J/ApJ/735/75ivo://CDS.VizieR/J/ApJ/735/75doi:10.26093/cds/vizier.17350075CDSLee J.H.Hwang N.Lee M.G.2013-01-30T21:22:53Z2013-01-16T11:49:28ZCDS support team

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

cds-question@unistra.frgalaxiesvisible-astronomyh-ii-regionsWe present a study of HII regions in M51 using the Hubble Space Telescope Advanced Camera for Surveys images taken as part of the Hubble Heritage Program. We have cataloged about 19600 HII regions in M51 with H{alpha} luminosity in the range of L=10^35.5^-10^39.0^erg/s. The H{alpha} luminosity function of HII regions (HII LF) in M51 is well represented by a double power law with its index {alpha}=-2.25+/-0.02 for the bright part and {alpha}=-1.42+/-0.01 for the faint part, separated at a break point L=10^37.1^erg/s. This break was not found in previous studies of M51 HII regions. Comparison with simulated HII LFs suggests that this break is caused by the transition of HII region ionizing sources, from low-mass clusters (with ~10^3^M_{sun}_, including several OB stars) to more massive clusters (including several tens of OB stars). The HII LFs with L<10^37.1^erg/s are found to have different slopes for different parts in M51: the HII LF for the interarm region is steeper than those for the arm and the nuclear regions. This observed difference in HII LFs can be explained by evolutionary effects: HII regions in the interarm region are relatively older than those in the other parts of M51.2011ApJ...735...75Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/735/75CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/hst : HST Archived Exposures Catalog (STScI, 2007)J/AJ/141/113 : HII regions of M51 and NGC 4449 (Gutierrez+, 2011)J/ApJS/178/1 : Distribution of HII regions in disk galaxies (Sanchez+, 2008)J/MNRAS/361/1063 : Oxygen abundances of HII regions (Perez-Montero+, 2005)J/A+A/397/473 : HST photometry of M51 cluster (Bik+, 2003)J/A+AS/131/319 : HII regions catalogue (Petit+ 1998)J/A+A/309/446 : HII Regions in M51 (Petit+, 1996)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/735/75https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/735/75http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/735/75https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/735/75https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/735/75http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/735/75GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/735/75/table1 (*A catalog of M51 H II regions in the original sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/735/75/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/735/75/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/735/75/table1?GETtext/xml+votable180.050000true202.393524247.15970610.005555555555555556Cone search capability for table J/ApJ/735/75/table2 (*A catalog of M51 H II regions in the group sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/735/75/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/735/75/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/735/75/table2?GETtext/xml+votable180.050000true202.393524247.15970610.0055555555555555566/11026 11027https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/735/75?format=asciiOpticaldefaultJ/ApJ/735/75/table1*A catalog of M51 H II regions in the original samplerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeq[1/19598] Index numbermeta.id;meta.mainintRAJ2000Right Ascension in decimal degrees (J2000) (1)degpos.eq.ra;meta.mainDEJ2000Declination in decimal degrees (J2000) (1)degpos.eq.dec;meta.mainFHa[0.43/1841] H{alpha} flux (10-16erg/cm^2^/s)1e-19W.m**-2phot.flux;em.line.HalphadoublelogLHaLog of H{alpha} luminosity [erg/s] (2)log(1e-07W)phys.luminosity;em.line.HalphafloatADia[0.18/2.84] Angular diameter (3)arcsecphys.angSizefloatPDiaPhysical diameter (3)pcphys.size.diameterfloatPos[ACIN] Position in the galaxy code (G1)meta.codecharGID[10/19591]? Group sample identification numbermeta.idintnullableJ/ApJ/735/75/table2*A catalog of M51 H II regions in the group samplePosPosition in the galaxy code (G1)meta.codecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintID[1/19598] Index number ("GID" if more than one HII region in table 1, else "Seq" of table 1)meta.id;meta.mainintHIINumber of HII regions in this group (0=1)meta.numberintnullableRAJ2000Right Ascension in decimal degrees (J2000) (1)degpos.eq.ra;meta.mainDEJ2000Declination in decimal degrees (J2000) (1)degpos.eq.dec;meta.mainFHa[0.4/17412] H{alpha} flux (10-16erg/cm^2^/s) (2)1e-19W.m**-2phot.flux;em.line.HalphadoublelogLHaLog of H{alpha} luminosity [erg/s] (3)log(1e-07W)phys.luminosity;em.line.HalphafloatADia[0.18/12.01] Angular diameter (4)arcsecphys.angSizefloatPDiaPhysical diameter (4)pcphys.size.diameterfloat