J/ApJ/707/1417ivo://CDS.VizieR/J/ApJ/707/1417doi:10.26093/cds/vizier.17071417CDSVaidya K.Chu Y.-H.Gruendl R.A.Chen C.-H.R.Looney L.W.2026-05-19T14:24:40Z2012-02-01T11:09:38ZCDS support team

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

cds-question@unistra.frh-ii-regionsmagellanic-cloudsmolecular-cloudsWe have used archival Hubble Space Telecope (HST) H{alpha} images to study the immediate environments of massive and intermediate-mass young stellar object (YSO) candidates in the Large Magellanic Cloud (LMC). The sample of YSO candidates, taken from Gruendl & Chu (2009, Cat. J/ApJS/184/172), was selected based on Spitzer IRAC and MIPS observations of the entire LMC and complementary ground-based optical and near-infrared observations. We found HST H{alpha} images for 99 YSO candidates in the LMC, of which 82 appear to be genuine YSOs. More than 95% of the YSOs are found to be associated with molecular clouds. YSOs are seen in three different kinds of environments in the H{alpha} images: in dark clouds, inside or on the tip of bright-rimmed dust pillars, and in small HII regions. Comparisons of spectral energy distributions for YSOs in these three different kinds of environments suggest that YSOs in dark clouds are the youngest, YSOs with small HII regions are the most evolved, and YSOs in bright-rimmed dust pillars span a range of intermediate evolutionary stages. This rough evolutionary sequence is substantiated by the presence of silicate absorption features in the Spitzer Infrared Spectrograph spectra of some YSOs in dark clouds and in bright-rimmed dust pillars, but not those of YSOs in small HII regions. We present a discussion on triggered star formation for YSOs in bright-rimmed dust pillars or in dark clouds adjacent to HII regions. As many as 50% of the YSOs are resolved into multiple sources in high-resolution HST images.2009ApJ...707.1417Vhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/707/1417CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVII/232 : Nebulae in the Magellanic Clouds (Davies+ 1976)J/A+A/518/L73 : Youngest massive protostars in the LMC (Sewilo+, 2010)J/ApJS/184/172 : High- and intermediate-mass YSOs in the LMC (Gruendl+, 2009)J/ApJ/699/150 : Spectral classifications of Massive YSOs in LMC (Seale+, 2009)J/ApJS/184/1 : Molecular clouds in the LMC by NANTEN. II. (Kawamura+, 2009)J/ApJ/695/511 : Young massive stars in LHA 120-N 44 (Chen+, 2009)J/ApJS/178/56 : CO observations of LMC Giant Molecular clouds (Fukui+, 2008)J/AJ/136/18 : LMC SAGE. New candidate YSOs (Whitney+, 2008)J/PASJ/53/971 : CO catalog of LMC molecular clouds (Mizuno+, 2001)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/707/1417https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/707/1417http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/707/1417https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/707/1417https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/707/1417http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/707/1417GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/707/1417/table1 (Properties of YSOs with HST H{alpha} images)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/707/1417/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/707/1417/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/707/1417/table1?GETtext/xml+votable180.050000true74.1082917-66.53208330.005555555555555556Cone search capability for table J/ApJ/707/1417/table4 (List of non-YSOs)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/707/1417/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/707/1417/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/707/1417/table4?GETtext/xml+votable180.050000true74.1962917-66.41641670.0055555555555555566/33079 33092 33094 33098 33101-33102 33116 33126https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/707/1417?format=asciiOpticaldefaultJ/ApJ/707/1417/table1Properties of YSOs with HST H{alpha} imagesSimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeqRunning sequence numbermeta.id;meta.mainint[GC2009]Identification from Gruendl & Chu, 2009, Cat. J/ApJS/184/172 (JHHMMSS.ss+DDMMSS.s)meta.idcharprimaryHIISimbad column added by the CDSmeta.ref.urlcharCatCategory of the environment (G1)meta.codecharf_Cat[cd, ] Flag(s) on Cat (1)meta.codecharDEMAssociated HII region from Davies et al. (1976, Cat. VII/232; <DEM L NNNa> in Simbad)meta.id.assoccharLHA120Associated HII region from Henize (2)meta.id.assoccharCO?[Yes/No ] CO detection (3)meta.codecharLHNearby OB association (4)meta.id.assoccharIRSSpitzer/IRS classification of the YSO (G2)meta.codecharSi?[Yes/No ] Si absorption feature in IRS spectrameta.codecharYSOYSO typesrc.classcharFigFigure number in the papermeta.idchar_RAPosition, from the [GC2009] name (right ascension part)degpos.eq.ra;meta.main_DEPosition, from the [GC2009] name (declination part)degpos.eq.dec;meta.mainJ/ApJ/707/1417/table2Properties of resolved HII regions associated with massive YSOsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint[GC2009]YSO identification (JHHMMSS.ss+DDMMSS.s)meta.id;meta.maincharLgthLength (1)pcpos.distance;phys.sizefloatFHaH{alpha} flux not corrected for extinctionmW.m**-2phot.flux;em.line.HalphadoubleEMEmission measure of the HII regionpc.cm**-6phys.emissMeasure;obs.fielddoublenerms electron densitycm**-3stat.stdev;phys.density;phys.electronintLHaH{alpha} luminosity (2)1e-07Wphys.luminosity;em.line.HalphadoubleQ(H0)Ionizing power (Q(H^0^)) in photons/s (2)ph/sphys.luminositydoubleSpTMK spectral type (2)src.spTypecharIRSSpitzer/IRS classification of the YSO (G2)meta.codecharJ/ApJ/707/1417/table3Properties of marginally resolved and unresolved HII regions associated with massive YSOsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint[GC2009]YSO identification (1)meta.id;meta.maincharCatCategory of the environment (G1)meta.codecharFHaObserved H{alpha} fluxmW.m**-2phot.flux;em.line.HalphadoubleFc? Expected continuum flux of the YSO in the H{alpha} passbandmW.m**-2phot.flux;em.line.HalphadoublenullableIRSSpitzer/IRS classification of the YSO (G2)meta.codecharJ/ApJ/707/1417/table4List of non-YSOsSimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeqRunning sequence numbermeta.id;meta.mainint[GC2009]Source identification (JHHMMSS.ss+DDMMSS.s)meta.idcharf_[GC2009][*] *: Object also in table 1; Seq 15 (flag added by CDS)meta.codecharTypeDescription of the sourcesrc.classchar_RAPosition, from the [GC2009] name (right ascension part)degpos.eq.ra;meta.main_DEPosition, from the [GC2009] name (declination part)degpos.eq.dec;meta.main