J/MNRAS/356/89ivo://CDS.VizieR/J/MNRAS/356/89doi:10.26093/cds/vizier.73560089CDSKenyon M.J.Jeffries R.D.Naylor T.Oliveira J.M.Maxted P.F.L.2024-06-30T20:17:03Z2007-05-01T19:51:24ZCDS support team

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

cds-question@unistra.fropen-star-clusterspre-main-sequence-starsdwarf-starsradial-velocityline-intensitiesphotometryIntermediate-resolution (R~7000) spectroscopy is presented for 76 photometrically selected very low-mass (0.04<M<0.3M_{sun}_) candidate members of the young cluster around sigma Orionis (sigma Ori). More than two-thirds appear to be genuine cluster members on the basis that they exhibit Li I 6708{AA} absorption, weak Na I 8183/8195{AA} features and a radial velocity consistent with the cluster mean. Photometric selection alone therefore appears to be very effective in identifying cluster members in this mass range. Only six objects appear to be certain non-members; however, a substantial subset of 13 candidates have ambiguous or contradictory indications of membership and lack Li absorption. Together with an observed spread in the equivalent width of the Li absorption feature in the cooler stars of our sample, this indicates that there may be deficiencies in our understanding of the formation of this line in cool, low-gravity objects.2005MNRAS.356...89Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/356/89CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/MNRAS/356/1583 : Sigma Ori low-mass candidate members (Burningham+, 2005)J/A+A/419/249 : RJHKs phot. of sigma Ori low-mass stars (Scholz+, 2004)J/AJ/128/2316 : BVRIJHKs photometry in sigma Ori cluster (Sherry+, 2004)J/AN/325/705 : RIJHKs of low-mass stars in sigma Ori (Bejar+, 2004)J/MNRAS/346/1143 : VI photometry of Collinder 121 (Burningham+, 2003)J/MNRAS/351/1401 : RcIcZ photometry of NGC 2547 (Jeffries+, 2004)J/A+A/436/853 : IR phot. of Alpha Per low-mass members (Lodieu+, 2005)J/MNRAS/358/341 : Ic photometry of IC 348 (Littlefair+, 2005)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/356/89https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/356/89http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/356/89https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/356/89https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/356/89http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/356/89GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/356/89/catalog (RI photometry in the region of {sigma} Ori)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/356/89/catalog?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/356/89/catalog?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/356/89/catalog?GETtext/xml+votable180.050000true84.98095417-2.622538890.005555555555555556Cone search capability for table J/MNRAS/356/89/sigOri (Results of the {sigma} Ori cluster investigation)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/356/89/sigOri?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/356/89/sigOri?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/356/89/sigOri?GETtext/xml+votable180.050000true84.6822917-2.87855560.0055555555555555566/22849 22851-22852 22854 22857 22860https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/356/89?format=asciiOpticaldefaultJ/MNRAS/356/89/catalogRI photometry in the region of {sigma} OrirecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFieldField and CCD number (1)meta.id;obs.fieldfloatStarStar number in the fieldmeta.id;obs.fieldintRAJ2000Right ascension (J2000)pos.eq.ra;meta.mainindexedDEJ2000Declination (J2000)pos.eq.dec;meta.mainindexedXposX positionpixpos.cartesian.xdoubleYposY positionpixpos.cartesian.y;instr.detdoubleIcmag? Cousins I magnitudemagphot.mag;em.opt.Ifloatnullablee_Icmag? rms uncertainty on Icmagmagstat.error;phot.mag;em.opt.Ifloatnullablef_IcmagFlag for Icmag (in flag.dat file; O=OK)meta.codecharfRFlag for Rcmag (in flag.dat file; O=OK)meta.codecharRc-Ic? Cousins R-I colour indexmagphot.color;em.opt.R;em.opt.Ifloatnullablee_Rc-Ic? rms uncertainty on R-Imagstat.error;phot.color;em.opt.RfloatnullableJ/MNRAS/356/89/flagsFlagsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFlagFlag code (1)meta.code.errorcharExplaFlag meaningmeta.notecharAlgoAlgorithm usedmeta.notecharTypeType (Strong or Weak)meta.notecharFNum? Flag number for the older versions of the softwaremeta.codeintnullableJ/MNRAS/356/89/sigOriResults of the {sigma} Ori cluster investigatione_HRV1? rms uncertainty on HRV1km/sstat.errorintnullablef_HRV1[OO AA] OO: OK, AA: Absent input datameta.codecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStSimbad column added by the CDSmeta.code.memberchar[KJN2005]Sequential numbermeta.recordintRAJ2000Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainIcmagCousins I magnitudemagphot.mag;em.opt.Ifloate_Icmagrms uncertainty on Icmagmagstat.error;phot.mag;em.opt.Ifloatf_Icmag[OO] OO: OKmeta.codecharRc-IcCousins R-I colour indexmagphot.color;em.opt.R;em.opt.Ifloate_Rc-Icrms uncertainty on Rc-Icmagstat.error;phot.color;em.opt.Rfloatf_Rcmag[OO] OO: OKmeta.codecharHRV1? Heliocentric radial velocity on night 1km/sspect.dopplerVeloc;pos.heliocentricintnullableHRV2? Heliocentric radial velocity on night 2km/sspect.dopplerVeloc;pos.heliocentricintnullablee_HRV2? rms uncertainty on HRV2km/sstat.errorintnullablef_HRV2[OO AA] OO: OK, AA: Absent input datameta.codecharEWLi? LiI (6708{AA}) equivalent width0.1nmspect.line.eqWidthfloatnullablee_EWLi? rms uncertainty on EWLi0.1nmstat.errorfloatnullablef_EWLi[OO UU] OO: OK, UU: Uncertainmeta.codecharEWNa? NaI (8183/8195{AA}) equivalent width0.1nmspect.line.eqWidthfloatnullablee_EWNa? rms uncertainty on EWNa0.1nmstat.errorfloatnullablef_EWNa[OO] OO: OKmeta.codechar[BMZ2001]Name from Bejar et al. (2001ApJ...556..830B) S Ori JHHMMSS.s+DDMMSSmeta.idchar[BZR99]Name from Bejar et al. (1999ApJ...521..671B) S Ori NNmeta.idchar