Direct Distance Measurement to the Dusty White Dwarf GD 362

Abstract

We present trigonometric parallax observations of GD 362 obtained over seven epochs using the MDM 2.4m Hiltner Telescope. The existence of a dust disk around this possibly massive white dwarf makes it an interesting target for parallax observations. The measured parallax for GD 362 places it at a distance of 50.6 pc, which implies that its radius and mass are ~ 0.0106 Rsun and 0.71 Msun, respectively. GD 362 is not as massive as initially thought (1.2Msun). Our results are entirely consistent with the distance and mass estimates (52.2 pc and 0.73 Msun) by Zuckerman et al., who demonstrated that GD 362 has a helium dominated atmosphere. Dropping GD 362 from the list of massive white dwarfs, there are no white dwarfs with M > 0.9 Msun that are known to host circumstellar dust disks.