Detection of HD in the atmospheres of Uranus and Neptune: a new determination of the D/H ratio *
H. Feuchtgruber 1,
E. Lellouch 2,
B. Bézard 2,
Th. Encrenaz 2,
Th. de Graauw 3 and
G.R. Davis 4
Received 30 October 1998 / Accepted 13 November 1998
Observations with the Short Wavelength Spectrometer (SWS) onboard the Infrared Space Observatory (ISO) have led to the first unambiguous detection of in the atmospheres of Uranus and Neptune, from its R(2) rotational line at m. Using S(0) and S(1) quadrupolar lines of at 28.2 and 17.0 µm as atmospheric thermometers, we derive ratios of and 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 ratio in these ices is however found to be lower than in cometary ices.
Key words: planets and satellites: general planets and satellites: individual: Neptune planets and satellites: individual: Uranus solar system: formation infrared: solar system
* 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.
Send offprint requests to: H. Feuchtgruber (email@example.com)
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© European Southern Observatory (ESO) 1999
Online publication: November 26, 1998