J/ApJ/931/157ivo://CDS.VizieR/J/ApJ/931/157doi:10.26093/cds/vizier.19310157CDSAadland E.Massey P.John Hillier D.Morrell N.I.Neugent K.F.,Eldridge J.J.2024-11-06T20:25:46Z2024-05-17T13:27:26ZCDS support team

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

cds-question@unistra.frspectroscopyultraviolet-astronomyvisible-astronomyinfrared-astronomywolf-rayet-starsabsolute-magnitudestellar-spectral-typesmagellanic-cloudsAre WO-type Wolf-Rayet (WR) stars in the final stage of massive star evolution before core-collapse? Although WC- and WO-type WRs have very similar spectra, WOs show a much stronger OVI{lambda}{lambda}3811,34 emission-line feature. This has usually been interpreted to mean that WOs are more oxygen rich than WCs, and thus further evolved. However, previous studies have failed to model this line, leaving the relative abundances uncertain, and the relationship between the two types unresolved. To answer this fundamental question, we modeled six WCs and two WOs in the LMC using UV, optical, and NIR spectra with the radiative transfer code cmfgen in order to determine their physical properties. We find that WOs are not richer in oxygen; rather, the OVI feature is insensitive to the abundance. However, the WOs have a significantly higher carbon and lower helium content than the WCs, and hence are further evolved. A comparison of our results with single-star Geneva and binary BPASS evolutionary models show that, while many properties match, there is more carbon and less oxygen in the WOs than either set of evolutionary model predicts. This discrepancy may be due to the large uncertainty in the ^12^C+^4^He->^16^O nuclear reaction rate; we show that if the Kunz+ 2002ApJ...567..643K rate is decreased by a factor of 25%-50%, then there would be a good match with the observations. It would also help explain the LIGO/VIRGO detection of black holes whose masses are in the theoretical upper mass gap.2022ApJ...931..157Ahttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/931/157CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toIII/136 : Optical spectrophotometry of WR C and O Stars (Torres+ 1987)III/215 : 7th Catalog of Galactic Wolf-Rayet stars (van der Hucht, 2001)J/AJ/119/2214 : Photometry of Magellanic OB associations (Massey+, 2000)J/ApJ/611/452 : Evolution of massive stars (El Eid+, 2004)J/A+A/537/A146 : Stellar models with rot. 0.8<M<120, Z=0.014 (Ekstrom+, 2012)J/ApJ/748/96 : Massive binaries in the LMC (Massey+, 2012)J/ApJ/863/181 : The fifth catalog of LMC Wolf-Rayet stars (Neugent+, 2018)J/AJ/158/192 : HeII em. from Wolf-Rayet stars in MW & LMC (Leitherer+, 2019)J/ApJ/888/54 : Sp. of a rare low-mass Wolf-Rayet star in LMC (Margon+, 2020)J/ApJ/898/85 : CII emission-line stars in LMC with MagE sp. (Margon+, 2020)J/ApJ/922/177 : 2MASS red supergiants in the SMC (Massey+, 2021)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/931/157https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/931/157http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/931/157https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/931/157https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/931/157http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/931/157GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/931/157/sample (*Our (including data from the first paper: Aadland+ 2022ApJ...924...44A --added here by CDS))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/931/157/sample?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/931/157/sample?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/931/157/sample?GETtext/xml+votable180.050000true83.5801667-69.75286110.0055555555555555566/33076 33091 33094-33095 33098 33112 33122 33126https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/931/157?format=asciiUVOpticalInfrareddefaultJ/ApJ/931/157/sample*Our (including data from the first paper: Aadland+ 2022ApJ...924...44A --added here by CDS)SimbadNameSimbad column added by the CDSmeta.idcharnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar namemeta.id;meta.maincharSpTSpectral typesrc.spTypecharf_SpTFlag on SpT (1)meta.codecharRAJ2000Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of declination (J2000)pos.eq.dec;meta.mainVmag[12.6/15.2] V magnitudemagphot.mag;em.opt.VfloatVMag[-6/-3.8] Absolute V magnitude, M_V_ (2)magphys.magAbs;em.opt.VfloatANameAlternative IDs (for objects from this paper)meta.idcharRefReference paper; column added by CDS (3)meta.bibcharspInteractive spectrum plotmeta.ref.urlchar