Detection of HD in the atmospheres of Uranus and Neptune: a new determination of the D/H ratio
Abstract
Observations with the Short Wavelength Spectrometer (SWS) onboard the Infrared Space Observatory (ISO) have led to the first unambiguous detection of HD in the atmospheres of Uranus and Neptune, from its R(2) rotational line at 37.7 mu m. Using S(0) and S(1) quadrupolar lines of H_2 at 28.2 and 17.0 mu m as atmospheric thermometers, we derive D/H ratios of 5.5({{+3.5}atop {-1.5}})*E(-5) and 6.5({{+2.5}atop {-1.5}})*E(-5) on Uranus and Neptune respectively. This confirms that compared to Jupiter and Saturn, Uranus and Neptune have been enriched in deuterium by the mixing of their atmospheres with D-rich protoplanetary ices. Assuming complete mixing of the planets, the D/H ratio in these ices is however found to be lower than in cometary ices. Based on observations made with ISO, a project of ESA with participation of ISAS and NASA, and the SWS, a joint project of SRON and MPE (DARA grants no 50 QI9402 3 and 50 QI 8610\,8) with contributions from KU Leuven, Steward Observatory and Phillips Laboratory.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- January 1999
- Bibcode:
- 1999A&A...341L..17F
- Keywords:
-
- PLANETS AND SATELLITES: GENERAL;
- PLANETS AND SATELLITES: INDIVIDUAL: NEPTUNE;
- PLANETS AND SATELLITES: INDIVIDUAL: URANUS;
- SOLAR SYSTEM: FORMATION;
- INFRARED: SOLAR SYSTEM