J/ApJS/205/5ivo://CDS.VizieR/J/ApJS/205/5doi:10.26093/cds/vizier.22050005CDSHsieh T.-H.Lai S.-P.2018-01-22T09:18:00Z2013-04-29T11:51:46ZCDS support team

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

cds-question@unistra.fryoung-stellar-objectspre-main-sequence-starsmolecular-cloudsWe develop a new method for identifying young stellar objects (YSOs) from star-forming regions using the photometry data from Spitzer's c2d Legacy Project. The aim is to obtain YSO lists as complete as possible for studying statistical properties such as the star formation rate (SFR) and lifetimes of YSOs in different evolutionary stages. The largest obstacle in identifying YSOs comes from background galaxies with similar spectral energy distributions to YSOs. Traditionally, selected color-color and color-magnitude criteria are used to separate YSOs and galaxies. However, since there is no obvious boundary between YSOs and galaxies in color-color diagrams and color-magnitude diagrams (CMDs), those criteria may exclude faint YSOs near the boundary. In this paper, we separate the YSOs and galaxies in a multi-dimensional (multi-D) magnitude space, which is equivalent to using all variations of CMDs simultaneously. Comparing sources from molecular clouds to Spitzer's SWIRE data, which have a negligible amount of YSOs, we can naturally identify YSO candidates (YSOc) located outside of the galaxy-populated regions in the multi-D space. In the five c2d surveyed clouds, we select 322 new YSOc and miss/exclude 33 YSOc compared to Evans et al. (2009, Cat. J/ApJS/181/321), and this results in 1313 YSOc in total. As a result, SFR increases 28% correspondingly, but the lifetimes of YSOs in different evolutionary stages remain unchanged. Compared to theories by Krumholz & McKee (2005ApJ...630..250K), our derived SFR suggests that star formation at a large scale is dominated by supersonic turbulence rather than magnetic fields. Furthermore, we identify seven new very low luminosity objects.2013ApJS..205....5Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/205/5CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/290 : SWIRE Photometric Redshift Catalogue (Rowan-Robinson+, 2008)J/MNRAS/410/2662 : AMI 1.8cm observations in c2d small clouds (Scaife+, 2011)J/MNRAS/415/893 : AMI-LA 16 GHz sources in Perseus region (Scaife+, 2011)J/ApJ/724/835 : The Spitzer c2d survey of WTTSs. III. (Wahhaj+, 2010)J/ApJS/181/321 : Properties of Spitzer c2d dark clouds (Evans+, 2009)J/ApJS/177/551 : Spitzer c2d survey of Lupus dark clouds (Merin+, 2008)J/A+A/487/993 : MAMBO Mapping of c2d Clouds and Cores (Kauffmann+, 2008)J/ApJ/676/427 : MIPS and IRAC data on ChaII PMS stars (Alcala+, 2008)J/AJ/133/1560 : Spitzer c2d small clouds and cores (Wu+, 2007)J/ApJ/663/1149 : Spitzer survey of Serpens YSO population (Harvey+, 2007)J/ApJ/667/308 : Weak-line T Tauri in Spitzer c2d Survey. II. (Cieza+, 2007)J/ApJ/638/293 : 1.1mm sources in the Perseus Molecular Cloud (Enoch+, 2006)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/205/5https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJS/205/5http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJS/205/5https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJS/205/5https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJS/205/5http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJS/205/5GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJS/205/5/table2 (YSO candidates in 5 nearby molecular clouds)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/205/5/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/205/5/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/205/5/table2?GETtext/xml+votable180.050000true51.196807230.46560860.0055555555555555565/7590 10649 10653 10745 6/855 857 858 859 860 861 862 881 1538 1539 1542 1544 30366 30388 41126 41127 41132 41133 41134 42611 42621 42727 42736 42738 42739 42744 42957 42959 42966 42967 42969 42970 42971 42972 42988 42989 42992 42993 42994 43000https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJS/205/5?format=asciidefaultJ/ApJS/205/5/table2YSO candidates in 5 nearby molecular cloudsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintCloudCloud identifier (Chamaeleon II, Lupus, Ophiuchus, Perseus or Serpens)meta.id.parentcharRAJ2000Right Ascension in decimal degrees (J2000)degpos.eq.ra;meta.mainDEJ2000Declination in decimal degrees (J2000)degpos.eq.dec;meta.maingalP1[-4.16/1.4]? log of galaxy probability 1 (1)stat.fit.paramfloatnullablef_galP1[-inf, sat, cde] Flag on galP1 (4)meta.codechargalP2[-3.33/2.45]? log of galaxy probability 2 (1)stat.fit.paramfloatnullablef_galP2[-inf] -inf = -infinity (probability=0)meta.codechargalP1p[-4.16/1.54]? log of galaxy probability 1p (1)stat.fit.paramfloatnullablef_galP1p[-inf] -inf = -infinity (probability=0)meta.codechargalP2p[-3.76/2.85]? log of galaxy probability 2p (1)stat.fit.paramfloatnullablef_galP2p[-inf] -inf = -infinity (probability=0)meta.codecharDen[-0.95/3.65]? log of stellar densitylog(pc**-2)pos.distancefloatnullableYSOP[0/2.31]? YSO probability (1)stat.fit.paramfloatnullableClassc2d classification (2)src.classcharf_Class[ab] Flag on Class (3)meta.codecharScatCross-match with Evans+, Cat. J/ApJS/181/321, within 1.5"meta.ref.urlintnullableSimbadSimbad column added by the CDSmeta.ref.urlchar