J/A+AS/124/449ivo://CDS.VizieR/J/A+AS/124/449CDSMagazzu A.Martin E.L.Sterzik M.F.Neuhaeuser R.Covino E.,Alcala J.M.2001-07-02T12:08:20Z2001-07-02T12:08:13ZCDS support team

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

cds-question@unistra.frx-ray-sourcespre-main-sequence-starsapparent-magnitudeWe present results of intermediate resolution spectroscopy of 131 optical counterparts to 115 ROSAT All-Sky Survey X-ray sources south of the Taurus-Auriga dark cloud complex. These objects have been selected as candidate young stars from a total of 1084 ROSAT sources in a ~300 square degree area. We identify 30 objects as low-mass PMS stars on the basis of the LiI{lambda}6708{AA} doublet in their spectrum, a signature of their young age. All these stars have a spectral type later than F7 and show spectral characteristics typical of weak-line and post-T Tauri stars. The presence of young objects several parsecs away from the regions of ongoing star formation is discussed in the light of the current models of T Tauri dispersal.1997A&AS..124..449Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+AS/124/449CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+AS/124/449https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+AS/124/449http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+AS/124/449https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+AS/124/449https://vizier.iucaa.in/viz-bin/votable?-source=J/A+AS/124/449http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+AS/124/449GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+AS/124/449/table2 (Closest optical counterparts.)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+AS/124/449/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/A+AS/124/449/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+AS/124/449/table2?GETtext/xml+votable180.050000true31.76225-14.11444440.005555555555555556Cone search capability for table J/A+AS/124/449/table3 (Other optical counterparts observed.)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+AS/124/449/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/A+AS/124/449/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+AS/124/449/table3?GETtext/xml+votable180.050000true32.60833-13.132220.0055555555555555566/18 81 87 92 257-258 261 263 267 272 22957 22963 23135 23154 23166 23198 23205 23222 23225 23247 23253 23256 23259-23260 23262 23266-23267 23269 23281 23288 23293-23294 23298-23299 23302 23304 23306 23315 23323-23324 23346 23363 23370-23371 23387 23393 23395-23396 23398 23404 23418 23425-23427 23434 23438 23445 23447 23451 23457 23462 23464 23466-23468 23472 23478 23480 23490 23497 23721 23725-23726 23738-23739 24064 24066 24069-24070 24076 36562 36571 36580 36582 36592-36594 36596 36746 36749 36752 36763 36776 36799 36808-36809 36823 36828 36858https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+AS/124/449?format=asciiX-raydefaultJ/A+AS/124/449/table1X-ray data for our samplee_Countsrms uncertainty on Countsstat.errorfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintROSATROSAT (Cat. <IX/11>) namemeta.id;meta.maincharprimaryCountsNumber of counts in the broad ROSAT bandphot.count;em.X-rayfloatExpExposure timestime.duration;obs.exposurefloatHR1Hardness ratio 1phot.flux;arith.ratiofloate_HR1rms uncertainty on HR1stat.errorfloatHR2Hardness ratio 2phot.flux;arith.ratiofloate_HR2rms uncertainty on HR2stat.errorfloatMLMaximum likelihood of existencestat.likelihoodfloatkTxEmission energy (typical error +/-0.55keV)keVem.energyfloatlog(NH)Absorbing foreground column density (typical error +/-0.77, in log(N_H_) cm^-2^)log(cm**-2)phys.columnDensityfloatFXX-ray flux (typical error+/-1.87x10^-13^mW/m2)1e-13mW.m**-2phot.flux;em.X-rayfloatJ/A+AS/124/449/table2Closest optical counterparts.recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintROSATROSAT namemeta.id;meta.maincharm_ROSATMultiplicity index on ROSAT namemeta.code.multipcharRAJ2000Optical right ascension (J2000.0) (1)pos.eq.ra;meta.mainDEJ2000Optical declination (J2000.0) (1)pos.eq.dec;meta.mainoRAOffset between X-ray and optical right ascensionarcsecpos.eq.ra;arith.difffloatoDEOffset between X-ray and optical declinationarcsecpos.eq.dec;arith.difffloatVmagV magnitude (from the GSC <II/143> or Simbad if n_Vmag=:)magphot.mag;em.opt.Vfloatn_Vmag[:] : indicates that V magnitude is from Simbadmeta.notecharlog(FX/FV)X-ray to optical flux ratiophot.flux;arith.ratiofloatProbDiscrimination probabilitystat.fit.goodnessfloatRemRemarks (2)meta.notecharJ/A+AS/124/449/table3Other optical counterparts observed.recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintROSATROSAT namemeta.id;meta.maincharm_ROSATMultiplicity index on ROSAT namemeta.code.multipcharRAJ2000Optical right ascension (J2000.0)pos.eq.ra;meta.mainDEJ2000Optical declination (J2000.0)pos.eq.dec;meta.mainPosRelative position to the counterpart listed in Table 2pos.eqcharVmagV magnitude (from the GCS)magphot.mag;em.opt.VfloatRemRemarks (1)meta.notecharJ/A+AS/124/449/table4Results of spectroscopy of all counterpartsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintROSATROSAT namemeta.id;meta.maincharm_ROSATMultiplicity index on ROSAT namemeta.code.multipcharTelTelescope used (1)meta.id;instr.telcharEW(Halpha)?H{alpha} equivalent width (negative when in emission)0.1nmspect.line.eqWidthfloatnullablen_EW(Halpha)[af] Note on EW(Halpha) (2)meta.notecharEW(Li)?Lithium 6708{AA} absorption equivalent width0.1nmspect.line.eqWidthfloatnullablen_EW(Li)[:ny] Note on EW(Li) (3)meta.notecharSpTypeSpectral type (always luminosity class V unless otherwise noted)src.spTypecharNatureNature of object (see text)src.classcharRemIndividual notes (4)meta.notechar