Astronomy and Astrophysics – Astrophysics
Scientific paper
Mar 1977
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1977a%26a....55..211m&link_type=abstract
Astronomy and Astrophysics, vol. 55, no. 2, Mar. 1977, p. 211-219
Astronomy and Astrophysics
Astrophysics
38
Helium Atoms, Hydrogen Atoms, Interstellar Gas, Optical Properties, Atmospheric Ionization, Line Spectra, Resonance Scattering
Scientific paper
A model for resonant scattering of sunlight by the nearby interstellar gas is developed which takes into account the modification of a Maxwell-Boltzmann velocity distribution by a central force. While the formalism applies to both hydrogen and helium, the latter is emphasized. Theoretical line profiles and integrated emission rates for helium are compared with those of approximate models and with existing observations. As a result of this analysis, an upward revision of the bulk flow velocity of interstellar helium relative to the solar system, previously deduced from He 584-A observations, is required. Velocities of 15-20 km/s, temperatures of the order of 5000-10,000 K, and densities of the order of 0.008-0.02 per cu cm are sufficient to explain the (helium) observations. However, higher-precision measurements are required in order to place more stringent limits on the gas parameters. Calculations of the flux of interstellar helium atoms impinging on earth's upper atmosphere show that the resulting impact ionization is small compared with terrestrial processes.
No associations
LandOfFree
Some optical and kinetic properties of the nearby interstellar gas does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Some optical and kinetic properties of the nearby interstellar gas, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Some optical and kinetic properties of the nearby interstellar gas will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1845105