J/ApJ/943/137ivo://CDS.VizieR/J/ApJ/943/137doi:10.26093/cds/vizier.19430137CDSYasui C.Kobayashi N.Saito M.Izumi N.Ikeda Y.2025-03-03T20:11:13Z2025-01-17T11:43:04ZCDS support team

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

cds-question@unistra.frh-ii-regionsinfrared-photometryopen-star-clustersWe present deep near-infrared (NIR) imaging of Sh 2-209 (S209), a low-metallicity ([O/H]=-0.5dex) HII region in the Galaxy. From the NIR images, combined with astrometric data from Gaia EDR3, we estimate the distance to S209 to be 2.5kpc. This is close enough to enable us to resolve cluster members clearly (~1000 au separation) down to a mass-detection limit of ~0.1M_{sun}_, and we have identified two star-forming clusters in S209, with individual cluster scales ~1pc. We employ a set of model luminosity functions to derive the underlying initial mass functions (IMFs) and ages for both clusters. The IMFs we obtained for both clusters exhibit slightly flat high-mass slopes ({Gamma}~-1.0) compared to the Salpeter IMF ({Gamma}=-1.35), and their break mass of ~0.1M_{sun}_ is lower than those generally seen in the solar neighborhood (~0.3M_{sun}_). In particular, because the S209 main cluster is a star-forming cluster with a larger number of members (~1500) than the number (~100) in regions previously studied in such environments, it is possible for the first time to derive the IMF in a low-metallicity environment with high accuracy over the wide mass range of 0.1-20M_{sun}_.2023ApJ...943..137Yhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/943/137CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVII/20 : Catalogue of HII Regions (Sharpless 1959)VII/50 : CO Radial Velocities Toward Galactic H II Regions (Blitz+ 1982)VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)VI/102 : Geneva stellar evolution tracks and isochrones (Lejeune+, 2001)II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)I/350 : Gaia EDR3 (Gaia Collaboration, 2020)J/AJ/113/1733 : Orion Nebula Cluster population (Hillenbrand 1997)J/A+A/337/403 : Low-mass stars evolutionary models (Baraffe+ 1998)J/ApJ/540/1016 : K-band & NICMOS phot. of Trapezium Cluster (Luhman+, 2000)J/ApJ/573/366 : Infrared photometry of Trapezium cluster (Muench+, 2002)J/A+A/404/223 : 2MASS IR star clusters in the Galaxy (Bica+, 2003)J/ApJS/161/361 : Millimeter continuum survey for protoclusters (Klein+, 2005)J/MNRAS/373/781 : JHK photometry of faint standard stars (Leggett+, 2006)J/ApJ/653/1226 : Physical properties of galactic HII regions (Quireza+, 2006)J/ApJS/162/346 : Abundance gradients in the Galaxy (Rudolph+, 2006)J/ApJ/738/27 : Galactic HII regions RRL and continuum data (Balser+, 2011)J/AJ/150/147 : Galactic HII regions. I. Stellar distances (Foster+, 2015)J/other/Sci/359.69 : Massive stars in 30 Dor (Schneider+, 2018)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/943/137https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/943/137http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/943/137https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/943/137https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/943/137http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/943/137GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/943/137/table10 (Subaru/MOIRCS Sh2-209 catalog)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/943/137/table10?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/943/137/table10?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/943/137/table10?GETtext/xml+votable180.050000true62.68342551.156903060.0055555555555555566/19308.658921184317141e-20 1.6917258414975304e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/943/137?format=asciiInfrareddefaultJ/ApJ/943/137/table10Subaru/MOIRCS Sh2-209 catalogrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeq[1/8236] Sequential identifiermeta.id;meta.mainintRAJ2000[62.68/62.88] Right Ascension (J2000) (1)degpos.eq.ra;meta.mainDEJ2000[51.10/51.22] Declination (J2000) (1)degpos.eq.dec;meta.mainJmag[11.35/22.03]? Subaru/MOIRCS J band magnitudemagphot.mag;em.IR.Jfloatnullablee_Jmag[0/0.2]? Uncertainty in Jmagmagstat.error;phot.mag;em.IR.JfloatnullableHmag[11.54/22.17]? Subaru/MOIRCS H band magnitudemagphot.mag;em.IR.Hfloatnullablee_Hmag[0/0.2]? Uncertainty in Hmagmagstat.error;phot.mag;em.IR.HfloatnullableKsmag[11.38/23.56]? Subaru/MOIRCS Ks band magnitudemagphot.mag;em.IR.Kfloatnullablee_Ksmag[0/0.2]? Uncertainty in Ksmagmagstat.error;phot.mag;em.IR.KfloatnullableYClNotes (2)meta.code.memberchar