Hard X-ray emission associated with white dwarfs. II

Research output: Contribution to journalArticle

Abstract

We have previously conducted a search for X-ray sources coincident with white dwarfs using the white dwarf catalog compiled by McCook & Sion and the ROSAT sources in the WGA Catalog (Paper I). To include the white dwarfs discovered since 1999 and to include the X-ray sources detected in ROSAT Position Sensitive Proportional Counter (PSPC) observations made with a boron filter, we have carried out another search using an updated list of white dwarfs and the final catalogs of the ROSAT PSPC observations with and without a boron filter. Forty-seven new X-ray sources convincingly coincident with white dwarfs are found and reported in this paper. Among these, only five show hard X-ray emission: three possess confirmed or suggested late-type companions, one is apparently single, and the other is likely a misclassified BL Lac object. The apparently single white dwarf with hard X-ray emission, KPD 0005+5106, was discussed extensively in Paper I. Photospheric origin for the hard X-ray emission from hot DO and DQZO white dwarfs remains a tantalizing possibility, but high-quality near-IR spectroscopic observations and monitoring of the Ha emission line are needed to rule out the existence of a faint dMe companion.

Original languageEnglish (US)
Pages (from-to)477-480
Number of pages4
JournalAstronomical Journal
Volume127
Issue number1 1777
StatePublished - Jan 2004

Keywords

  • Binaries: general
  • Stars: coronae
  • Stars: late-type
  • White dwarfs
  • X-rays

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

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