J/AJ/121/2124ivo://CDS.VizieR/J/AJ/121/2124doi:10.26093/cds/vizier.51212124CDSDolan C.J.Mathieu R.D.2023-04-06T16:50:41Z2009-04-28T10:57:30ZCDS support team

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

cds-question@unistra.frpre-main-sequence-starsinfrared-photometryvisible-astronomyphotometryccd-photometrymedium-band-photometryline-intensitiesradial-velocityThe {lambda} Ori star-forming region presents a snapshot of a moderate-mass giant molecular cloud 1-2Myr after cloud disruption by OB stars, with the OB stars, the low-mass stellar population, remnant molecular clouds, and the dispersed gas all still present. We have used optical photometry and multiobject spectroscopy for lithium absorption to identify 266 pre-main-sequence stars in 8deg^2^ of the region. We also present new Stroemgren photometry for the massive stars, from which we derive a distance of 450pc and a turnoff age of 6-7Myr. Using these parameters and pre-main-sequence evolutionary models, we map the star formation history of the low-mass stars. We find that low-mass star formation started throughout the region at about the same time as the birth of the massive stars, and thereafter the birth rate accelerated. Within the last 1-2Myr star formation ceased in the center of the star-forming region, near the concentration of OB stars, while it continues in dark clouds 20pc away. We suggest that a supernova 1-2Myr ago destroyed the molecular cloud core from which the OB stars formed, but it did not terminate star formation in more distant reaches of the giant molecular cloud. We find no secure evidence for triggered or sequential star formation in the outer molecular clouds. The global star formation of the {lambda} Ori region has generated the field initial mass function, but local star formation in subregions shows large deviations from the expected ratio of high- to low-mass stars.2001AJ....121.2124Dhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/121/2124CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/121/2124https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/121/2124http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/121/2124https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/121/2124https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/121/2124http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/121/2124GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/121/2124/table1 (Improved data for Paper I (Dolan & Mathieu, 1999, Cat. <J/AJ/118/2409>) stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/121/2124/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/121/2124/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/121/2124/table1?GETtext/xml+votable180.050000true83.446759.927413890.005555555555555556Cone search capability for table J/AJ/121/2124/table2 (Pre-main-sequence stellar data)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/121/2124/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/121/2124/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/121/2124/table2?GETtext/xml+votable180.050000true81.3903458311.646947220.005555555555555556Cone search capability for table J/AJ/121/2124/table4 (Massive star photometry)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/121/2124/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/121/2124/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/121/2124/table4?GETtext/xml+votable180.050000true80.43150118.42855610.005555555555555556Cone search capability for table J/AJ/121/2124/table7 (Follow-up data for DIL (Duerr, Imhoff & Lada, 1982ApJ...261..135D) stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/121/2124/table7?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/121/2124/table7?