J/A+AS/121/213ivo://CDS.VizieR/J/A+AS/121/213CDSPanagi P.M.O'Dell M.A.2013-03-06T06:34:46Z1997-12-09T19:24:54ZCDS support team

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

cds-question@unistra.fropen-star-clustersphotometryWe present the results of H{alpha}(6562A) and Li I(6708A) observations of 114 low-mass stars of the young open cluster Blanco 1. We also present observations of 30 stars in Ca II(K). This work extends the first Blanco 1 spectroscopic study of Panagi et al. (1994A&A...285..233D). From a sample of four well-studied clusters, including Blanco 1, we find that the fraction of H{alpha} emission-line stars amongst K dwarfs is a good indicator of relative age, with a smaller fraction indicative of older age. Blanco 1 shows a relatively small fraction of emitters, inconsistent with previous age estimates for the cluster. We estimate the cluster age to to be 90+/-25Myr, slightly older than the Pleiades. The method is shown to be more sensitive to age than lithium and a useful alternative to other age measurement techniques. The variation of H{alpha} with (B-V) is similar to that observed in the older solar neighbourhood dwarfs, suggesting that, at least for the absorption-line stars, the contribution of stellar rotation to the equivalent width is unclear. We combine both spectroscopy and photometry to revise cluster membership and give accurate positions for all these stars.1997A&AS..121..213Phttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+AS/121/213CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+AS/121/213https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+AS/121/213http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+AS/121/213https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+AS/121/213https://vizier.iucaa.in/viz-bin/votable?-source=J/A+AS/121/213http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+AS/121/213GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+AS/121/213/tablea1 (APM positions of proposed members of the open-cluster Blanco 1.)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+AS/121/213/tablea1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+AS/121/213/tablea1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+AS/121/213/tablea1?GETtext/xml+votable180.050000true359.9572821-30.63207410.005555555555555556Cone search capability for table J/A+AS/121/213/tablea2 (Positions of stars/objects classified as non-members.)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+AS/121/213/tablea2?https://vizier.iucaa.in/viz-bin/conesearch/J/A+AS/121/213/tablea2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+AS/121/213/tablea2?GETtext/xml+votable180.050000true359.9572496-29.85243630.0055555555555555565/4122 6/16447 16483 16492 16576-16577https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+AS/121/213?format=asciiOpticaldefaultJ/A+AS/121/213/tablea1APM positions of proposed members of the open-cluster Blanco 1.recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintZS? ZS number (de Epstein & Epstein (1985))meta.idintnullablem_ZSMultyiplicity index on ZSmeta.code.multipcharn_ZSNote on ZS (1)meta.notecharRA1950Right ascension 1950.0pos.eq.ra;meta.mainDE1950Declination 1950.0pos.eq.dec;meta.mainVmagV magnitudemagphot.mag;em.opt.VfloatB-VB-V color indexmagphot.color;em.opt.B;em.opt.VfloatNameOther designations (2)meta.id;meta.mainchar_RA.icrsRight ascension (ICRS) (computed by VizieR, not part of the original data)pos.eq.ranullableindexed_DE.icrsDeclination (ICRS) (computed by VizieR, not part of the original data)pos.eq.decnullableindexedJ/A+AS/121/213/tablea2Positions of stars/objects classified as non-members.recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintZSZS number (de Epstein & Epstein, 1985)meta.id;meta.mainintWest? Westerlund number (Westerlund et al. (1988))meta.idintnullableRA1950Right ascension 1950.0pos.eq.ra;meta.mainDE1950Declination 1950.0pos.eq.dec;meta.mainVmagV magnitudemagphot.mag;em.opt.VfloatB-VB-V color indexmagphot.color;em.opt.B;em.opt.VfloatRemRemarks (1)meta.notechar_RA.icrsRight ascension (ICRS) (computed by VizieR, not part of the original data)pos.eq.ranullableindexed_DE.icrsDeclination (ICRS) (computed by VizieR, not part of the original data)pos.eq.decnullableindexed