J/A+A/653/A66ivo://CDS.VizieR/J/A+A/653/A66doi:10.26093/cds/vizier.36530066CDSBlake J.S.D.Fletcher L.N.Greathouse T.K.Orton G.S.Melin H.,Roman M.T.Antunano A.Donnelly P.T.Rowe-Gurney N.King O.2022-01-17T13:05:27Z2021-09-08T08:01:01ZCDS support team

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

cds-question@unistra.frsolar-systemsolar-system-planetsspectroscopyinfrared-astronomyThe abundance of deuterium in giant planet atmospheres provides constraints on the reservoirs of ices incorporated into these worlds during their formation and evolution. Motivated by discrepancies in the measured deuterium-hydrogen ratio (D/H) on Jupiter and Saturn, we present a new measurement of the D/H ratio in methane for Saturn from ground-based measurements. We analysed a spectral cube (covering 1151-1160cm^-1^ from 6 February 2013) from the Texas Echelon Cross Echelle Spectrograph (TEXES) on NASA's Infrared Telescope Facility (IRTF) where emission lines from both methane and deuterated methane are well resolved. Our estimate of the D/H ratio in stratospheric methane, 1.65(-0.21/+0.27)*10^-5^ is in agreement with results derived from Cassini CIRS and ISO/SWS observations, confirming the unexpectedly low CH3D abundance. Assuming a fractionation factor of 1.34(+/-0.19) we derive a hydrogen D/H of 1.23(-0.23/+0.27)*10^-5^. This value remains lower than previous tropospheric hydrogen D/H measurements of (i) Saturn 2.10(+/-0.13)*10^-5^, (ii) Jupiter 2.6(+/-0.7)*10^-5^ and (iii) the proto-solar hydrogen D/H of 2.1(+/-0.5)*10^-5^, suggesting that the fractionation factor may not be appropriate for stratospheric methane, or that the D/H ratio in Saturn's stratosphere is not representative of the bulk of the planet.2021A&A...653A..66Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/653/A66CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/653/A66https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/653/A66http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/653/A66https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/653/A66https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/653/A66http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/653/A66GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapAssociated datahttps://cdsarc.cds.unistra.fr/assocdata/?obs_collection=J/A+A/653/A66InfrareddefaultJ/A+A/653/A66/listList of fits filesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNxNumber of pixels along X-axismeta.numberintNyNumber of pixels along Y-axismeta.numberintNz? Number of pixels along Z-axismeta.numberintnullablesizeSize of FITS fileKibytephys.size;meta.fitsintFileNameName of FITS file, in subdirectory fitsmeta.id;meta.fitscharTitleTitle of the FITS filemeta.title;meta.fitschar