J/A+A/669/L15ivo://CDS.VizieR/J/A+A/669/L15doi:10.26093/cds/vizier.36699015CDSLis D.C.Goldsmith P.F.Guesten R.Schilke P.Wiesemeyer H.Seo Y.,Werner M.W.2024-11-06T20:02:22Z2023-01-18T09:06:36ZCDS support team

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

cds-question@unistra.frmolecular-cloudschemical-abundancesinfrared-astronomyspectroscopyA substantial fraction of oxygen in diffuse clouds is unaccounted for by observations and is postulated to be in an unknown refractory form, referred to as unidentified depleted oxygen (UDO), which, depending on the local gas density, may contribute up to 50% of the total oxygen content. Previous Infrared Space Observatory (ISO) observations suggest that a significant fraction of oxygen in even denser, translucent clouds may be in atomic form. We have analyzed velocity-resolved archival SOFIA observations of the 63um fine-structure [OI] transition toward the high-mass star-forming region Sgr B2(M) in the Central Molecular Zone. The foreground spiral-arm clouds as well as the extended Sgr B2 envelope between the Sun and the background dust continuum source produce multiple [OI] absorption components, spectrally separated in velocity space. The gas-phase atomic oxygen column density in foreground clouds toward Sgr B2 is well correlated with the total hydrogen column density, with an average atomic oxygen abundance of (2.51+/-0.69)x10^-4^ with respect to hydrogen nuclei. This value is in good agreement with the earlier ISO measurements on the same line of sight, and is about 35% lower than the total interstellar medium oxygen abundance in the low-density warm gas, as measured in the UV. We find no evidence that a significant fraction of the oxygen on the line of sight toward Sagittarius B2 is in the form of UDO.2023A&A...669L..15Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/669/L15CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/669/L15https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/669/L15http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/669/L15https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/669/L15https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/669/L15http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/669/L15GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapInfrareddefaultJ/A+A/669/L15/cden-oAtomic oxygen abundances and column densities (Fig. 2)VlsrLSR velocitykm/sphys.veloc;pos.lsrfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintX(OI)Atomic oxygen abundance wrt Hphys.abunddoublee_X(OI)Lower uncertainty (-1 sigma) on X(OI)stat.errordoubleE_X(OI)Upper uncertainty (+1 sigma) on X(OI)stat.error;stat.maxdoubledN(OI)/dvAtomic oxygen column densitycm**-2.km**-1.s**-1phys.columnDensitydoublee_dN(OI)/dvLower uncertainty (-1 sigma) on dN(OI)/dvcm**-2.km**-1.s**-1stat.errordoubleE_dN(OI)/dvUpper uncertainty (+1 sigma) on dN(OI)/dvcm**-2.km**-1.s**-1stat.error;stat.maxdoubleJ/A+A/669/L15/cden-hHydrogen nucleus column densities (Fig. B3)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintVlsrLSR velocitykm/sphys.veloc;pos.lsrfloatdNtot/dv? Total H nucleus column density (1)cm**-2.km**-1.s**-1phys.columnDensitydoublenullablee_dNtot/dvLower uncertainty (-1 sigma) on dNtot/dvcm**-2.km**-1.s**-1stat.errordoubleE_dNtot/dvUpper uncertainty (+1 sigma) on dNtot/dvcm**-2.km**-1.s**-1stat.error;stat.maxdouble2dNH2/dv? Twice molecular H nucleus column densitycm**-2.km**-1.s**-1phys.columnDensitydoublenullablee_2dNH2/dv? Lower uncertainty (-1 sigma) on 2dNH2/dvcm**-2.km**-1.s**-1stat.errordoublenullableE_2dNH2/dv? Upper uncertainty (+1 sigma) on 2dNH2/dvcm**-2.km**-1.s**-1stat.error;stat.maxdoublenullabledNH/dvAtomic H nucleus column densitycm**-2.km**-1.s**-1phys.columnDensitydoublee_dNH/dvLower uncertainty (-1 sigma) on dNH/dvcm**-2.km**-1.s**-1stat.errordoubleE_dNH/dvUpper uncertainty (+1 sigma) on dNH/dvcm**-2.km**-1.s**-1stat.error;stat.maxdouble