J/A+A/686/A29ivo://CDS.VizieR/J/A+A/686/A29doi:10.26093/cds/vizier.36860029CDSWerner K.Todt H.Bond H.E.Zeimann G.R.2024-11-21T20:01:13Z2024-05-28T10:55:27ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frplanetary-nebulaewhite-dwarf-starsvisible-astronomyspectroscopyWe 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_{sun}_ and, hence, form a post-AGB evolutionary sequence of an initially early-K type main-sequence star with M=0.8M_{sun}_. The central stars cover the period during which the luminosity fades from about 3000 to 250L_{sun}_ and the radius shrinks from about 0.15 to 0.03R_{sun}_. 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_{sun}_/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.2024A&A...686A..29Whttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/686/A29CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/686/A29https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/686/A29http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/686/A29https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/686/A29https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/686/A29http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/686/A29GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/686/A29/abell25Abell 25 HET/LSR2 spectrum (fig. 1)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength in Angstroem0.1nmem.wlfloatRFluxRelative fluxphot.flux;arith.ratiodoubleJ/A+A/686/A29/stdr138Stdr 138 HET/LSR2 spectrum (fig. 2)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength in Angstroem0.1nmem.wlfloatRFluxRelative fluxphot.flux;arith.ratiodoubleJ/A+A/686/A29/ramul2Ra-Mul 2 HET/LSR2 spectrum (fig. 3)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength in Angstroem0.1nmem.wlfloatRFluxRelative fluxphot.flux;arith.ratiodouble