The constitution of the atmospheric layers and the extreme ultraviolet spectrum of hot hydrogen-rich white dwarfs

Abstract

view Abstract Citations (49) References (52) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Constitution of the Atmospheric Layers and the Extreme Ultraviolet Spectrum of Hot Hydrogen-rich White Dwarfs Vennes, Stephane Abstract An analysis is presented of the atmospheric properties of hot, H-rich, DA white dwarfs that is based on optical, UV, and X-ray observations aimed at predicting detailed spectral properties of these stars in the range 80-800 A. The divergences between observations from a sample of 15 hot DA white dwarfs emitting in the EUV/soft X-ray range and pure H synthetic spectra calculated from a grid of model atmospheres characterized by Teff and g are examined. Seven out of 15 DA stars are found to consistently exhibit pure hydrogen atmospheres, the remaining seven stars showing inconsistency between FUV and EUV/soft X-ray data that can be explained by the presence of trace EUV/soft X-ray absorbers. Synthetic data are computed assuming two other possible chemical structures: photospheric traces of radiatively levitated heavy elements and a stratified hydrogen/helium distribution. Predictions about forthcoming medium-resolution observations of the EUV spectrum of selected hot H-rich white dwarfs are made. Publication: The Astrophysical Journal Pub Date: May 1992 DOI: 10.1086/171310 Bibcode: 1992ApJ...390..590V Keywords: Extreme Ultraviolet Radiation; Hot Stars; Stellar Atmospheres; Stellar Spectra; White Dwarf Stars; X Ray Stars; Atmospheric Stratification; Ultraviolet Astronomy; Ultraviolet Spectra; X Ray Astronomy; X Ray Spectra; Astrophysics; STARS: ATMOSPHERES; ULTRAVIOLET: STARS; STARS: WHITE DWARFS; X-RAYS: STARS full text sources ADS | data products SIMBAD (15) MAST (1) INES (1)