J/MNRAS/465/1227ivo://CDS.VizieR/J/MNRAS/465/1227doi:10.26093/cds/vizier.74651227CDSDesforges S.St-Louis N.Chene A.-N.de la Chevrotiere A.,Henault-Brunet V.2024-08-16T20:19:42Z2018-11-15T16:05:36ZCDS support team

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

cds-question@unistra.frwolf-rayet-starsline-intensitiesradial-velocityWe present the results of a spectroscopic monitoring campaign of nine presumably single Wolf-Rayet (WR) stars, eight of type WC 9 and one WC 8d. We characterize their variability and search for clues to the mechanism responsible for the formation of dust in their wind. For seven out of eight WC 9s, we find a large-scale line-flux variability level of {sigma}>5-8 per cent. The only WC 8d star is variable at a level more comparable with those associated with wind clumping, {sigma}=2.2 per cent. The changes take place on a time-scale of days but in many cases, observing over longer time spans resulted in higher line-flux variability levels. The width of the substructures ranges from ~150 to 300km/s, with the widest structures corresponding to stars with the highest variability amplitude. We searched for periodicities in integrated line quantities for CIII {lambda}5696. Radial velocity changes are typically ~20km/s but never exceed 40km/s and are anticorrelated with the skewness of the line, strongly suggesting that they do not correspond to a real movement of the star. No periodicity was found in these integrated quantities, except for WR 103. Therefore, a wind-wind collision in a close binary does not seem to be responsible for the short-term variability. We cannot, however, exclude that these stars are intermediate- to long-period binaries. We estimate that for periods up to a few years, the shock-cone resulting from wind collisions would be non-adiabatic and thus unstable. We suggest that this represents a viable mechanism to explain the spectroscopic variability.2017MNRAS.465.1227Dhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/465/1227CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toIII/215 : 7th Catalog of Galactic Wolf-Rayet stars (van der Hucht, 2001)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/465/1227https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/465/1227http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/465/1227https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/465/1227https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/465/1227http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/465/1227GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/465/1227/table1 (Our WC 9 stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/465/1227/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/465/1227/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/465/1227/table1?GETtext/xml+votable180.050000true202.72188-62.08107110.0055555555555555566/28726 28919 29524 30256 41697 41745 42295 42371 42481https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/465/1227?format=asciidefaultJ/MNRAS/465/1227/table1Our WC 9 starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar namemeta.id;meta.maincharSpTypeSpectral type (1)src.spTypecharn_SpTypeNote on SpType (2)meta.notecharvmagMagnitude in Smith system (1968MNRAS.138..109S) (1)magphot.mag;em.opt.VfloatNELONumber of ELO spectrameta.numberintS/NELOAverage signal-to-noise ration (continuum) for ELO runstat.snr;stat.meanintNOMM? Number of OMM spectrameta.numberintnullableS/NOMM? Average signal-to-noise ration (continuum) for OMM runstat.snr;stat.meanintnullableSimbadSimbad column added by the CDSmeta.ref.urlchar_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/MNRAS/465/1227/table3Average moments and standard deviationsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar namemeta.id;meta.maincharInstELO or OMMmeta.id;instrcharEWAverage equivalent width0.1nmspect.line.eqWidth;stat.meanfloats_EWStandard deviation of EW0.1nmstat.stdev;spect.line.eqWidthfloatSkewAverage Skewnesssrc.morph.param;stat.meanfloats_SkewStandard deviation of Skewstat.stdevfloatKurAverage Kurtosisstat.fit.param;stat.meanfloats_KurStandard deviation of Kurstat.stdevfloatRVAverage radial velocitykm/sspect.dopplerVeloc;stat.meanfloats_RVStandard deviation of RVkm/sstat.stdevfloatJ/MNRAS/465/1227/table4Measurements of integrated line quantitiesKurKurtosisstat.fit.paramfloate_Kurrms uncertainty on Kurstat.errorfloatRVRadial velocitykm/sspect.dopplerVelocfloate_RVrms uncertainty on RVkm/sstat.errorfloatNameStar namemeta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintInstELO or OMMmeta.id;instrcharHJDHeliocentric Julian date (HJD-2451544.5)dtime.epochfloatEWEquivalent width0.1nmspect.line.eqWidthfloate_EWrms uncertainty on EW0.1nmstat.error;spect.line.eqWidthfloatSkewSkewnesssrc.morph.paramfloate_Skewrms uncertainty on Skewstat.errorfloat