HubbleSpace Telescope ultraviolet spectroscopy of the hottest known helium-rich pre-white dwarf KPD 0005+5106
نویسندگان
چکیده
منابع مشابه
Telescope Far Ultraviolet Spectroscopy of the Dwarf Nova
We obtained three consecutive HST spectroscopic observations of a single superoutburst of the dwarf nova VW Hydri. The spectra cover the beginning, middle, and end of the superoutburst. All of the spectra are dominated by strong absorption lines due to CIII (1175 Å), Lyman alpha (1216 Å), NIV (1238 Å, 1242 Å), SII (1260-65 Å), SIII (1300 Å), CII (1335 Å), SIV (1394 Å, 1402 Å) and CIV (1548 Å, 1...
متن کاملHubble Space Telescope spectroscopy of hot helium–rich white dwarfs: metal abundances along the cooling sequence
Metal abundances are the indicators of the chemical evolution in white dwarfs, which is dominated by the element separation due to the strong gravitational field. A reliable analysis and interpretation requires high resolution and high signalto-noise UV spectroscopy. For hot helium rich DO white dwarfs this is currently only feasible with the Hubble Space Telescope. In this paper I report on ou...
متن کاملDiscovery of photospheric Ca X emission lines in the far - UV spectrum of the hottest known white dwarf ( KPD 0005 + 5106 ) ⋆
For the first time, we have identified photospheric emission lines in the far-UV spectrum of a white dwarf. They were discovered in the Far Ultraviolet Spectroscopic Explorer spectrum of the hot (Teff ≈ 200 000 K) DO white dwarf KPD 0005+5106 and they stem from extremely highly ionized calcium (Ca X λλ 1137, 1159 Å). Their photospheric origin is confirmed by non-LTE line-formation calculations....
متن کاملThe Rotational Velocity of Helium-rich Pre-White Dwarfs
Previous investigations on hydrogen-rich white dwarfs generally yield only very small rotational velocities (vrot · sin i). We have analyzed line profiles in high-resolution optical spectra of eight hydrogen-deficient (pre-) white dwarfs and find deviations from the dominant Stark line broadening in five cases which, interpreted as an effect of stellar rotation, indicate projected rotational ve...
متن کاملOn the Dissociation Equilibrium of H2 in Very Cool, Helium-Rich White Dwarf Atmospheres
We investigate the dissociation equilibrium of H2 in very cool, helium-rich white dwarf atmospheres. We present the solution of the non-ideal chemical equilibrium for the dissociation of molecular hydrogen in a medium of dense helium. We find that at the photosphere of cool white dwarfs of Teff = 4000K, the non-ideality results in an increase of the mole fraction of molecular hydrogen by up to ...
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ژورنال
عنوان ژورنال: Astronomy & Astrophysics
سال: 2015
ISSN: 0004-6361,1432-0746
DOI: 10.1051/0004-6361/201527212