The Discovery of a Debris Disk Around the DAV White Dwarf PG 1541+651

TL;DR

This paper reports the discovery of a warm debris disk around the pulsating white dwarf PG 1541+651, identified through infrared excess and confirmed with follow-up observations, expanding understanding of nearby dusty white dwarfs.

Contribution

The study presents the first detection of a debris disk around PG 1541+651, a pulsating white dwarf, using infrared observations, and highlights the potential for discovering more such disks around nearby white dwarfs.

Findings

Detected infrared flux excess indicating a debris disk

Confirmed the disk with follow-up infrared spectroscopy and photometry

Demonstrated that nearby dusty white dwarfs are more common than previously known

Abstract

To search for circumstellar disks around evolved stars, we targeted roughly 100 DA white dwarfs from the Palomar Green survey with the Peters Automated Infrared Imaging Telescope (PAIRITEL). Here we report the discovery of a debris disk around one of these targets, the pulsating white dwarf PG 1541+651 (KX Draconis, hereafter PG1541). We detect a significant flux excess around PG1541 in the K-band. Follow-up near-infrared spectroscopic observations obtained at the NASA Infrared Telescope Facility (IRTF) and photometric observations with the warm Spitzer Space Telescope confirm the presence of a warm debris disk within 0.13-0.36 Rsun (11-32x the stellar radius) at an inclination angle of 60deg. At Teff = 11880 K, PG1541 is almost a twin of the DAV white dwarf G29-38, which also hosts a debris disk. All previously known dusty white dwarfs are of the DAZ/DBZ spectral type due to accretion of metals from the disk. High-resolution optical spectroscopy is needed to search for metal absorption lines in PG1541 and to constrain the accretion rate from the disk. PG1541 is only 55 pc away from the Sun and the discovery of its disk in our survey demonstrates that our knowledge of the nearby dusty white dwarf population is far from complete.