J/ApJ/428/693ivo://CDS.VizieR/J/ApJ/428/693doi:10.26093/cds/vizier.14280693CDSWilliams J.P.De Geus E.J.Blitz L.2013-03-05T06:34:33Z1999-01-24T16:56:53ZCDS support team

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

cds-question@unistra.frnebulaegalaxy-classification-systemsWe describe an automatic, objective routine for analyzing the clumpy structure in a spectral line position-position-velocity data cube. The algorithm works by first contouring the data at a multiple of the rms noise of the observations, then searches for peaks of emission which locate the clumps, and then follows them down to lower intensities. No a priori clump profile is assumed. By creating simulated data, we test the performance of the algorithm and show that a contour map most accurately depicts internal structure at a contouring interval equal to twice the rms noise of the map. Blending of clump emission leads to small errors in mass and size determinations and in severe cases can result in a number of clumps being misidentified as a single unit, flattening the measured clump mass spectrum. The algorithm is applied to two real data sets as an example of its use. The Rosette molecular cloud is a "typical" star-forming cloud, but in the Maddalena molecular cloud high-mass star formation is completely absent. Comparison of the two clump lists generated by the algorithm show that on a one-to-one basis the clumps in the star-forming cloud have higher peak temperatures, higher average densities, and are more gravitationally bound than in the non star-forming cloud. Collective properties of the clumps, such as temperature-size-line-width-mass relations appear very similar, however. Contrary to the initial results reported in a previous paper (Williams & Blitz, 1993ApJ...405L..75W), we find that the current, more thoroughly tested analysis finds no significant difference in the clump mass spectrum of the two clouds.1994ApJ...428..693Whttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/428/693CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/428/693https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/428/693http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/428/693https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/428/693https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/428/693http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/428/693GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/428/693/table2 (Clumps in the Rosette molecular cloud)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/428/693/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/428/693/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/428/693/table2?GETtext/xml+votable180.050000true98.521494.440570.0055555555555555565/5560 6/22244 22246 22249https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/428/693?format=asciiOpticaldefaultJ/ApJ/428/693/table2Clumps in the Rosette molecular cloudTpeakPeak temperatureKphys.temperaturefloatDREquivalent circular radius (1)pcpos.distancefloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRMC[1/95]+ Clump number ([WDB94] RMC NN in Simbad)meta.id;meta.mainintprimaryindexedGLONPeak galactic longitudedegpos.galactic.lonGLATPeak galactic latitudedegpos.galactic.latVpeakPeak velocitykm/sphys.veloc;stat.maxfloatFWHMLine width (1)km/sspect.line.widthfloatMlteClump masses (2)solMassphys.massintMvirVirial mass (3)solMassphys.massint_RA.icrsRight ascension (ICRS) (computed by VizieR, not part of the original data)degpos.eq.ranullableindexed_DE.icrsDeclination (ICRS) (computed by VizieR, not part of the original data)degpos.eq.decnullableindexedJ/ApJ/428/693/table3aClumps in the Maddalena molecular cloud: region 1 (RA=6h46m50s, DE=-4{deg}31'14")recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMMC[1/58]+ Clump number (1)meta.id;meta.mainintprimaryindexedoRApeakOffset from right ascension (2)arcminpos.eq.ra;arith.diffintoDEpeakOffset from declination (2)arcminpos.eq.dec;arith.diffintVpeakPeak velocitykm/sphys.veloc;stat.maxfloatTpeakPeak temperatureKphys.temperaturefloatDREquivalent circular radius (3)pcpos.distancefloatFWHMLine width (3)km/sspect.line.widthfloatMlteClump masses (4)solMassphys.massintMvirVirial mass (5)solMassphys.massintJ/ApJ/428/693/table3bClumps in the Maddalena molecular cloud: region 2 (RA=6h43m39s, DE=-3{deg}30'23")recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMMC[1/58]+ Clump number (1)meta.id;meta.mainintprimaryindexedoRApeakOffset from right ascension (2)arcminpos.eq.ra;arith.diffintoDEpeakOffset from declination (2)arcminpos.eq.dec;arith.diffintVpeakPeak velocitykm/sphys.veloc;stat.maxfloatTpeakPeak temperatureKphys.temperaturefloatDREquivalent circular radius (3)pcpos.distancefloatFWHMLine width (3)km/sspect.line.widthfloatMlteClump masses (4)solMassphys.massintMvirVirial mass (5)solMassphys.massint