Spitzer planet limits around the pulsating white dwarf GD66

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 ≥2.4M J. 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 4.5μm. We observed GD66 with the two shorter wavelength channels of the Infrared Array Camera on Spitzer but did not find strong evidence of a companion, placing an upper limit of 5-7M J on the mass of the companion, assuming an age of 1.2-1.7 Gyr. © 2009. The American Astronomical Society. All rights reserved.