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Catalogue POP – Notice individuelle de publication

Pierel J. D. R., Nixon Conor A., Lellouch Emmanuel, Fletcher Leigh N., Bjoraker Gordon L., Achterberg Richard K., Bézard Bruno, Hesman B. E., Irwin Patrick G. J., Flasar F. M.

D/H Ratios on Saturn and Jupiter from Cassini CIRS

The Astronomical Journal, 2017, vol. 154

Référence DOI : 10.3847/1538-3881/aa899d
Référence ADS : 2017AJ....154..178P

Résumé :

We present new measurements of the deuterium abundance on Jupiter and Saturn, showing evidence that Saturn's atmosphere contains less deuterium than Jupiter's. We analyzed far-infrared spectra from the Cassini Composite Infrared Spectrometer to measure the abundance of HD on both giant planets. Our estimate of the Jovian D/H = (2.95 ± 0.55) × 10<SUP>-5</SUP> is in agreement with previous measurements by ISO/SWS: (2.25 ± 0.35) × 10<SUP>-5</SUP>, and the Galileo probe: (2.6 ± 0.7) × 10<SUP>-5</SUP>. In contrast, our estimate of the Saturn value of (2.10 ± 0.13) × 10<SUP>-5</SUP> is somewhat lower than on Jupiter (by a factor of {0.71}<SUB>-0.15</SUB><SUP> 0.22</SUP>), contrary to model predictions of a higher ratio: Saturn/Jupiter = 1.05-1.20. The Saturn D/H value is consistent with estimates for hydrogen in the protosolar nebula (2.1 ± 0.5) × 10<SUP>-5</SUP>, but its apparent divergence from the Jovian value suggests that our understanding of planetary formation and evolution is incomplete, which is in agreement with previous work.

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