Infrared spectroscopic observation of methane in Comet P/Halley
Abstract
Infrared spectroscopy of comet P/Halley covering the wavelength range including the R(1) and P(2) lines of the ν3 band of CH4 around 3.3 μm was carried out after perihelion on six nights between 1986 March 15 and April 8, with a resolution of 260 km s-1. The observed flux of the lines yields a production rate of CH4 of (0.87 to 5.2) × 1027 molecules s-1 and a CH4 abundance relative to H2O of 0.20 to 1.2% for assumed rotational temperatures of 50 to 200K. However, contamination is possible due to the unknown nature of the 3.4 μm emission feature found in the comet. The implications of the methane abundance for the theory of the origin of comets are discussed, combined with observational results for other molecules and recent models for the chemistry of interstellar clouds and the primordial solar nebula. It is pointed out that the molecular abundance in the comet is similar to that of grain mantles in low-density clouds.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- December 1988
- Bibcode:
- 1988A&A...207..174K
- Keywords:
-
- Abundance;
- Astronomical Spectroscopy;
- Halley'S Comet;
- Infrared Spectroscopy;
- Methane;
- Giotto Mission;
- Infrared Spectra;
- Molecular Clouds;
- Molecular Spectra;
- Astrophysics