J/ApJ/877/154ivo://CDS.VizieR/J/ApJ/877/154doi:10.26093/cds/vizier.18770154CDSYan Y.T.Zhang J.S.Henkel C.Mufakharov T.Jia L.W.Tang X.D.,Wu Y.J.Li J.Zeng Z.A.Wang Y.X.Li Y.Q.Huang J.Jian J.M.2021-02-19T07:45:02Z2020-12-18T08:14:48ZCDS support team

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

cds-question@unistra.frmolecular-cloudsinterstellar-mediumradio-astronomyWe present observations of the C-band 1_10_-1_11_ (4.8GHz) and Ku-band 2_11_-2_12_ (14.5GHz) K-doublet lines of H_2_CO and the C-band 1_10_-1_11_ (4.6GHz) line of H_2_^13^CO toward a large sample of Galactic molecular clouds, through the Shanghai Tianma 65m radio telescope (TMRT). Our sample with 112 sources includes strong H_2_CO sources from the TMRT molecular line survey at C-band and other known H_2_CO sources. All three lines are detected toward 38 objects (43 radial velocity components) yielding a detection rate of 34%. Complementary observations of their continuum emission at both C- and Ku-bands were performed. Combining spectral line parameters and continuum data, we calculate the column densities, the optical depths and the isotope ratio H_2_^12^CO/H_2_^13^CO for each source. To evaluate photon trapping caused by sometimes significant opacities in the main isotopologue's rotational mm-wave lines connecting our measured K-doublets, and to obtain ^12^C/^13^C abundance ratios, we used the RADEX non-LTE model accounting for radiative transfer effects. This implied the use of the new collision rates from Wiesenfeld & Faure. Also implementing distance values from trigonometric parallax measurements for our sources, we obtain a linear fit of ^12^C/^13^C=(5.08+/-1.10)D_GC_+(11.86+/-6.60), with a correlation coefficient of 0.58. D_GC_ refers to Galactocentric distances. Our ^12^C/^13^C ratios agree very well with the ones deduced from CN and C^18^O but are lower than those previously reported on the basis of H_2_CO, tending to suggest that the bulk of the H_2_CO in our sources was formed on dust grain mantles and not in the gas phase.2019ApJ...877..154Yhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/877/154CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVI/51 : Collisional Excitation Rates of Formaldehyde (Green 1991)J/A+A/361/1079 : HNCO in massive galactic dense cores (Zinchenko, 2000)J/ApJS/138/63 : H_2_CO and H{alpha} observations of UC HII (Araya+, 2002)J/ApJ/587/714 : H_2_CO and H{alpha} observations of UC HII (Watson+, 2003)J/ApJS/154/553 : Inner galaxy massive star formation regions (Sewilo+, 2004)J/ApJ/699/1153 : Distances to GRS molecular clouds (Roman-Duval+, 2009)J/A+A/493/687 : Rotational excitation of formaldehyde by H2 (Faure+, 2009)J/ApJ/723/915 : Aquila star-forming region with BLAST (Rivera-Ingraham+, 2010)J/ApJ/783/130 : Parallaxes of high mass star forming regions (Reid+, 2014)J/A+A/598/A30 : Massive star forming molecular clumps Tkin (Tang+, 2017)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/877/154https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/877/154http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/877/154https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/877/154https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/877/154http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/877/154GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/877/154/table6 (H_2_^12^CO and H_2_^13^CO 1_10_-1_11_ observations of the entire sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/877/154/table6?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/877/154/table6?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/877/154/table6?GETtext/xml+votable180.050000true9.197291763.48394440.0055555555555555566/3 1340 1470 2973 3011 3061 3198 3262 3302 3309 3311 3649 4365 14241 14285 14317 14359 14594 14611 14624 14643 14692 14704 15362 15408 15414 15473 15474 15567 15627 15629 15676 15759 21439 21510 21542 22178 22179 22212 22855 23637 23764 23795 23969 24189 24325 24362 24499 24554 28830 28831 28912 29091 29092 29094 29096 29097 29101 29114 29116 29510 29517 29533 30259 30262 30269 30313 30318 30319 30328 30420 30617 30618 30622 30644 30694 30715 39895 39905 40612https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/877/154?format=asciiRadiodefaultJ/ApJ/877/154/table6H_2_^12^CO and H_2_^13^CO 1_10_-1_11_ observations of the entire samplerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameSource Namemeta.id;meta.maincharf_NameFlag on Name (1)meta.codecharRAJ2000Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of Declination (J2000)pos.eq.dec;meta.mainLineMolecular species (2)meta.id;phys.molTexp[2/438] Integration time, minutes (3)mintime.epochfloatrms[4.3/186] RMS noise obtained from Gaussian fittingmKinstr.det.noisefloatDV[0.059/0.84] Corresponding channel widthkm/sspect.line.widthfloat