J/A+A/711/A151ivo://CDS.VizieR/J/A+A/711/A151CDSSimon-Diaz S.Holgado G.Martinez-Sebastian C.Carretero-Castrillo M.,Jin H.Urbaneja M.A.Gamen R.Puls J.de Burgos A.Garcia M.,Herrero A.Keszthelyi Z.Langer N.Najarro F.Paredes J.M.Ribo M.2026-07-10T07:34:36Z2026-07-10T08:33:49ZCDS support team

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

cds-question@unistra.frmilky-way-galaxyo-starsmultiple-starschemical-abundancesvisible-astronomyeffective-temperatureThe presence of massive O-type stars with surfaces enriched by CNO-cycle products has been known since the early 1980s. For many years, internal rotational mixing was assumed to be the dominant mechanism responsible for this chemical contamination. However, accumulating evidence suggests that binary interaction may play an equally important, if not dominant, role. We aim to carry out a large-scale investigation of surface helium (He) abundances in Galactic O-type stars, based on the results from the analysis of high-quality spectroscopic data from the IACOB project. We perform a homogeneous spectroscopic analysis of 318 Galactic O-type stars with the iacob-broad and fastwind/iacob-gbat tools, deriving rotational velocities, atmospheric parameters, and He abundances. We also account for the influence of binarity, and parameter degeneracies on the abundance determinations. We present homogeneously determined surface He abundances (YHe=N(He)/N(H)) for the so far largest, statistically significant sample of Galactic O-type stars. About 60% of the stars show He abundances consistent with the cosmic abundance standard of YHe=0.098+/-0.002. For another 18% of the stars, we obtain anomalously low He abundance estimates, reaching values down to 0.07. These unusual He abundances might be a consequence of flux contamination of the analyzed spectra by a faint companion. The remaining 22% display clear He enrichment (YHe>0.13). We provide observational evidence indicating that most of these He-enriched stars are likely the products of binary interaction.Our study highlights how large spectroscopic surveys are gradually opening robust observational avenues to identify the products of massive binary interaction. It also emphasizes the need for caution when interpreting the spectroscopic properties of apparently single O-type stars. A significant fraction may in fact be the outcome of binary evolution rather than isolated stellar birth.2026A&A...711A.151Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/711/A151CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/711/A151https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/711/A151http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/711/A151https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/711/A151https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/711/A151http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/711/A151GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/711/A151/highhe (Results for the high He sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/711/A151/highhe?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/711/A151/highhe?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/711/A151/highhe?GETtext/xml+votable180.050000true14.059227861.76027080.005555555555555556Cone search capability for table J/A+A/711/A151/normhe (Results for the normal He sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/711/A151/normhe?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/711/A151/normhe?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/711/A151/normhe?GETtext/xml+votable180.050000true118.4091883-26.2340550.005555555555555556Cone search capability for table J/A+A/711/A151/lowhe (Results for the low He sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/711/A151/lowhe?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/711/A151/lowhe?