Vela satellite observations of solar wind ions
| Autor: | I. B. Strong, S. J. Bame, J. R. Asbridge, A. J. Hundhausen |
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| Rok vydání: | 1967 |
| Předmět: |
Physics
Atmospheric Science Ecology Paleontology Soil Science Coronal hole Astronomy Forestry Plasma Astrophysics Aquatic Science Oceanography Vela Solar wind Geophysics Polar wind Space and Planetary Science Geochemistry and Petrology Physics::Space Physics Earth and Planetary Sciences (miscellaneous) Coronal mass ejection Magnetopause Interplanetary magnetic field Earth-Surface Processes Water Science and Technology |
| Zdroj: | Journal of Geophysical Research. 72:1979-1987 |
| ISSN: | 0148-0227 |
| Popis: | Observations of solar wind ions have been made with the electrostatic analyzers of the Vela 2 and Vela 3 satellites. Analysis of data obtained between July 1964 and July 1965 by the two Vela 2 satellites leads to the following generalizations concerning the properties of the solar wind. The solar wind velocity varies in magnitude between 280 km sec−1 and 750 km sec−1; during quiet conditions it is usually near 320 km sec−1. The variation in direction is over ∼15°. For periods as long as an hour the deviation from radial flow may be as large as 10°. When averaged over the year of observation, the flow is from ∼1½° east of the sun. The proton temperatures in a direction transverse to the bulk velocity range from 8 × 105°K down to 6 × 10³°K. The lowest temperatures measured approach the limit set by instrumental resolution; these extreme values are rarely observed. Low temperatures (typically a few times 104°K) are observed when the solar wind velocity is near the low end of its range, high temperatures when the velocity is high. On the Vela 3 satellites, measurements are made at more energy steps; hence the data contain more detailed information on the plasma properties. Two-dimensional mappings of the ion distribution functions in velocity space are obtained. These mappings reveal significant anisotropies in the random motions of the ions. A ‘tail’ of nonthermal particles is usually present; the mean random energy (or temperature) of the ions is higher in the direction of this tail than in all other directions. The average direction of this tail of particles is close to the average direction of the interplanetary magnetic field. |
| Databáze: | OpenAIRE |
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