Far-ultraviolet space telescope imaging spectrograph spectra of the white dwarf REJ 1032+532. II. Stellar spectrum

J. B. Holberg, M. A. Barstow, F. C. Bruhweiler, Ivan - Hubeny, E. M. Green

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

We discuss the Hubble Space Telescope Space Telescope Imaging Spectrograph UV echelle spectrum of the hot DA white dwarf REJ 1032+532. The interstellar data from this spectrum are presented by Holberg and coworkers. In this paper we discuss a number of strong photospheric features due to C, N, and Si that are present in the REJ 1032+532 spectrum. While the inferred heavy element content of REJ 1032+532 roughly matches the predictions of radiative levitation for carbon and silicon, the observed nitrogen abundance greatly exceeds predictions by a factor of 50. The observed shapes of the N v lines provide the first evidence, at UV wavelengths, of heavy element stratification in a hot DA white dwarf. Homogeneous models are unable to reproduce the shape of the REJ 1032+532 N v lines, nor can they account for the relatively low degree of EUV opacity in the star. We present a simple stratified nitrogen model that resolves these problems. The high degree of stratification in REJ 1032+532 is the signature of ongoing mass loss in this star. The radial velocity of REJ 1032+532 obtained with Space Telescope Imaging Spectrograph differs by 44 km s-1 from that obtained from the Balmer H I lines with the Multiple Mirror Telescope. This suggests that REJ 1032+532 is likely a member of a binary system containing either a late M star or another white dwarf.

Original languageEnglish (US)
Pages (from-to)850-858
Number of pages9
JournalAstrophysical Journal
Volume517
Issue number2 PART 1
StatePublished - Jun 1 1999
Externally publishedYes

Fingerprint

stellar spectra
spectrographs
telescopes
heavy elements
stratification
late stars
nitrogen
stars
M stars
levitation
prediction
predictions
opacity
Hubble Space Telescope
radial velocity
silicon
signatures
mirrors
wavelength
carbon

Keywords

  • Stars: abundances
  • Ultraviolet: stars
  • White dwarfs

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Holberg, J. B., Barstow, M. A., Bruhweiler, F. C., Hubeny, I. ., & Green, E. M. (1999). Far-ultraviolet space telescope imaging spectrograph spectra of the white dwarf REJ 1032+532. II. Stellar spectrum. Astrophysical Journal, 517(2 PART 1), 850-858.

Far-ultraviolet space telescope imaging spectrograph spectra of the white dwarf REJ 1032+532. II. Stellar spectrum. / Holberg, J. B.; Barstow, M. A.; Bruhweiler, F. C.; Hubeny, Ivan -; Green, E. M.

In: Astrophysical Journal, Vol. 517, No. 2 PART 1, 01.06.1999, p. 850-858.

Research output: Contribution to journalArticle

Holberg, JB, Barstow, MA, Bruhweiler, FC, Hubeny, I & Green, EM 1999, 'Far-ultraviolet space telescope imaging spectrograph spectra of the white dwarf REJ 1032+532. II. Stellar spectrum', Astrophysical Journal, vol. 517, no. 2 PART 1, pp. 850-858.
Holberg, J. B. ; Barstow, M. A. ; Bruhweiler, F. C. ; Hubeny, Ivan - ; Green, E. M. / Far-ultraviolet space telescope imaging spectrograph spectra of the white dwarf REJ 1032+532. II. Stellar spectrum. In: Astrophysical Journal. 1999 ; Vol. 517, No. 2 PART 1. pp. 850-858.
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