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/711/A151/lowhe?GETtext/xml+votable180.050000true308.459862545.6613750.0055555555555555565/3661 6/1287 1293 1297 1299 1303 1332 1355 1558 1790 1946 2409 2899 3037 3051 3054 3214 3231 3245 3247 3249 3256-3257 3261 3263 3272 3301 3307 3315 3331 3337 3430 3585 3600 3622 3644 3649 3653 3724 5506 6891 12943 13255 13557 13999 14008 14179 14240 14253 14263 14283 14295 14353 14358-14359 14411 14456 14607 14623-14624 14630 14632-14633 14636 14643 14654-14655 14658 14689 14716 14737 14740-14741 14743 14745 14795 15369 15476 15478 15577 15631 15656 15663 15670 15672 15682-15683 15745 20613 21432 21531 21635 21638 21655-21656 22033 22088 22208 22211 22216 22240 22243 22249 22253 22854 22884 23637 23647 23717 23774 23962 23984 23996 24179 24555 28719 28796 28865 28890-28891 28895 28900 28913 28915 29036 29072 29089 29091 29095 29098 29101 29115 29158 29162 29461 29463 29467 29504 29512-29513 29515 29517 29530 29600 29866 30216 30221 30818 31748 37245 37333-37334 37339 37750 37833 37863 37870 37897 37899-37900 37907 37915 37923 37926 37930 37932 37934 37938 37948 38016 38018 38020 38022 38024 38026 38037 38074 39238 39248 39252 39264 39281 39374 39386 39775 39803-39804 39873 39876 39907 39931 39971 41103 41592 41598 41630 41652-41653 41668 41673 41675 41685-41686 41702 41715 41750 41769 41787 41813 41903 42171 42203 42206 42226 42228 42236 42283 42287 42303 42335 42383 42394 42398 42405 42417 42456 42458 42470-42471 42764 42768 43026 43030 43034 43041 43062 43144https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/711/A151?format=asciiOpticaldefaultJ/A+A/711/A151/highheResults for the high He samplerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStar-IDStar identifiermeta.id;meta.maincharSpClassSpectral classsrc.spTypecharvsiniProjected rotational velocitykm/sphys.veloc.rotatintvmacMacroturbulent velocitykm/sphys.velocintTeffEffective temperaturekKphys.temperature.effectivefloate_TeffUndertainty on TeffkKstat.error;phys.temperature.effectivefloatloggSurface gravitylog(cm.s**-2)phys.gravityfloatSimbadSimbad column added by the CDSmeta.ref.urlchare_loggUncertainty on logglog(cm.s**-2)stat.errorfloatlogLspSpectroscopic luminosityphys.luminosityfloate_logLspUncertainty on Lspstat.errorfloatYHeHelium abundancephys.abund.Yfloate_YHeUncertainty on YHestat.errorfloatvmicroMicroturbulence velocitykm/sphys.veloc.microTurbintlogQWind-strength parameterstat.fit.paramfloatQualQuality GBAT analysismeta.code.qual;obs.paramcharNspNumber of spectrameta.numberintVarDetected variabilitymeta.code;src.varcharRWRunaway statusmeta.codechar_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainJ/A+A/711/A151/normheResults for the normal He sampleSimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStar-IDStar identifiermeta.id;meta.maincharSpClassSpectral classsrc.spTypecharvsiniProjected rotational velocitykm/sphys.veloc.rotatintvmacMacroturbulent velocitykm/sphys.velocintTeffEffective temperaturekKphys.temperature.effectivefloate_TeffUndertainty on TeffkKstat.error;phys.temperature.effectivefloatloggSurface gravitylog(cm.s**-2)phys.gravityfloate_loggUncertainty on logglog(cm.s**-2)stat.errorfloatlogLspSpectroscopic luminosityphys.luminosityfloate_logLspUncertainty on Lspstat.errorfloatYHeHelium abundancephys.abund.Yfloate_YHeUncertainty on YHestat.errorfloatvmicroMicroturbulence velocitykm/sphys.veloc.microTurbintlogQWind-strength parameterstat.fit.paramfloatQualQuality GBAT analysismeta.code.qual;obs.paramcharNspNumber of spectrameta.numberintVarDetected variabilitymeta.code;src.varcharRWRunaway statusmeta.codechar_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainJ/A+A/711/A151/lowheResults for the low He sampleSpClassSpectral classsrc.spTypecharSimbadSimbad column added by the CDSmeta.ref.urlchar_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.mainrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintvsiniProjected rotational velocitykm/sphys.veloc.rotatintStar-IDStar identifiermeta.id;meta.maincharvmacMacroturbulent velocitykm/sphys.velocintTeffEffective temperaturekKphys.temperature.effectivefloate_TeffUndertainty on TeffkKstat.error;phys.temperature.effectivefloatloggSurface gravitylog(cm.s**-2)phys.gravityfloate_loggUncertainty on logglog(cm.s**-2)stat.errorfloatlogLspSpectroscopic luminosityphys.luminosityfloate_logLspUncertainty on Lspstat.errorfloatYHeHelium abundancephys.abund.Yfloate_YHeUncertainty on YHestat.errorfloatvmicroMicroturbulence velocitykm/sphys.veloc.microTurbintlogQWind-strength parameterstat.fit.paramfloatQualQuality GBAT analysismeta.code.qual;obs.paramcharNspNumber of spectrameta.numberintVarDetected variabilitymeta.code;src.varcharRWRunaway statusmeta.codechar_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.main