J/AJ/116/2246ivo://CDS.VizieR/J/AJ/116/2246doi:10.26093/cds/vizier.51162246CDSKingsburgh R.L.McCall M.L.2023-04-06T16:50:30Z1999-05-07T20:56:12ZCDS support team

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

cds-question@unistra.frh-ii-regionsgalaxiesspectroscopyLuminosity functions in H{alpha} have been measured for H II regions in the four dwarf galaxies UGCA 86, UGCA 92, UGCA 105, and UGC 4115 using both the traditional flux measurement method of fixed-threshold photometry (FTP) and the new method, percentage-of-peak photometry (PPP). The UGCA galaxies are members of the IC 342-Maffei 1 group. These two methods give significantly different results in galaxies in which significant numbers of peaks are associated with H II region complexes. The work demonstrates that fluxes from FTP can lead to biased luminosity functions and that PPP should, in general, be preferred. It is also shown that PPP luminosity functions are not very sensitive to atmospheric transparency, whereas those constructed from FTP can be, based on data taken under different atmospheric conditions. Results to date for six galaxies show that spirals and dwarfs have luminosity functions of similar shape, which implies that the distribution of the masses of star formation sites is largely independent of the mass, and by implication, the metallicity, of the host galaxy. As measured by PPP, the mean surface brightness of the lower luminosity H II regions grows as the one-third power of the flux grows, exactly as predicted for an ensemble in which the gas density does not vary systematically with the mass of the star cluster. For the brightest H II regions, however, the relation steepens, which implies that the most massive star clusters are formed out of the densest clouds.1998AJ....116.2246Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/116/2246CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/116/2246https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/116/2246http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/116/2246https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/116/2246https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/116/2246http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/116/2246GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/116/2246/table3 (HII regions in UGCA 86)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/116/2246/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/116/2246/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/116/2246/table3?GETtext/xml+votable180.050000true59.78893967.0988510.005555555555555556Cone search capability for table J/AJ/116/2246/table4 (HII regions in UGCA 92)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/116/2246/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/116/2246/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/116/2246/table4?GETtext/xml+votable180.050000true67.99656663.6076650.005555555555555556Cone search capability for table J/AJ/116/2246/table5 (HII regions in UGCA 105)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/116/2246/table5?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/116/2246/table5?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/116/2246/table5?GETtext/xml+votable180.050000true78.49585662.592470.005555555555555556Cone search capability for table J/AJ/116/2246/table6 (HII regions in UGC 4115)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/116/2246/table6?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/116/2246/table6?