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/121/2124/table7?GETtext/xml+votable180.050000true79.234420837.270122220.0055555555555555565/5926 5934 6/23005 23030 23587 23590 23682 23693 23695 23697-23699 23703 23708 23711 23714-23717 23719 23724-23725 23727-23730 23732 23734 23740 23776 24080-24081 24083 24085-24086https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/121/2124?format=asciiOpticalInfrareddefaultJ/AJ/121/2124/table1Improved data for Paper I (Dolan & Mathieu, 1999, Cat. <J/AJ/118/2409>) starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint[DM99][1/72] The {lambda} Ori running numbermeta.id;meta.mainintprimaryJNameThe {lambda} Ori designationmeta.idcharRAJ2000Right Ascension from USNO-A 2.0 catalog (J2000)pos.eq.ra;meta.mainDEJ2000Declination from USNO-A 2.0 catalog (J2000)pos.eq.dec;meta.mainVmagThe V band magnitudemagphot.mag;em.opt.VfloatV-RThe (V-R) colormagphot.color;em.opt.V;em.opt.RfloatR-IThe (R-I) colormagphot.color;em.opt.R;em.opt.IfloatLogAgeLog of the Age (1)log(yr)time.agefloatMassMass (1)solMassphys.massfloatf_[DM99][b] Indicates star does not exist in the USNO-A2.0 database. The coordinates (A1.0) and magnitudes listed are from Paper I, Dolan & Mathieu, 1999AJ....118.2409D.meta.codecharPapIShow the values from PaperImeta.ref.urlcharJ/AJ/121/2124/table2Pre-main-sequence stellar data[DM99][73/266] The {lambda} Ori running numbermeta.id;meta.mainintprimaryR-IThe (R-I) colormagphot.color;em.opt.R;em.opt.IfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJNameThe {lambda} Ori designationmeta.idcharRAJ2000Right Ascension from USNO-A 2.0 catalog (J2000)pos.eq.ra;meta.mainDEJ2000Declination from USNO-A 2.0 catalog (J2000)pos.eq.dec;meta.mainVmagThe V band magnitudemagphot.mag;em.opt.Vfloatf_Vmag[c] Indicates photometry from the lower-quality 1998 datameta.codecharV-RThe (V-R) colormagphot.color;em.opt.V;em.opt.Rfloatf_V-R[c] Indicates photometry from the lower-quality 1998 datameta.codecharf_R-I[c] Indicates photometry from the lower-quality 1998 datameta.codecharEqWidLi? Equivalent width of Li (1)0.1nmspect.line.eqWidthfloatnullablef_EqWidLi[gh] Flag on EqWidLi (2)meta.codecharEqWidHa? Equivalent width of H{alpha} (3)0.1nmspect.line.eqWidth;em.line.Halphafloatnullablef_EqWidHa[d] Indicates star shows a strong P Cygni profilemeta.codecharRVelStellar radial velocitykm/sspect.dopplerVeloc;pos.heliocentricfloatf_RVel[fij] Flag on RVel (4)meta.codecharLogAgeLog of the Age (5)log(yr)time.agefloatMassMass (5)solMassphys.massfloatf_Mass[e] Indicates star is outside the age/mass gridmeta.codecharJ/AJ/121/2124/table4Massive star photometryrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHDThe HD (Cat. <III/135>) numbermeta.id;meta.mainintprimaryPPM? The Positions & Proper Motions Catalog (Cat. <I/146>) numbermeta.idintnullableSpTypeSpectral type (1)src.spTypecharf_SpType[b] Flag on SpType (2)meta.codecharVmagThe V band magnitudemagphot.mag;em.opt.Vfloate_VmagUncertainty in Vmagmagstat.error;phot.mag;em.opt.Vfloatb-yThe (b-y) Stroemgren colormagphot.color;em.opt.B;em.opt.Vfloate_b-yUncertainty in (b-y)magstat.error;phot.color;em.opt.Bfloatm1The m_1_ band magnitudemagphot.magfloate_m1Uncertainty in m1magstat.errorfloatc1The c_1_ band magnitudemagphot.mag;em.opt.Vfloate_c1Uncertainty in c1magstat.errorfloato_b-yNumber of Stroemgren uvby observationsmeta.numberintbetaThe {beta} band magnitudemagphot.color;em.opt.B;em.line.Hbetafloate_betaUncertainty in betamagstat.errorfloato_betaNumber of beta observationsmeta.numberintr_HDReference on HDmeta.ref;pos.frameintSimbadSimbad column added by the CDSchar_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/AJ/121/2124/table5Massive star derived datarecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHDThe HD (Cat. <III/135>) numbermeta.id;meta.mainintE(B-V)The E(B-V) reddeningmagphot.color.excessfloatTeffLog of the effective temperaturelog(K)phys.temperature.effectivefloatLumLog of the luminosity in solar unitslog(solLum)phys.luminosityfloatMassLog of the mass in solar unitslog(solMass)phys.massfloatDist? Distancepcpos.distance;pos.heliocentricintnullablee_Dist? The parallax fractional error%stat.errorintnullableJ/AJ/121/2124/table7Follow-up data for DIL (Duerr, Imhoff & Lada, 1982ApJ...261..135D) starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDILThe Duerr, Imhoff & Lada (1982ApJ...261..135D) survey numbermeta.id;meta.mainintUSNO-A2.0The USNO A2.0 identificationmeta.idcharf_USNO-A2.0[abcde] Flag on USNO-A2.0 (1)meta.codecharRAJ2000Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.main[DM99]? This paper's identification numbermeta.idintnullable