The discovery of a debris disc around the DAV white dwarf PG 1541+651

Abstract

Abstract To search for circumstellar discs 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 disc 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 and photometric observations with the warm Spitzer Space Telescope confirm the presence of a warm debris disc within 0.13–0.36 R⊙ (11–32 × the stellar radius) at an inclination angle of 60°. At Teff = 11 880 K, PG1541 is almost a twin of the DAV white dwarf G29-38, which also hosts a debris disc. All previously known dusty white dwarfs are of the DAZ/DBZ spectral type due to accretion of metals from the disc. High-resolution optical spectroscopy is needed to search for metal absorption lines in PG1541 and to constrain the accretion rate from the disc. PG1541 is only 55 pc away from the Sun and the discovery of its disc in our survey demonstrates that our knowledge of the nearby dusty white dwarf population is far from complete.