A Discussion on astronomy in the ultraviolet - Rocket and spacecraft studies of ultraviolet emissions from astrophysical targets

Abstract

Far-ultraviolet spectral measurements from rockets and spacecraft of a number of astrophysical targets are described. Rocket studies of Arcturus (a Boo) in 1969 provided the first observation of ground state atomic hydrogen and atomic oxygen emissions from the chromosphere of a cool star other than the Sun. More recent rocket measurements show the presence of atomic oxygen (1304 A) emissions and the absence of atomic carbon (1560 and 1657 A). New studies of this star with the Copernicus satellite have provided detailed information about the spectral shape of H Ly a and Mg n 2800 A radiation. Far u.v. spectra of the planets Venus and Jupiter were also obtained during our rocket experiments. Precision photometric measurements of emissions from several bright stars were obtained with the far u.v. spectrometer aboard the Apollo 17 spacecraft. The u.v. background was also observed by the Apollo 17 spectrometer. Apollo 17 u.v. observations showed that solar protons do not produce an atomic hydrogen atmosphere on the Moon. The alternative H 2 formation would not have been detectable. Rocket studies of Comet Kohoutek on 5.1 January 1974 U.T. showed a large atomic hydrogen cloud (Ly a 1216 A), atomic oxygen (1304 A), atomic carbon (1560 and 1657 A) and OH (3090 and 3142 A).