Spectral analyses of DO white dwarfs and PG 1159 stars from the Sloan Digital Sky Survey

Hügelmeyer, S. D.; Werner, K.; Krzesiński, Jurek; Nitta, A.; Kleinman, S. J.

doi:10.1051/0004-6361:20053280

Cited by 14 publications

(24 citation statements)

References 26 publications

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“…4. As already mentioned in Hügelmeyer et al (2005), DOs from the SDSS seem to have higher masses than those analysed before the SDSS. We assume that this is an effect introduced by the application of our automated fitting routines which favour good line wing fits, thus steering the fits towards higher surface gravities.…”

Section: Do White Dwarfssupporting

confidence: 55%

“…We present results from this work and Hügelmeyer et al (2005) together in Tables 1 and 2. Some atmospheric parameters for the PG 1159 stars analysed in Hügelmeyer et al (2005) have changed after applying our χ 2 -fitting routines to these objects.…”

Section: Resultsmentioning

confidence: 99%

“…Positions of the PG 1159 stars (black diamonds) analysed in this paper compared to evolutionary tracks from Blöcker (1995) and Schönberner (1983) (dashed lines), and Wood & Faulkner (1986) (solid lines). The sdO star from this work (black asterisk) and the one from Hügelmeyer et al (2005) are plotted together with tracks from Dorman et al (1993) ; 3 dent in spectrum at ∼5800 Å.…”

Section: Do White Dwarfsmentioning

confidence: 99%

“…Our fitting routines found a best-fit model with T eff = 55 000 K for the DO part of SDSS J091621.83+052119.2 Wood (1995). The triangles represent the 27 hitherto known DOs (see Dreizler et al 1997;Werner et al 2004;Hügelmeyer et al 2005). using the normalised spectrum.…”

Section: Combined Do and M Dwarf Spectramentioning

confidence: 99%

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Spectral analyses of eighteen hot H-deficient (pre-) white dwarfs from the Sloan Digital Sky Survey Data Release 4

Hügelmeyer¹,

Homeier²,

Krzesiński

et al. 2006

A&A

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Context. The Sloan Digital Sky Survey Data Release 4 has provided spectra of several new PG 1159 stars and DO white dwarfs. This increase in known hot H-deficient compact objects significantly improves the statistics and helps to investigate late stages of stellar evolution. Aims. From the optical SDSS spectra, effective temperatures and surface gravities are derived in order to place the observed objects in an evolutionary context. Especially the connection between PG 1159 stars and DO white dwarfs shall be investigated. Methods. Using our non-LTE model atmospheres and applying χ 2 -fitting techniques, we determine stellar parameters and their errors. We derive total stellar masses for the DO white dwarfs using model evolutionary tracks. Results. We confirm three PG 1159 stars, with one showing ultra-high excitation ion features, and one sdO which we originally classified as a PG 1159 star. Additionally, we re-analysed the known PG 1159 star, PG 1424+535, with our new models. Furthermore, we present the first spectral analyses of thirteen DO white dwarfs, three of which show M-star features in their spectra, while two display ultra-high excitation ion features.

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Section: Do White Dwarfssupporting

confidence: 55%

Section: Resultsmentioning

confidence: 99%

Section: Do White Dwarfsmentioning

confidence: 99%

Section: Combined Do and M Dwarf Spectramentioning

confidence: 99%

See 2 more Smart Citations

Spectral analyses of eighteen hot H-deficient (pre-) white dwarfs from the Sloan Digital Sky Survey Data Release 4

Hügelmeyer¹,

Homeier²,

Krzesiński

et al. 2006

A&A

Self Cite

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show abstract

“…In the Data Release (DR) 4 of the Sloan Digital Sky Survey (SDSS), Hügelmeyer et al (2005Hügelmeyer et al ( , 2006) discovered many new PG 1159 stars and DOs and performed spectral analyses. Here we present a similar study for the DR 10.…”

Section: Introductionmentioning

confidence: 99%

New hydrogen-deficient (pre-) white dwarfs in the Sloan Digital Sky Survey Data Release 10

