J/ApJ/704/606ivo://CDS.VizieR/J/ApJ/704/606doi:10.26093/cds/vizier.17040606CDSGiannini T.Lorenzetti D.Elia D.Strafella F.De Luca M.Fazio G.,Marengo M.Nisini B.Smith H.A.2017-11-29T11:48:20Z2011-11-23T10:24:43ZCDS support team

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

cds-question@unistra.frmolecular-cloudsyoung-stellar-objectsinfrared-photometryWe present a study of the infrared variability of young stellar objects by means of two Spitzer-IRAC images of the Vela Molecular Cloud D (VMR-D) obtained in observations separated in time by about six months. By using the same space-born IR instrumentation, this study eliminates all the unwanted effects due to differences in sensitivity, confusion, saturation, calibration, and filter bandpasses, issues that are usually unavoidable when comparing catalogs obtained from different instruments. The VMR-D map covers about 1.5deg^2^ of a site where star formation is actively ongoing. We are interested in accreting pre-main sequence variables whose luminosity variations are due to intermittent events of disk accretion (i.e., active T Tauri stars and EXor-type objects). The variable objects have been selected from a catalog of more than 170000 sources detected at an S/N>=5 (Cat. J/ApJ/719/9). We then searched the sample of variables for ones whose photometric properties such as IR excess, color-magnitude relationships, and spectral energy distribution, are as close as possible to those of known EXor's. Indeed, the latter are monitored in a more systematic way than T Tauri stars and the mechanisms that regulate the observed phenomenology are exactly the same. Hence, the modalities of the EXor behavior are adopted as driving criterion for selecting variables in general. We ultimately selected 19 bona fide candidates that constitute a well defined sample of new variable targets for further investigation (monitoring, spectroscopy). Out of these, 10 sources present a Spitzer MIPS 24um counterpart, and have been classified as three Class I, five flat spectrum, and two Class II objects, while the spectral energy distribution of the other nine sources is compatible with evolutionary phases older than Class I.2009ApJ...704..606Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/704/606CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)J/ApJ/719/9 : Pre-main sequence variables in the VMR-D (Strafella+, 2010)J/ApJ/671/470 : MIPS survey of YSOs in Vela Molecular Ridge-D (Giannini+,J/A+AS/136/471 : JHK photometry of D-cloud IRAS sources (Massi+, 1999)J/A+AS/104/233 : Emission-line stars in Vela Molecular Ridge (Pettersson+ 1994)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/704/606https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/704/606http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/704/606https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/704/606https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/704/606http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/704/606GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/704/606/table2 (Magnitudes of the 47 selected variables at the 2 epochs (2007-02-21 and 2007-07-04))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/704/606/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/704/606/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/704/606/table2?GETtext/xml+votable180.050000true131.37375-43.8466940.0055555555555555565/98126.772611666688002e-21 1.7003137259100215e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/704/606?format=asciiInfrareddefaultJ/ApJ/704/606/table2Magnitudes of the 47 selected variables at the 2 epochs (2007-02-21 and 2007-07-04)2MDisplay the 2MASS data (Cutri et al. 2003, Cat. II/246)meta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint[SEC2010]Identification number (<[SEC2010] IRAC NNNNNN> in Simbad)meta.id;meta.mainintRAJ2000Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of declination (J2000)pos.eq.dec;meta.mainJmag? 2MASS J-band magnitude (1)magphot.mag;em.IR.JfloatnullableHmag? 2MASS H-band magnitude (1)magphot.mag;em.IR.HfloatnullableKsmag? 2MASS Ks-band magnitude (1)magphot.mag;em.IR.Kfloatnullable[3.6]Spitzer/IRAC 3.6um-band magnitude (1)magphot.mag;em.IR.3-4umfloat[4.5]Spitzer/IRAC 4.5um-band magnitude (1)magphot.mag;em.IR.4-8umfloat[5.8]? Spitzer/IRAC 5.8um-band magnitude (1)magphot.flux.density;em.IR.4-8umfloatnullable[8.0]? Spitzer/IRAC 8.0um-band magnitude (1)magphot.flux.density;em.IR.8-15umfloatnullable[24]? Spitzer/MIPS 24um-band magnitude counterpart (1)magphot.flux.density;em.IR.15-30umfloatnullableS10Display the VMR-D IRAC catalog (Strafella et al. 2010, Cat. J/ApJ/719/9)meta.ref.urlcharSimbadSimbad column added by the CDSmeta.refcharJ/ApJ/704/606/table3Coded photometric properties of the selected sourcesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint[SEC2010]Identification numbermeta.id;meta.mainintprimaryf_[SEC2010][c] c: Candidate young variablemeta.codecharLocSource location (1)meta.codecharClassYSO vs. other (AGB, XGAL (extragalactic), or PHT (photosphere))src.classcharDelmag[CDI] {Delta}mag vs {lambda} (D: decreasing, C: constant or I: Increasing)meta.codecharDifmag[0+-] Evolution of [3.6]-[4.5] vs. [4.5] (2)meta.codecharERatio of the observed SED and the underlying normalized K5-M5 photosphere (3)stat.fit.omcfloatLiracIRAC luminositysolLumphys.luminosity;em.IRfloat