J/ApJ/885/64ivo://CDS.VizieR/J/ApJ/885/64doi:10.26093/cds/vizier.18850064CDSEllithorpe E.A.Duchene G.Stahler S.W.2021-07-05T13:37:50Z2021-06-21T08:33:30ZCDS support team

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

cds-question@unistra.fryoung-stellar-objectspre-main-sequence-starsinfrared-astronomyWe present a quantitative, empirically based argument that at least some Class I sources are low-mass, pre-main-sequence stars surrounded by spatially extended envelopes of dusty gas. The source luminosity arises principally from stellar gravitational contraction, as in optically visible pre-main-sequence stars that lack such envelopes. We base our argument on the fact that some Class I sources in Orion and other star-forming regions have been observed by Spitzer to be periodic variables in the mid-infrared, and with periods consistent with T Tauri rotation rates. Using a radiative transfer code, we construct a variety of dust envelopes surrounding rotating, spotted stars, to see whether an envelope that produces a Class I spectral energy distribution at least broadly matches the observed modulations in luminosity. Acceptable envelopes can be either spherical or flattened and may or may not have polar cavities. The key requirement is that they have a modest equatorial optical depth at the Spitzer waveband of 3.6{mu}m, typically {tau}3.6~0.6. The total envelope mass, based on this limited study, is at most about 0.1M{sun}, less than a typical stellar mass. Future studies should focus on the dynamics of the envelope, to determine whether material is actually falling onto the circumstellar disk.2019ApJ...885...64Ehttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/885/64CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)J/ApJS/101/117 : UBVRIJHKLMNQ photometry in Taurus-Auriga (Kenyon+ 1995)J/AJ/130/1145 : YSO near-infrared properties (Doppmann+, 2005)J/AJ/140/1214 : Near-IR spectroscopic survey of class I YSOs (Connelley+,2010)J/ApJ/733/50 : Mid-IR photometric monitoring of ONC (Morales-Calderon+, 2011)J/AJ/144/192 : Spitzer survey of Orion A & B. I. YSO catalog (Megeath+, 2012)J/A+A/570/A29 : TBOSS Survey I: Herschel/PACS (Bulger+, 2014)J/AJ/147/82 : Monitoring of disk-bearing stars in NGC 2264 (Cody+, 2014)J/AJ/148/122 : YSOVAR: infrared photometry in Lynds 1688 (Gunther+, 2014)J/AJ/150/118 : YSOVAR IR photometry in IRAS 20050+2720 (Poppenhaeger+, 2015)J/AJ/150/175 : YSOVAR: infrared photometry in NGC 1333 (Rebull+, 2015)J/AJ/150/145 : YSOVAR infrared photometry in GGD12-15 (Wolk+, 2015)J/ApJS/224/5 : The Herschel Orion Protostar Survey: SEDs (Furlan+, 2016)J/ApJ/821/52 : NIR survey of Spitzer YSOs in Orion Mol. Cloud (Kounkel+,2016)J/A+A/590/A33 : Class 0 sources continuum subtracted UV-tables (Persson+,2016)J/ApJ/849/63 : FIR-mm data of YSOs in star-forming regions (Ribas+, 2017)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/885/64https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/885/64http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/885/64https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/885/64https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/885/64http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/885/64GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/885/64/table5 (Amplitude of variability for 150 YSOs in Orion)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/885/64/table5?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/885/64/table5?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/885/64/table5?GETtext/xml+votable180.050000true83.6154275-5.53203560.0055555555555555566/21438 21439 22805https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/885/64?format=asciiInfrareddefaultJ/ApJ/885/64/table5Amplitude of variability for 150 YSOs in OrionSimbadNameSimbad column added by the CDSmeta.idcharNoteNote (1)meta.notecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarTarget namemeta.id;meta.maincharClassClassificationsrc.class.starGalaxycharPeriod[1.05/24.8] Perioddtime.periodfloatalpha[-0.26/0.39] Amplitude of variation at 3.6micronmagsrc.var.amplitudefloaterror[1.06/15.6] Reduced chi square errormagstat.errorfloat_RAPosition from SIMBAD (right ascension part)degpos.eq.ra;meta.main_DEPosition from SIMBAD (declination part)degpos.eq.dec;meta.main