J/AJ/165/3ivo://CDS.VizieR/J/AJ/165/3doi:10.26093/cds/vizier/be-55-3CDSKuhn M.A.Saber R.Povich M.S.de Souza R.S.Krone-Martins A.,Ishida E.E.O.Zucker C.Benjamin R.A.Hillenbrand L.A.,Castro-Ginard A.Zhou X.For the COIN collaboration2026-07-02T11:44:34Z2024-01-09T11:47:23ZCDS support team

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

cds-question@unistra.fryoung-stellar-objectsstar-forming-regionsvisible-astronomyspectroscopystellar-spectral-typeseffective-temperaturestellar-massesstellar-agesstellar-radiiextinctionWide-field searches for young stellar objects (YSOs) can place useful constraints on the prevalence of clustered versus distributed star formation. The Spitzer/IRAC Candidate YSO (SPICY) catalog is one of the largest compilations of such objects (~120000 candidates in the Galactic midplane). Many SPICY candidates are spatially clustered, but, perhaps surprisingly, approximately half the candidates appear spatially distributed. To better characterize this unexpected population and confirm its nature, we obtained Palomar/DBSP spectroscopy for 26 of the optically bright (G<15mag) "isolated" YSO candidates. We confirm the YSO classifications of all 26 sources based on their positions on the Hertzsprung-Russell diagram, H and Ca ii line emission from over half the sample, and robust detection of infrared excesses. This implies a contamination rate of <10% for SPICY stars that meet our optical selection criteria. Spectral types range from B4 to K3, with A-type stars being the most common. Spectral energy distributions, diffuse interstellar bands, and Galactic extinction maps indicate moderate-to-high extinction. Stellar masses range from ~1 to 7M{sun}, and the estimated accretion rates, ranging from 3x10^-8^ to 3x10^-7^M{sun}/yr, are typical for YSOs in this mass range. The 3D spatial distribution of these stars, based on Gaia astrometry, reveals that the "isolated" YSOs are not evenly distributed in the Solar neighborhood but are concentrated in kiloparsec-scale dusty Galactic structures that also contain the majority of the SPICY YSO clusters. Thus, the processes that produce large Galactic star-forming structures may yield nearly as many distributed as clustered YSOs.2023AJ....165....3Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/165/3CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/259 : The Tycho-2 Catalogue (Hog+ 2000)II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)II/314 : UKIDSS-DR8 LAS, GCS and DXS Surveys (Lawrence+ 2012)II/316 : UKIDSS-DR6 Galactic Plane Survey (Lucas+ 2012)I/337 : Gaia DR1 (Gaia Collaboration, 2016)II/360 : Gaia DR2 x AllWISE catalogue (Marton+, 2019)II/364 : VIRAC. The VVV Infrared Astrometric Catalogue (Smith+, 2019)VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)J/AJ/127/1632 : UBVR(UIT) photometry of O and OB stars in SMC (Oey+, 2004)J/other/ARA+A/42.685 : Young stars near the Sun (Zuckerman+, 2004)J/A+A/492/277 : Analysis of Collinder 69 stars with VOSA (Bayo+, 2008)J/AJ/136/2413 : Galactic midplane Spitzer red sources (Robitaille+, 2008)J/ApJS/184/18 : Spitzer survey of young stellar clusters (Gutermuth+, 2009)J/ApJ/720/679 : Optical spectroscopy in Cygnus X region (Beerer+, 2010)J/ApJS/186/259 : Taurus Spitzer survey; new candidate members (Rebull+, 2010)J/ApJS/194/14 : A Pan-Carina YSO catalog (Povich+, 2011)J/ApJS/209/32 : Probable young stars in the MYStIX project (Broos+, 2013)J/ApJ/774/72 : Measurements 19 DIBs & other interstellar lines (Kos+, 2013)J/ApJS/209/29 : MYStIX; Mid-IR observations and catalogs (Kuhn+, 2013)J/ApJS/208/9 : Intrinsic colors & temperatures of PMS stars (Pecaut+, 2013)J/ApJS/209/31 : The MYStIX IR-Excess Source catalog (MIRES) (Povich+, 2013)J/MNRAS/440/2036 : VPHAS+ survey synthetic colours (Drew+, 2014)J/ApJ/787/107 : Spatial structure young stellar clusters. I. (Kuhn+, 2014)J/MNRAS/453/976 : Herbig Ae/Be X-shooter observations (Fairlamb+, 2015)J/AJ/149/64 : MIPSGAL 24{mu}m point source catalog (Gutermuth+, 2015)J/ApJ/802/60 : Structure of young stellar clusters. II. (Kuhn+, 