J/A+A/610/A9ivo://CDS.VizieR/J/A+A/610/A9doi:10.26093/cds/vizier.36100009CDSGoto M.Bailey J.D.Hocuk S.Caselli P.Esplugues G.B.Cazaux S.,Spaans M.2018-03-01T11:48:43Z2018-02-12T09:21:52ZCDS support team

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

cds-question@unistra.frmolecular-cloudsinfrared-sourcesradio-spectroscopySpectroscopic studies of ices in nearby star-forming regions indicate that ice mantles form on dust grains in two distinct steps, starting with polar ice formation (H_2_O rich) and switching to apolar ice (CO rich). We test how well the picture applies to more diffuse and quiescent clouds where the formation of the first layers of ice mantles can be witnessed. Medium-resolution near-infrared spectra are obtained toward background field stars behind the Pipe Nebula. The water ice absorption is positively detected at 3.0um in seven lines of sight out of 21 sources for which observed spectra are successfully reduced. The peak optical depth of the water ice is significantly lower than those in Taurus with the same A_V_. The source with the highest water-ice optical depth shows CO ice absorption at 4.7um as well. The fractional abundance of CO ice with respect to water ice is 16+7-6%, and about half as much as the values typically seen in low-mass star-forming regions. A small fractional abundance of CO ice is consistent with some of the existing simulations. Observations of CO2 ice in the early diffuse phase of a cloud play a decisive role in understanding the switching mechanism between polar and apolar ice formation.2018A&A...610A...9Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/610/A9CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJ/699/742 : Properties of cores in the Pipe Nebula (Rathborne+, 2009)J/ApJ/725/2232 : Deep NIR survey of the Pipe Nebula. II. (Roman-Zuniga+, 2010)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/610/A9https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/610/A9http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/610/A9https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/610/A9https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/610/A9http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/610/A9GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/610/A9/list (Summary of targets and optical depths of ices with spectra (extract of table1))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/610/A9/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/610/A9/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/610/A9/list?GETtext/xml+votable180.050000true262.0222917-26.45147220.0055555555555555566/28859 29200-292017.952274030004205e-20 1.0188844282367877e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/610/A9?format=asciiInfraredRadiodefaultJ/A+A/610/A9/pipe1Pipe 1 spectrumrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelengthumem.wldoubletauOptical depthphys.absorption.opticalDepthdoubleJ/A+A/610/A9/pipe2Pipe 2 spectrumrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelengthumem.wldoubletauOptical depthphys.absorption.opticalDepthdoubleJ/A+A/610/A9/pipe6Pipe 6 spectrumrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelengthumem.wldoubletauOptical depthphys.absorption.opticalDepthdoubleJ/A+A/610/A9/pipe7Pipe 7 spectrumrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelengthumem.wldoubletauOptical depthphys.absorption.opticalDepthdoubleJ/A+A/610/A9/pipe8Pipe 8 spectrumrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelengthumem.wldoubletauOptical depthphys.absorption.opticalDepthdoubleJ/A+A/610/A9/pipe14Pipe 14 spectrumrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelengthumem.wldoubletauOptical depthphys.absorption.opticalDepthdoubleJ/A+A/610/A9/pipe15Pipe 15 spectrumrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelengthumem.wldoubletauOptical depthphys.absorption.opticalDepthdoubleJ/A+A/610/A9/listSummary of targets and optical depths of ices with spectra (extract of table1)IDID numbermeta.id;meta.mainintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintspShow the spectrummeta.ref.urlchar2MASS2MASS designation (HHMMSSss+DDMMSSs)meta.idcharKsmagKs magnitudemagphot.mag;em.IR.KfloatSpTypeSpectral type (from SpeX)src.spTypecharAVceAbsorption in V band (CE) (1)magphys.absorptionfloatAKceAbsorption in K band (CE) (2)magphys.absorptionfloatAKsxAbsorption in K band (SpeX) (3)magphys.absorptionfloatAKsed? Absorption in K band (SED) (4)magphys.absorptionfloatnullabletau3.0Peak optical depth of water ice at 3.0umphys.absorption.opticalDepth;stat.maxfloatE_tau3.01{sigma} error on tau3.0 (upper value)stat.error;stat.maxfloate_tau3.01{sigma} error on tau3.0 (lower value)stat.errorfloatN(H2O)H_2_O column density1e+17cm**-2phys.columnDensityfloatE_N(H2O)Error on N(H2O) (upper value)1e+17cm**-2stat.error;stat.maxfloate_N(H2O)Error on N(H2O) (lower value)1e+17cm**-2stat.errorfloatl_tau4.7Limit flag on tau4.7 (3{sigma})meta.code.errorchartau4.7Peak optical depth of water ice at 4.7umphys.absorption.opticalDepth;stat.maxfloate_tau4.7? 1{sigma} rms uncertainty on tau4.7stat.errorfloatnullablel_N(CO)Limit flag on N(CO) (3{sigma})meta.code.errorcharN(CO)CO ice column density (5)1e+16cm**-2phys.columnDensityfloate_N(CO)? rms uncertainty on N(CO)1e+16cm**-2stat.errorfloatnullablen_N(CO)[b] Note on N(CO) (6)meta.notecharFileNameName of the file with spectrummeta.id;meta.filechar_RAPositions from 2MASS name (right ascension part)degpos.eq.ra;meta.main_DEPositions from 2MASS name (declination part)degpos.eq.dec;meta.main