Short-period Heartbeat Binaries from TESS Full-Frame Images

Abstract

We identify $240$ short-period ($P \lesssim 10$ days) binary systems in the TESS data, $180$ of which are heartbeat binaries (HB). The sample is mostly a mix of A and B-type stars and primarily includes eclipsing systems, where over $30\%$ of the sources with primary and secondary eclipses show a secular change in their inter-eclipse timings and relative eclipse depths over a multi-year timescale, likely due to orbital precession. The orbital parameters of the population are estimated by fitting a heartbeat model to their phase curves and Gaia magnitudes, where the model accounts for ellipsoidal variability, Doppler beaming, reflection effects, and eclipses. We construct the sample's period-eccentricity distribution and find an eccentricity cutoff (where $e \rightarrow 0$) at a period $1.7$ days. Additionally, we measure the periastron advance rate for the $12$ of the precessing sources and find that they all exhibit prograde apsidal precession, which is as high as $9^{\circ}$ yr$^{-1}$ for one of the systems. Using the inferred stellar parameters, we estimate the general relativistic precession rate of the argument of periastron for the population and expect over $30$ systems to show a precession in excess of $0.3^{\circ}$ yr$^{-1}$