J/ApJ/626/887ivo://CDS.VizieR/J/ApJ/626/887doi:10.26093/cds/vizier.16260887CDSKavars D.W.Dickey J.M.McClure-Griffiths N.M.Gaensler B.M.Green A.J.2012-11-13T06:13:43Z2006-10-12T21:32:16ZCDS support team

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

cds-question@unistra.frmolecular-cloudsh-i-line-emissionradio-astronomyWe present an automated routine to search for HI self-absorption features within the Southern Galactic Plane Survey (SGPS). The data were taken with the Australia Telescope Compact Array (ATCA) and the Parkes Radio Telescope and encompass 3{deg}x105{deg} of sky in the Galactic plane. We apply our routine to this entire region and derive spin temperatures and column densities for 70 of the larger HISA complexes, finding spin temperatures ranging from 6 to 41K with HI number densities of a few cm^-3^. These "missing link" clouds fill in the spin temperature and density gaps between dense molecular clouds and diffuse atomic clouds. We compare the HI emission with ^12^CO emission and find that 60% of detected HI self-absorption is correlated in space and in velocity with a molecular counterpart. This is potentially due to a molecular/atomic gas transition. We also compare HI self-absorption with Galactic spiral arms and discuss the possibility of using it as a spiral arm tracer.2005ApJ...626..887Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/626/887CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/MNRAS/201/495 : HI Survey of Southern Galactic Plane (Strong+ 1982)http://www.atnf.csiro.au/research/HI/common : SGPS Home Pagehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/626/887https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/626/887http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/626/887https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/626/887https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/626/887http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/626/887GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/626/887/table2 (Computed Properties for 70 HISA Features)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/626/887/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/626/887/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/626/887/table2?GETtext/xml+votable180.050000true127.1559-39.45130.0055555555555555566/37366 37367 37373 37374 37757 37844 37846 37848 37854 37873 37875 37884 37886 37907 37924 37931 38024 38026 39249 39259 39279 41658 41660 41671 41674 41682 41685 41696 41766 41767 41772 41777 41780 41801 41802 41804 41814 41816 42158 42167 42171 42207 42212 42216 42228 42378 42379 42380 42386 42390 42391 42396 42496 42499 42500 42501 43015https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/626/887?format=asciiRadiodefaultJ/ApJ/626/887/table2Computed Properties for 70 HISA FeaturesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint[KDM2005]Sequential numbermeta.recordintGLONGalactic longitudedegpos.galactic.lonGLATGalactic latitudedegpos.galactic.latRVRadial velocity (1)km/sphys.veloc;pos.heliocentricfloatl_DistUpper limit flag on distance estimatemeta.code.errorcharDistNear kinematic distancekpcpos.distancefloatdLinear size of the cloudpcphys.sizefloatTS(1)Spin temperature for {tau}=1Kphys.temperature;phys.electronintTS(inf)Spin temperature for {tau}={infinity}Kphys.temperature;phys.electronintDnuEquivalent width of the linekm/sspect.line.eqWidthfloatNHIHI column density1e+19cm**-2phys.columnDensityfloatnHIHI lower limit density valuecm**-3phys.densityfloat_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.decnullableindexed