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/116/2246/table6?GETtext/xml+votable180.050000true119.16038914.3458330.0055555555555555566/2031 3381 3483 4650https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/116/2246?format=asciiOpticaldefaultJ/AJ/116/2246/table3HII regions in UGCA 86recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGalaxyGalaxy namemeta.id.part;meta.mainchar[KM98]HII region number in the galaxy (1)meta.id.part;meta.mainint[HM95]? Hodge & Miller (1995ApJ...451..176H) numbermeta.idintnullable[HM95]2? Second Hodge & Miller (1995ApJ...451..176H) numberphys.atmol.qnintnullableoRAOffset east from reference star (2)arcsecpos.eq.ra;arith.difffloatoDEOffset north from reference star (2)arcsecpos.eq.dec;arith.difffloatRadiusPPP? Radius of circle covering same area as HII region from PPP (3)arcsecphys.angSize;srcfloatnullablelogFluxPPP? logarithm of total PPP flux relative to PPP values for HII reference region (3)phot.flux;arith.ratiofloatnullableRadiusFTP? Radius of circle covering same area as HII region from FTP (3)arcsecphys.angSize;srcfloatnullablelogFluxFTP? logarithm of total FTP flux relative to PPP values for HII reference region (3)phot.flux;arith.ratiofloatnullable_RAComputed Right Ascension for Equinox: J2000degpos.eq.ra;meta.main_DEComputed Declination for Equinox: J2000degpos.eq.dec;meta.mainJ/AJ/116/2246/table4HII regions in UGCA 92recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGalaxyGalaxy namemeta.id.part;meta.mainchar[KM98]HII region number in the galaxy (1)meta.id.part;meta.mainint[HM95]? Hodge & Miller (1995ApJ...451..176H) numbermeta.idintnullable[HM95]2? Second Hodge & Miller (1995ApJ...451..176H) numberphys.atmol.qnintnullableoRAOffset east from reference star (2)arcsecpos.eq.ra;arith.difffloatoDEOffset north from reference star (2)arcsecpos.eq.dec;arith.difffloatRadiusPPP? Radius of circle covering same area as HII region from PPP (3)arcsecphys.angSize;srcfloatnullablelogFluxPPP? logarithm of total PPP flux relative to PPP values for HII reference region (3)phot.flux;arith.ratiofloatnullableRadiusFTP? Radius of circle covering same area as HII region from FTP (3)arcsecphys.angSize;srcfloatnullablelogFluxFTP? logarithm of total FTP flux relative to PPP values for HII reference region (3)phot.flux;arith.ratiofloatnullable_RAComputed Right Ascension for Equinox: J2000degpos.eq.ra;meta.main_DEComputed Declination for Equinox: J2000degpos.eq.dec;meta.mainJ/AJ/116/2246/table5HII regions in UGCA 105recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGalaxyGalaxy namemeta.id.part;meta.mainchar[KM98]HII region number in the galaxy (1)meta.id.part;meta.mainint[HM95]? Hodge & Miller (1995ApJ...451..176H) numbermeta.idintnullable[HM95]2? Second Hodge & Miller (1995ApJ...451..176H) numberphys.atmol.qnintnullableoRAOffset east from reference star (2)arcsecpos.eq.ra;arith.difffloatoDEOffset north from reference star (2)arcsecpos.eq.dec;arith.difffloatRadiusPPP? Radius of circle covering same area as HII region from PPP (3)arcsecphys.angSize;srcfloatnullablelogFluxPPP? logarithm of total PPP flux relative to PPP values for HII reference region (3)phot.flux;arith.ratiofloatnullableRadiusFTP? Radius of circle covering same area as HII region from FTP (3)arcsecphys.angSize;srcfloatnullablelogFluxFTP? logarithm of total FTP flux relative to PPP values for HII reference region (3)phot.flux;arith.ratiofloatnullable_RAComputed Right Ascension for Equinox: J2000degpos.eq.ra;meta.main_DEComputed Declination for Equinox: J2000degpos.eq.dec;meta.mainJ/AJ/116/2246/table6HII regions in UGC 4115recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGalaxyGalaxy namemeta.id.part;meta.mainchar[KM98]HII region number in the galaxy (1)meta.id.part;meta.mainint[HM95]? Hodge & Miller (1995ApJ...451..176H) numbermeta.idintnullable[HM95]2? Second Hodge & Miller (1995ApJ...451..176H) numberphys.atmol.qnintnullableoRAOffset east from reference star (2)arcsecpos.eq.ra;arith.difffloatoDEOffset north from reference star (2)arcsecpos.eq.dec;arith.difffloatRadiusPPP? Radius of circle covering same area as HII region from PPP (3)arcsecphys.angSize;srcfloatnullablelogFluxPPP? logarithm of total PPP flux relative to PPP values for HII reference region (3)phot.flux;arith.ratiofloatnullableRadiusFTP? Radius of circle covering same area as HII region from FTP (3)arcsecphys.angSize;srcfloatnullablelogFluxFTP? logarithm of total FTP flux relative to PPP values for HII reference region (3)phot.flux;arith.ratiofloatnullable_RAComputed Right Ascension for Equinox: J2000degpos.eq.ra;meta.main_DEComputed Declination for Equinox: J2000degpos.eq.dec;meta.main