11.47578275 ± 0.00000055 days. We use TESS photometry and LCOGT NRES radial velocity data to build a self-consistent orbital model and determine the fundamental stellar characteristics of the primary. We use a spectral separation method to unveil the secondary and measure the masses of both stars. The radial velocity amplitude of the primary, K1 = 47.41+0.13-0.12 km s-1, gives a mass M1 = 1.57 ± 0.01 M⊙. The secondary radial velocity amplitude K2 = 84.95+0.12-0.09 km s-1 yields a mass ratio $q = 0.558 ± 0.002$ and a secondary mass M2 = 0.87 ± 0.01 M⊙. From the spectral energy distribution and Gaia parallax we find a radius R1 = 2.04 ± 0.05 R⊙. The grazing transit profile and spectroscopic luminosity ratio indicate R2 = 1.04+0.15-0.10 R⊙, suggesting an early-K spectral type. We show that the heartbeat feature in the TESS light curve can be explained by time-varying ellipsoidal variation, driven by the orbital eccentricity of e = 0.3056+0.0024-0.0026, and relativistic beaming of the light of the primary. We find no evidence of tidally-excited oscillations.
Original languageEnglish
JournalMonthly Notices of the Royal Astronomical Society
Publication statusAccepted/In press - 16 Jun 2024


  • Stars: binaries: eclipsing
  • Stars: chemically peculiar
  • Stars: fundamental parameters


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