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In the line-of-sight toward the DO-type white dwarf RX J0503.9-2854, the density of the interstellar medium (ISM) is very low, and thus the contamination of the stellar spectrum almost negligible. This allows us to identify many metal lines in a wide wavelength range from the extreme ultraviolet to the near infrared. In previous spectral analyses, many metal lines in the ultraviolet spectrum of RX J0503.9-2854 have been identified. A complete line list of observed and identified lines is presented here. We compared synthetic spectra that had been calculated from model atmospheres in non-local thermodynamical equilibrium, with observations. In total, we identified 1272 lines (279 of them were newly assigned) in the wavelength range from the extreme ultraviolet to the near infrared. 287 lines remain unidentified. A close inspection of the EUV shows that still no good fit to the observed shape of the stellar continuum flux can be achieved although He, C, N, O, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Mn, Fe, Cr, Ni Zn, Ga, Ge, As, Kr, Zr, Mo, Sn, Xe, and Ba are included in the stellar atmosphere models. There are two possible reasons for the deviation between observed and synthetic flux in the EUV. Opacities from hitherto unconsidered elements in the model-atmosphere calculation may be missing and/or the effective temperature is slightly lower than previously determined.
There is a striking paucity of hydrogen-rich (DA) white dwarfs (WDs) relative to their hydrogen-deficient (non-DA) counterparts at the very hot end of the WD cooling sequence. The three hottest known DAs (surface gravity log g $geq$ 7.0) have effecti
We present the mass distribution for all S/N > 15 pure DA white dwarfs detected in the Sloan Digital Sky Survey up to Data Release 12, fitted with Koester models for ML2/alpha=0.8, and with Teff > 10 000 K, and for DBs with S/N >10, fitted with ML2/a
As they evolve, white dwarfs undergo major changes in surface composition, a phenomenon known as spectral evolution. In particular, some stars enter the cooling sequence with helium atmospheres (type DO) but eventually develop hydrogen atmospheres (t
We revisit the properties and astrophysical implications of the field white dwarf mass distribution in preparation of Gaia applications. Our study is based on the two samples with the best established completeness and most precise atmospheric paramet
The metal abundances in the atmospheres of hot white dwarfs (WDs) entering the cooling sequence are determined by the preceding Asymptotic Giant Branch (AGB) evolutionary phase and, subsequently, by the onset of gravitational settling and radiative l