SDSS J1152+0248: An eclipsing double white dwarf from the Kepler K2 campaign

TL;DR

This paper reports the discovery and detailed analysis of the sixth known eclipsing double white dwarf system, SDSS J1152+0248, using Kepler K2 data combined with ground-based observations, providing insights into their physical properties and evolutionary states.

Contribution

It presents the first detailed characterization of SDSS J1152+0248, including mass, radius, and age estimates for both white dwarfs, using combined photometric and spectroscopic data.

Findings

Primary WD: mass 0.47 Msun, radius 0.0197 Rsun, age 52 Myr.

Secondary WD: likely DA type, mass 0.44 Msun, radius 0.0223 Rsun, age 230 Myr.

System is a near twin of CSS 41177.

Abstract

We report the discovery of the sixth known eclipsing double white dwarf (WD) system, SDSS J1152+0248, with a 2.3968 +/- 0.0003 h orbital period, in data from the Kepler Mission's K2 continuation. Analysing and modelling the K2 data together with ground-based fast photometry, spectroscopy, and radial-velocity measurements, we determine that the primary is a DA-type WD with mass M1 = 0.47 +/- 0.11 Msun, radius R1 = 0.0197 +/- 0.0035 Rsun, and cooling age t1 = 52 +/- 36 Myr. No lines are detected, to within our sensitivity, from the secondary WD, but it is likely also of type DA. Its central surface brightness, as measured from the secondary eclipse, is 0.31 of the primary's surface brightness. Its mass, radius, and cooling age, respectively, are M2 = 0.44 +/- 0.09 Msun, R2 = 0.0223 +0.0064 -0.0050 Rsun, and t2 = 230 +/- 100 Myr. SDSS J1152+0248 is a near twin of the double-lined eclipsing WD system CSS 41177.