J/A+A/686/A29 Spectra of 3 PN with [WC] central star (Werner+, 2024)
Spectroscopic survey of faint planetary-nebula nuclei.
III. A [WC] central star and two new PG1159 nuclei.
Werner K., Todt H., Bond H.E., Zeimann G.R.
<Astron. Astrophys. 686, A29 (2024)>
=2024A&A...686A..29W 2024A&A...686A..29W (SIMBAD/NED BibCode)
ADC_Keywords: Planetary nebulae ; Stars, white dwarf ; Spectra, optical
Keywords: stars: atmospheres - stars: evolution - white dwarfs -
planetary nebulae: individual: Abell 25 -
planetary nebulae: individual: StDr 138 -
planetary nebulae: individual: RaMul 2
Abstract:
We present spectroscopy of three hydrogen-deficient central stars of
faint planetary nebulae, with effective temperatures (Teff) in excess
of 100000K. The nucleus of RaMul 2 is a Population II Wolf-Rayet
star of spectral type [WC], and the central stars of Abell 25 and StDr
138 are two new members of the PG1159 class. Our spectral analyses
reveal that their atmospheres have a similar chemical composition.
They are dominated by helium and carbon, which was probably caused by
a late helium-shell flash. Coincidentally, the three stars have
similar masses of about M=0.53M☉ and, hence, form a post-AGB
evolutionary sequence of an initially early-K type main-sequence star
with M=0.8M☉. The central stars cover the period during which the
luminosity fades from about 3000 to 250L☉ and the radius shrinks
from about 0.15 to 0.03R☉. The concurrent increase of the surface
gravity during this interval from logg=5.8 to 7.2 causes the
shutdown of the stellar wind from an initial mass-loss rate of
log(dM/dt)/(M☉/yr)=-6.4, as measured for the [WC] star. Along the
contraction phase, we observe an increase of Teff from 112000K,
marked by the [WC] star, to the maximum value of 140000K and a
subsequent cooling to 130000K, marked by the two PG1159 stars.
Description:
Spectroscopic observations were made with the LRS2 spectrograph on the
HET at McDonald Observatory on 2019-11-01, 2021-02-07 and 2021-11-30
for Abell 25, 2021-11-02 for StDr 138 and 2023-03-31 for RaMul 2.
Objects:
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RA (2000) DE Designation(s)
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08 06 46.501 -02 52 35.18 Abell 25 = Gaia DR3 3070613063558890240
03 37 55.777 +43 44 15.74 StDr 138 = Gaia DR3 238382646416730368
19 49 53.705 +18 40 14.82 RaMul 2 = Gaia DR3 1821559921653783552
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
abell25.dat 19 4716 Abell 25 HET/LSR2 spectrum (fig. 1)
stdr138.dat 19 4715 Stdr 138 HET/LSR2 spectrum (fig. 2)
ramul2.dat 19 4716 Ra-Mul 2 HET/LSR2 spectrum (fig. 3)
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Byte-by-byte Description of file: abell25.dat stdr138.dat ramul2.dat
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Bytes Format Units Label Explanations
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1- 6 F6.1 0.1nm lambda Wavelength in Angstroem
10- 19 F10.7 --- RFlux Relative flux
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Acknowledgements:
Klaus Werner, werner(at)astro.uni-tuebingen.de
(End) Patricia Vannier [CDS] 01-Mar-2024