Identification of H_{2}O in the Tail of Comet Kohoutek (1973f).

Abstract

Spectra of the tail of comet Kohoutek have been obtained in the region 5000-7500 Â. They show clearly and fairly strongly the main progression of bands of the H20 + ion with the required alternation of band structure. Only lines expected to be strong at low rotational temperature (<100° K) are observed in the cometary bands. The spin-splitting has been resolved for those << lines ,, for which it is known to be large from laboratory data. The identification of H 2 0 + in the tail of comet Kohoutek provides the first conclusive evidence for the presence of H 2 0 in comets.