The evolutionary history of GD1400, a white dwarf-brown dwarf binary

TL;DR

This paper studies the GD1400 binary system, combining radial velocity and photometry data to analyze the brown dwarf's temperature, pulsations, and evolutionary history, providing new insights into white dwarf-brown dwarf binaries.

Contribution

It presents new measurements and analysis of GD1400, revealing the brown dwarf's higher-than-expected temperature and discussing its evolutionary pathway, which advances understanding of such binary systems.

Findings

Brown dwarf's brightness temperature is higher than previously thought.

White dwarf's pulsations are analyzed alongside irradiation effects.

The evolutionary pathway of GD1400 is discussed in context with similar systems.

Abstract

GD1400AB was one of the first known white dwarf$+$brown dwarf binaries, and is the only one of these systems where the white dwarf is a ZZ Ceti pulsator. Here we present both radial velocity measurements and time series photometry, analysing both the white dwarf pulsations and the effects of irradiation on the brown dwarf. We find the brightness temperatures of 1760$/pm$10 K for the night side and 1860$/pm$10 K for the day side indicate the brown dwarf is hotter than spectra have previously suggested, although brightness temperatures calculated using a larger radius for the brown dwarf are consistent with previously determined spectral types. We also discuss the likely evolutionary pathway of this binary, and put its common envelope phase into context with the other known systems.