2015)J/MNRAS/458/3479 : SVM selection of WISE YSO Candidates (Marton+, 2016)J/A+A/588/A25 : Post-AGB & CSPN evolutionary models (Miller Bertolami, 2016)J/ApJS/230/16 : 5 through L3 empirical stellar spectra SDSS (Kesseli+, 2017)J/AJ/156/241 : 1st catalog variable stars measured by ATLAS (Heinze+, 2018)J/ApJ/868/43 : AO images of WISE YSO candidates (Silverberg+, 2018)J/A+A/620/A128 : Gaia DR2 study of Herbig Ae/Be stars (Vioque+, 2018)J/A+A/620/A172 : Solar neighbourhood young stars 3D mapping (Zari+, 2018)J/MNRAS/483/5077 : Machine learning to identify symbiotic stars (Akras+, 2019)J/A+A/626/A80 : Census RhoOph candidate members Gaia DR2 (Canovas+, 2019)J/A+A/625/A135 : Galactic inters. dust Gaia-2MASS 3D maps (Lallement+, 2019)J/ApJ/880/9 : Spitzer obs. of YSOs in the SMOG field (Winston+, 2019)J/A+A/640/A1 : Portrait Galactic disc (Cantat-Gaudin+, 2020)J/ApJ/904/146 : Young stars in North America & Pelican Nebulae (Fang+, 2020)J/AJ/160/279 : Untangling Galaxy II. Structure within 3kpc (Kounkel+, 2020)J/ApJ/899/128 : Validated & members of NGC7000/IC5070 Complex (Kuhn+, 2020)J/A+A/638/A21 : New Herbig Ae/Be and classical Be stars (Vioque+, 2020)J/MNRAS/493/234 : Herbig Ae/Be accretion & mechanisms (Wichittanakom+ 2020)J/A+A/633/A51 : Distances to molecular clouds in SFR (Zucker+, 2020)J/ApJ/917/23 : SPYGLASS. I. Mapping young stellar structures (Kerr+, 2021)J/ApJS/254/33 : Gal. midplane Spitzer/IRAC cand YSOs (SPICY) (Kuhn+, 2021)J/AJ/162/282 : Untangling Galaxy. III. Pre-main-sequence (Mcbride+, 2021)J/ApJ/930/39 : 128 new Herbig stars (Vioque+, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/165/3https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/165/3http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/165/3https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/165/3https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/165/3http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/165/3GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/165/3/table2 (Stellar properties)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/165/3/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/165/3/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/165/3/table2?GETtext/xml+votable180.050000true279.80855-3.952821110.0055555555555555566/12975 14341 14353-14354 14357 14409 14647 14670 14686 14692 14695-14696 15632 15634 15680 30247 30260 30270-30271 30604 30645 30707 30718https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/165/3?format=asciiOpticaldefaultJ/AJ/165/3/table2Stellar propertiesLum[0.07/3.35] log luminosity (1)solLumphys.luminosityfloatRad[1.1/8.9] Stellar radius (1)solRadphys.size.radiusfloate_Rad[0.2/3] Error on RadsolRadstat.errorfloatAge[0.3/25.7] Stellar age (2)Myrtime.agefloatMass[1/6.6] Stellar mass (2)solMassphys.massfloate_Mass[0.1/2] Error on MasssolMassstat.error;phys.massfloatrfitsDownload the red side FITS filemeta.ref.urlcharr-spInteractive red-side spectrum plotmeta.ref.urlcharbfitsDownload the blue side FITS filemeta.ref.urlcharb-spInteractive blue-side spectrum plotmeta.ref.urlchar_RAPosition from Paper I; Kuhn+, 2021, J/ApJS/254/33 (right ascension part)degpos.eq.ra;meta.main_DEPosition from Paper I; Kuhn+, 2021, J/ApJS/254/33 (declination part)degpos.eq.dec;meta.mainSimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSPICYSPICY star identifiermeta.id;meta.mainintSpTypeSpectral type derived from spectral analysissrc.spTypecharE_SpType[1/4] Positive error on SpTypestat.error;src.spType;stat.maxinte_SpType[0/8] Negative error on SpTypestat.error;src.spType;stat.minintTeff[4550/16700] Effective temperature derived from spectral analysisKphys.temperature.effectiveinte_Teff[40/2700] Negative error on TeffKstat.error;phys.temperature.effective;stat.minintE_Teff[60/1800] Positive error on TeffKstat.error;phys.temperature.effective;stat.maxintAv[1.31/5.77] Extinction (1)magphys.absorptionfloate_Lum[0.1/0.3] Error on LumsolLumstat.errorfloate_Age[0.3/8] Error on AgeMyrstat.error;time.agefloate_Av[0.1/0.6] Error on Avmagstat.errorfloat