Pith. sign in

REVIEW 1 cited by

Not yet reviewed by Pith; the record is open.

This paper has not been read by Pith yet. Machine review is queued; the pith claim, tier, and objections will appear here once it completes.

SPECIMEN: schema-true, not a live event

T0 review · schema-true

One-sentence machine reading of the paper's core claim.

pith:XXXXXXXX · record.json · timestamp

arxiv 1807.11707 v1 pith:PQXRGM6H submitted 2018-07-31 astro-ph.SR

The hot white dwarf in the peculiar binary nucleus of the planetary nebula EGB6

classification astro-ph.SR
keywords foundnucleusstarabundancearoundcompactdiskdwarf
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved
0 comments
read the original abstract

EGB6 is an extended, faint old planetary nebula (PN) with an enigmatic nucleus. The central star (PG0950+139) is a hot DAOZ-type white dwarf (WD). An unresolved, compact emission knot was discovered to be located 0.166" away from the WD and it was shown to be centered around a dust-enshrouded low-luminosity star. It was argued that the dust disk and evaporated gas (photoionized by the hot WD) around the companion are remnants of a disk formed by wind material captured from the WD progenitor when it was an asymptotic giant branch (AGB) star. In this paper, we assess the hot WD to determine its atmospheric and stellar parameters. We performed a model-atmosphere analysis of ultraviolet (UV) and optical spectra. We found Teff = 105,000 +/- 5000 K, log g = 7.4 +/- 0.4, and a solar helium abundance (He = 0.25 +/- 0.1, mass fraction). We measured the abundances of ten more species (C, N, O, F, Si, P, S, Ar, Fe, Ni) and found essentially solar abundance values, indicating that radiation-driven wind mass-loss, with a theoretical rate of log(dot-M/M_sun/yr) = -11.0 (+1.1)(-0.8) prevents the gravitational separation of elements in the photosphere. The WD has a mass of M/M_sun = 0.58 (+0.12)(-0.04) and its post-AGB age (log(t_evol/yr) = 3.60 (+1.26)(-0.09)) is compatible with the PN kinematical age of log(t_PN}/yr) = 4.2. In addition, we examined the UV spectrum of the hot nucleus of a similar object with a compact emission region, TOL26 (PN G298.0+34.8), and found that it is a slightly cooler DAOZ WD (Teff about 85,000 K), but this WD shows signatures of gravitational settling of heavy elements.

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Forward citations

Cited by 1 Pith paper

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. Studying hot evolved stars with ultraviolet spectroscopy

    astro-ph.IM 2026-06 unverdicted novelty 2.0

    Review of UV spectroscopy applications to hot evolved stars, emphasizing HST contributions and the need for continued observations ahead of HWO.