Characteristics of interstellar helium observed with Prognoz 6 58.4-nm photometers

The whole set of Prognoz 6 data on He 58.4 nm obtained during September 1977 to January 1978 and collected from various positions of the earth relative to the helium cone of gravitational focusing. The whole set of parameters describing the characteristics of the helium component of LISM and its interaction with the solar environment were calculated by modeling the phenomenon and by using a quantitative estimate of quality fit. The ionization lifetime of one He atom at 1 AU was determined as 8 + or - 1.5 megaseconds, and the solar line width was found to be equal to or greater than 90 mA. The sensitivity of the He I emission pattern to the solar line width and shape is indicated. The temperature of the interstellar helium was found to lie between 11,000 and 24,000 K with a favored value of 16,000 K. Several possible explanations for the difference in temperature in the interstellar medium between He and H are considered.