Searching for GEMS: Discovery of the Nearby Post-Common-Envelope Binary System TIC-460388167

TL;DR

This paper reports the discovery and detailed characterization of a nearby eclipsing post-common-envelope binary system, TIC-460388167, providing insights into the system's stellar components and orbital dynamics.

Contribution

The study presents the first velocity-resolved profile for a PCEB secondary and characterizes TIC-460388167 as one of the coolest and longest period systems known.

Findings

White dwarf temperature of 7607 K and radius 0.0131 R_sun.

M dwarf with temperature 3151 K and radius 0.327 R_sun.

White dwarf mass of 0.61 M_sun.

Abstract

Short-period white dwarf+main-sequence binaries are Post-Common-Envelope Binaries (PCEB) that have survived a common envelope phase. Such systems, if detached and eclipsing, enable precise measurements of the constituent stars, providing a unique opportunity to probe the effects of the common envelope phase on the system. We report the discovery of one such nearby (57 pc) system, TIC-460388167, using a combination of multi-band photometric light curves and spectroscopic radial velocities. In addition to eclipses, the system exhibits a continuously variable light curve that we model as a combination of ellipsoidal variations and star spots. We determine a period $P$=0.63596258$\pm$0.00000012 d and inclination $i$=89.0$\pm$0.4 deg. The best-fitting model specifies a white dwarf with T$_1$=7607$\pm$127 K and radius R$_1$=0.0131$\pm$0.0003 $R_\odot$, which is eclipsed by a T$_2$=3151 $\pm$ 59 K, R$_2$=0.327$\pm$0.006 $R_\odot$ M dwarf. The white dwarf mass is 0.61$\pm$0.04 M$_\odot$. We present the first velocity resolved profile for a PCEB secondary and show that the rotation of the M-dwarf is synchronous with the orbital period, as expected. We compare the constituent stars to other PCEB systems and find TIC-460388167A is one of the coolest known white dwarfs in such systems. TIC-460388167 is among the longest period eclipsing PCEB systems known.