Spitzer Planet Limits around the Pulsating White Dwarf GD66

TL;DR

This study uses Spitzer infrared observations and pulsation timing to search for planets around the white dwarf GD66, setting upper mass limits and exploring detection methods.

Contribution

First combined pulsation timing and infrared flux analysis to constrain planetary companions around a white dwarf.

Findings

No strong evidence of a planet was detected.

Upper mass limit of 5-7 Jupiter masses for potential companions.

Pulsation timing suggests a possible planet > 2.4 Jupiter masses.

Abstract

We present infrared observations in search of a planet around the white dwarf, GD66. Time-series photometry of GD66 shows a variation in the arrival time of stellar pulsations consistent with the presence of a planet with mass > 2.4Mj. Any such planet is too close to the star to be resolved, but the planet's light can be directly detected as an excess flux at 4.5um. We observed GD66 with the two shorter wavelength channels of IRAC on Spitzer but did not find strong evidence of a companion, placing an upper limit of 5--7Mj on the mass of the companion, assuming an age of 1.2--1.7Gyr.