2008A&A...492L..43W


C.D.S. - SIMBAD4 rel 1.7 - 2019.11.17CET12:30:24

2008A&A...492L..43W - Astronomy and Astrophysics, volume 492, L43-47 (2008/12-4)

Discovery of photospheric CaX emission lines in the far-UV spectrum of the hottest known white dwarf (KPD0005+5106).

WERNER K., RAUCH T. and KRUK J.W.

Abstract (from CDS):

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≃200000K) DO white dwarf KPD0005+5106 and they stem from extremely highly ionized calcium (CaX λλ 1137, 1159Å). Their photospheric origin is confirmed by non-LTE line-formation calculations. This is the highest ionisation stage of any element ever observed in a stellar photosphere. Calcium has never been detected before in any hot white dwarf or central star of planetary nebula. The calcium abundance determination for KPD0005+5106 (1-10 times solar) is difficult, because the line strengths are rather sensitive to current uncertainties in the knowledge of effective temperature and surface gravity. We discuss the possibility that the calcium abundance is much lower than expected from diffusion/levitation equilibrium theory. The same emission lines are exhibited by the [WCE]-type central star NGC2371. Another CaX line pair (λλ 1461, 1504Å) is probably present in a Hubble Space Telescope spectrum of the PG1159-type central star NGC246.

Abstract Copyright:

Journal keyword(s): stars: abundances - stars: atmospheres - stars: evolution - stars: AGB and post-AGB - stars: white dwarfs

Simbad objects: 9

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Number of rows : 9

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 KPD 0005+5106 WD* 00 08 18.1706793307 +51 23 16.594540226 11.80 13.04 13.32 13.53   DOZ1 113 0
2 NGC 246 PN 00 47 03.3420803259 -11 52 18.975106178 10.15 11.52 11.76 12.18   PG1159 448 0
3 NGC 2371 PN 07 25 34.6884571396 +29 29 26.430027683   14.48 13.5     Oe 347 0
4 PN Lo 4 PN 10 05 45.7878014012 -44 21 33.523563573           sdO 124 1
5 PG 1144+005 WD* 11 46 35.2287794057 +00 12 33.539708785   14.59 14.9     PG1159 78 0
6 PG 1501+664 WD* 15 02 09.6296551839 +66 12 19.146114550   16.07 16.37     DZQ1 148 0
7 PG 1520+525 PN 15 21 46.5638122905 +52 22 03.868713843   15.56 16.6     PG1159 96 1
8 PN K 1-16 PN 18 21 52.1081781582 +64 21 53.413814961   14.44 14.96 15.26   PG1159 229 0
9 MWP 1 PN 21 17 08.2817539788 +34 12 27.415871206     12.33     PG1159 172 0

    Equat.    Gal    SGal    Ecl

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2019.11.17-12:30:24

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