J/A+A/317/871ivo://CDS.VizieR/J/A+A/317/871doi:10.26093/cds/vizier.33170871CDSLennon D.J.2021-12-06T13:21:22Z2021-04-12T12:44:06ZCDS support team

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

cds-question@unistra.frmagellanic-cloudsb-starssupergiant-starsmorgan-keenan-classificationThe problem of the classification of metal poor stars, such as occur in the Small Magellanic Cloud (SMC), is discussed with reference to the applicability of the MK system in such an environment. An alternative method is presented here and applied to B-type supergiants in the SMC. A local reference system is first devised and then a transformation to MK spectral types is determined by comparing the trends of metal line strengths in these two systems. For the determination of the luminosity class, we emphasize the need to use the hydrogen Balmer line strengths independently of metal line-strength considerations. This method is used to determine new spectral types for 64 supergiants in the SMC, 75% of the sample requiring classifications different from previous findings. These new types result in much improved line strength - spectral type correlations for He, C, N, O, Mg and Si. Corresponding changes in the distribution of these stars in the Hertzsprung-Russell diagram of the SMC reveal more clearly than before the existence of a ridge which may be the SMC analogue of a similar feature found for the LMC by Fitzpatrick & Garmany (1990ApJ...363..119F). The group of very luminous supergiants lying above this ridge includes the LBV AV415 (R40), a property which this object has in common with LBVs in the Large Magellanic Cloud. Also, for the first time, clear examples of BN/BC supergiants are found in the SMC.1997A&A...317..871Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/317/871CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/317/871https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/317/871http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/317/871https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/317/871https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/317/871http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/317/871GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/317/871/sptypes (Revised spectral types for 64 early-type supergiants as listed in Table 2 of the paper)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/317/871/sptypes?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/317/871/sptypes?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/317/871/sptypes?GETtext/xml+votable180.050000true10.7985253-73.38631890.0055555555555555566/32958 33294-33295 33298 33304-33306 33317 33319 33328 33330https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/317/871?format=asciiOpticaldefaultJ/A+A/317/871/sptypesRevised spectral types for 64 early-type supergiants as listed in Table 2 of the paperrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameSimbad name of sourcemeta.id;meta.maincharSpTypeRevised Spectral Typesrc.spTypecharSimbadSimbad 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.main