The Elemental Abundances in Bare Planetary Nebula Central Stars and the Shell Burning in AGB Stars

Werner, K.; Herwig, Falk

doi:10.1086/500443

Cited by 328 publications

(494 citation statements)

References 113 publications

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“…The abundances (Tab. 1) are in agreement with expectations of evolutionary models (Werner & Herwig 2006). The inclusion of iron-group opacities and the availability of high resolution FUSE data lead to the revised values of T eff and log g. The change in T eff is comparable to the uncertainties, but the decrease in log g is significant.…”

Section: Observations and Analysissupporting

confidence: 84%

Spectral analysis of PG 1034+001, the exciting star of Hewett 1

Mahsereci¹,

Ringat²,

Rauch³

et al. 2011

Proc. IAU

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Abstract. PG 1034+001 is an extremely hot, helium-rich DO-type star that excites the planetary nebula Hewett 1 and large parts of the surrounding interstellar medium. We present preliminary results of an ongoing spectral analysis by means of non-LTE model atmospheres that consider most elements from hydrogen to nickel. This analysis is based on high-resolution ultraviolet (FUSE, IUE) and optical (VLT/UVES, Keck) data. The results are compared with those of PG 1034+001's spectroscopic twin, the DO star PG 0038+199.

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Section: Observations and Analysissupporting

confidence: 84%

Spectral analysis of PG 1034+001, the exciting star of Hewett 1

Mahsereci¹,

Ringat²,

Rauch³

et al. 2011

Proc. IAU

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“…The seven new PG 1159 stars add to the forty objects found so far (Werner & Herwig 2006). The new four O(He) stars double the number of such stars known (Reindl et al 2014).…”

Section: Observations and Line Identificationsmentioning

confidence: 68%

“…The hybrids are thought to be created by a particular variant of late He-shell flashes, the AGB final thermal puls (AFTP) scenario. Only four such objects were hitherto known, all of them being cooler (96 000-130 000 K; see Werner & Herwig 2006, and references therein). The surface gravity of SDSS 1521 is rather low (log g = 6) but not unusual, as the other four hybrids known have log g = 6.8-5.7.…”

Section: Pg 1159 Starsmentioning

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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“…In the last decade, emphasize was laid on the analysis of H-poor post-AGB stars (cf. Werner & Herwig 2006) although the majority (≈ 75 %) of all post-AGB stars is H-rich. Only a few systematic analyses are available in the literature concerning metal abundances of H-rich CSPNe.…”

Section: Introductionmentioning

confidence: 99%