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 2.4 m 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^{+3.5}_{-3.1} pc, which implies that its radius and mass are ~0.0106 R_{solar} and 0.71 M_{solar}, respectively. GD 362 is not as massive as initially thought (1.2 M_{solar}). Our results are entirely consistent with the distance and mass estimates (52.2 pc and 0.73 M_{solar}) 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{\gt}0.9 M_{solar} that are known to host circumstellar dust disks. Based on observations obtained at the Michigan-Dartmouth-MIT (MDM) Observatory, operated by Dartmouth College, Ohio State University, Columbia University, the University of Michigan, and Ohio University.