Werner¹,

Rauch²,

Kepler

2014

A&A

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We have detected 21 new, very hot hydrogen-deficient (pre-) white dwarfs (spectral types O(He), hot DO, PG1159) in the Data Release 10 of the Sloan Digital Sky Survey. We present the results of non-local thermodynamic equilibrium (non-LTE) model-atmosphere analyses. The seven PG1159 stars have effective temperatures and surface gravities in the ranges T eff = 100 000-140 000 K and log g = 6-7.5. The hottest one is a new member of the rare hybrid-PG1159 subtype, indicating the presence of residual hydrogen. The ten new hot DOs span T eff = 65 000-120 000 K and log g = 7.5-8. Carbon abundances were derived and it is found that the PG1159 star values (C/He = 0.33-0.03 by number) and the DO values (<0.0004-0.01) cover distinct but adjacent ranges. With the discovery of four new O(He) stars (T eff = 80 000-100 000 K, log g = 5-5.5, C/He = 0.002-0.01), we double the number of known members of this rare spectral class. One of them is particularly interesting because it is unusually rich in C, N, O, and Si. Unexpected problems arose with the DOs because many He ii lines of every other star are so deep that they cannot be matched by any model. This is most conspicuous in the case of one object which exhibits the occurrence of ultrahigh-ionization metal features, a hitherto unexplained phenomenon that is known from a disquieting large fraction of hot DOs.

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Hot White Dwarfs

Sion

2011

White Dwarf Atmospheres and Circumstellar Environments

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The article covers the physical properties and evolution of single white dwarfs ranging in temperature from 20,000K to 200,000 and higher, the hottest know electron-degenerate stars. After discussing the classification of their spectra, the author reviews the known properties, parameters, evolutionary state, as well as persisting and new puzzles regarding all spectroscopic subclasses of Hot White Dwarfs: the hot DA white dwarfs, the DAO white dwarfs, the PG1159 degenerates, the DO white dwarfs, the DB white dwarfs, the DBA white dwarfs, and the Hot DQ white dwarfs (an entirely new class). The most recent observational and theoretical advances are brought to bear on the topic.The spectroscopic properties of white dwarfs are determined by a host of physical processes which control and/or modify the flow of elements and, hence, surface abundances in high gravity atmospheres: convective dredge-up, mixing and dilution, accretion of gas and dust from the interstellar medium and debris disks, gravitational and thermal diffusion, radiative forces, mass loss due to wind outflow and episodic mass ejection, late nuclear shell burning and late thermal pulses, rotation, magnetic fields, and possible composition relics of prior pre-white dwarf evolutionary states. Virtually all of these processes and factors may operate in hot white dwarfs, leading to the wide variety of observed spectroscopic phenomena and spectral evolution.The basic thrust of research on hot white dwarfs is three-fold: (1) to elucidate the evolutionary links between the white dwarfs and their pre-white dwarf progenitors, whether from the asymptotic giant branch (AGB), the extended horizontal branch, stellar mergers, or binary evolution; (2) to understand the physics of the different envelope processes operating in hot white dwarfs as they cool; and (3) to disentangle and elucidate the relationships between the different spectroscopic subclasses and hybrid subclasses of hot white dwarfs as spectral evolution proceeds. This includes the source of photospheric metals, the chemical species observed, and the measured surface abundances in hot degenerates. The evolutionary significance of certain observed ion species is complicated by the role of radiative forces and weak winds in levitating and ejecting elements at temperatures >20,000 K.

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Spectral analyses of DO white dwarfs and PG 1159 stars from the Sloan Digital Sky Survey

Cited by 14 publications

References 26 publications

Spectral analyses of eighteen hot H-deficient (pre-) white dwarfs from the Sloan Digital Sky Survey Data Release 4

Spectral analyses of eighteen hot H-deficient (pre-) white dwarfs from the Sloan Digital Sky Survey Data Release 4

New hydrogen-deficient (pre-) white dwarfs in the Sloan Digital Sky Survey Data Release 10

Hot White Dwarfs

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