J/A+A/627/A95ivo://CDS.VizieR/J/A+A/627/A95doi:10.26093/cds/vizier.36270095CDSLiszt H.Gerin M.Grenier I.2019-07-15T11:07:44Z2019-07-05T07:54:37ZCDS support team

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

cds-question@unistra.frmolecular-cloudsradio-spectroscopyinterstellar-mediumTo determine carbon monoxide column densities along sightlines through the Chamaeleon cloud complex where molecular absorption had been observed but CO emission had not been detected. We took ^12^CO J=1-0 absorption profiles toward 6 of 8 members of a group of sightlines in Chamaeleon having abundant dark neutral matter and molecular hydrogen but no detectable CO emission. CO absorption was detected along five of the six sightlines at column densities 4x10^+13^cm^-2^<~N(CO)<~10^15^cm^-2^ that are below typical survey detection limits of 1-2K-km/s. Dark gas absent in CO emission along sightlines in the outskirts of the Chamaeleon complex where molecular gas is readily detected in HCO^+^ absorption results from small CO column densities around the onset of CO formation at the HI/H_2_ transition. Relative abundances N(CO)/H_2_<3x10^-6^ in Chamaeleon are comparable to those seen in UV absorption toward early-type stars and in a CO absorption/emission line survey toward local quasar background targets away from the Galactic plane.2019A&A...627A..95Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/627/A95CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/627/A95https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/627/A95http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/627/A95https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/627/A95https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/627/A95http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/627/A95GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/627/A95/table1 (Sightline and velocity-integrated spectral line properties)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/627/A95/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/627/A95/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/627/A95/table1?GETtext/xml+votable180.050000true9.424275-77.311158060.0055555555555555566/32897 32929 32939 33319 33413 334157.619980005854211e-23 7.619980005854211e-23https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/627/A95?format=asciiMillimeterdefaultJ/A+A/627/A95/table1Sightline and velocity-integrated spectral line propertiesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameSource namemeta.id;meta.maincharRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainGLONGalactic longitudedegpos.galactic.lonGLATGalactic latitudedegpos.galactic.latfloatE(B-V)Interstellar extinction (1)magphot.color.excessfloatNHIHI column density (2)1e+20cm**-2phys.columnDensityfloatGammaHCO+HCO^+^ integrated J=1-0 optical depthkm/sphys.absorption.opticalDepthfloate_GammaHCO+rms uncertainty on GammaHCO+km/sstat.errorfloatS115Flux density at 115GHzJyphot.flux.density;em.mm.100-200GHzfloatsigmal/cLine/continuum rms at zero optical depth in the 2x oversampled spectrumphys.absorption.opticalDepthfloatl_GammaCO3{sigma} upper limit flag on GammaCOmeta.code.errorcharGammaCOCO integrated J=1-0 optical depthkm/sphys.absorption.opticalDepthfloate_GammaCO? rms uncertainty on GammaCOkm/sstat.errorfloatnullablespShow the spectrummeta.ref.urlcharFileNameName of FITS ^12^CO J=1-0 spectrum, in subdirectory fitsmeta.idchar