J/ApJS/219/28ivo://CDS.VizieR/J/ApJS/219/28doi:10.26093/cds/vizier.22190028CDSZhang J.S.Sun L.L.Riquelme D.Henkel C.Lu D.R.Zhang Y.Wang J.Z.,Wang M.Li J.2017-09-20T05:13:48Z2015-11-10T14:30:40ZCDS support team

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

cds-question@unistra.frradio-astronomyinterstellar-mediummilky-way-galaxyThe ^18^O/^17^O isotopic ratio of oxygen is a crucial measure of the secular enrichment of the interstellar medium by ejecta from high-mass versus intermediate-mass stars. So far, however, there is a lack of data, particularly from the Galactic center (GC) region. Therefore, we have mapped typical molecular clouds in this region in the J=1-0 lines of C^18^O and C^17^O with the Delingha 13.7m telescope (DLH). Complementary pointed observations toward selected positions throughout the GC region were obtained with the IRAM 30m and Mopra 22m telescopes. C^18^O/C^17^O abundance ratios reflecting the ^18^O/^17^O isotope ratios were obtained from integrated intensity ratios of C^18^O and C^17^O. For the first time, C^18^O/C^17^O abundance ratios are determined for Sgr C (V~-58km/s), Sgr D (V~80km/s), and the 1.3{deg} complex (V~80km/s). Through our mapping observations, abundance ratios are also obtained for Sgr A (~0 and ~50km/s component) and Sgr B2 (~60km/s), which are consistent with the results from previous single-point observations. Our frequency-corrected abundance ratios of the GC clouds range from 2.58+/-0.07 (Sgr D, V~80km/s, DLH) to 3.54+/-0.12 (Sgr A, ~50km/s). In addition, strong narrow components (line width less than 5km/s) from the foreground clouds are detected toward Sgr D (-18km/s), the 1.3{deg} complex (-18km/s), and M+5.3-0.3 (22km/s), with a larger abundance ratio around 4.0. Our results show a clear trend of lower C^18^O/C^17^O abundance ratios toward the GC region relative to molecular clouds in the Galactic disk. Furthermore, even inside the GC region, ratios appear not to be uniform. The low GC values are consistent with an inside-out formation scenario for our Galaxy.2015ApJS..219...28Zhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/219/28CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/559/A47 : Sgr B2(N) and Sgr B2(M) IRAM 30m line survey (Belloche+, 2013)J/PASJ/62/557 : CO clouds in the Galactic Center from NANTEN (Takeuchi+, 2010)J/A+A/430/549 : C^18^O/C^17^O near rho Oph (Wouterloot+, 2005)J/ApJS/117/427 : Sgr B2 spectral survey (Nummelin+, 1998)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/219/28https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJS/219/28http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJS/219/28https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJS/219/28https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJS/219/28http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJS/219/28GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJS/219/28/table3 (Integrated intensities and relative abundance ratios of the mapped regions)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/219/28/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/219/28/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/219/28/table3?GETtext/xml+votable180.050000true266.4379611-29.11296790.005555555555555556Cone search capability for table J/ApJS/219/28/table2 (Measured values of ^18^O/^17^O)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/219/28/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/219/28/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/219/28/table2?GETtext/xml+votable180.050000true266.41891-29.004520.0055555555555555566/28827 28830 28831 28912https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJS/219/28?format=asciiRadiodefaultJ/ApJS/219/28/table3Integrated intensities and relative abundance ratios of the mapped regionsRegRegion identifier (1)meta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintVel[-18/80]? Approximate component velocity of the regionkm/sphys.veloc;pos.heliocentricintnullableoGLONGalactic longitude offset (2)arcminpos;arith.difffloatoGLATGalactic latitude offset (2)arcminpos;arith.difffloatC18O[5.8/54.2] Integrated C^18^O intensityK.km/sphot.flux.density;em.radiofloate_C18O[0.3/3.5] Standard deviation in C18OK.km/sstat.errorfloatC17O[1.1/21.5] Integrated C^17^O intensityK.km/sphot.flux.density;em.radiofloate_C17O[0.1/1.5] Standard deviation in C17OK.km/sstat.errorfloatRatio[1.7/5.8] Integrated C^18^O/C^17^O intensity ratiospect.line.intensity;arith.ratiofloate_Ratio[0.1/1.6] Standard deviation in Ratiostat.error;arith.ratiofloat_GlonPositions computed from oGLON and OGLAT relative to (0,0) positions of each regions detailed in Note (2) (longitude part)degpos.galactic.lon_GlatPositions computed from oGLON and OGLAT relative to (0,0) positions of each regions detailed in Note (2) (latitude part)degpos.galactic.lat_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/ApJS/219/28/table2Measured values of ^18^O/^17^OrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRegRegion identifiermeta.id;meta.maincharINumber of integrated intensities measured in this regionmeta.numberintnullableInstInstrument (1)meta.id;instrcharGLON[-0.6/5.5]? Galactic longitudedegpos.galactic.lonnullableGLAT[-0.4/0.07]? Galactic latitudedegpos.galactic.latnullableu_V18c[~] Uncertainty flag on V18cmeta.code.errorcharV18cC^18^O velocity (or lower range)km/sspect.dopplerVelocintV18c2[80]? upper range of V18ckm/sspect.dopplerVelocintnullableu_W18c[~] Uncertainty flag on W18cmeta.code.errorcharW18cLine width of the C^18^O J=1-0 (or lower range)km/sspect.line.widthfloatW18c2[30/50]? Upper range of W18ckm/sspect.line.widthintnullableu_V17c[~] Uncertainty flag on V17cmeta.code.errorcharV17cC^17^O velocity (or lower range)km/sspect.dopplerVelocintV17c2[80]? Upper range of V17ckm/sspect.dopplerVelocintnullableu_W17c[~] Uncertainty flag on W17cmeta.code.errorcharW17cLine width of the C^17^O J=1-0 (or lower range)km/sspect.line.widthfloatW17c2[30/50]? Upper range of W17ckm/sspect.line.widthintnullableN[7/58]? Numbers of positions in each map (2)meta.numberintnullableC18/C17a[2.4/3.7]? Integrated intensity ratio C^18^O/C^17^O (3)spect.line.intensity;arith.ratiofloatnullablee_C18/C17a[0.1/0.5]? C18/C17a uncertaintystat.errorfloatnullableC18/C17m[2.4/4.7]? Mean C^18^O/C^17^O ratio (4)spect.line.intensity;arith.ratiofloatnullablee_C18/C17m[0.07/0.2]? C18/C17m uncertaintystat.errorfloatnullableRcor[2.5/4.9] Frequency-corrected abundance ratios were deduced from those mean values (5)spect.line.intensity;arith.ratiofloate_Rcor[0.08/0.6] Uncertainty on Rcorstat.errorfloatSimbadSimbad column added by the CDSmeta.ref.urlchar_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