Solar Wind Gases Research Articles

Solar wind heating beyond 1 AU

The effect of an interplanetary atomic hydrogen gas on solar wind proton, electron and α-particle temperatures beyond 1 AU is considered. It is shown that the proton temperature (and probably also the α-particle temperature) reaches a minimum between 2 AU and 4 AU, depending on values chosen for solar wind and interstellar gas parameters. Heating of the electron gas depends primarily on the thermal coupling of the protons and electrons. For strong coupling (whenT p ≳T e ), the electron temperature reaches a minimum between 4 AU and 8 AU, but for weak coupling (Coulomb collisions only), the electron temperature continues to decrease throughout the inner solar system. A spacecraft travelling to Jupiter should be able to observe the heating effect of the solar wind-interplanetary hydrogen interaction, and from such observations it may be possible of infer some properties of the interstellar neutral gas.

Distribution of gases within Apollo 15 samples: Implications for the incorporation of gases within solid bodies of the solar system

The distribution of helium, neon, and argon isotopes within Apollo 15 samples results primarily from fractionated solar wind gases, accompanied by small quantities of cosmogenic gases. No unequivocal primordial lunar gases have been detected within various mineral, rock, or glass fragments. A vug from 15555 contains solar wind gases that have abundance ratios similar to those found in the Apollo 12 aluminum foil experiments. A comparison of these Apollo 15 results with previous laser probe mass spectrometric measurements from the gas-rich Kapoeta and Fayetteville meteorites, as well as with analyses of the Apollo 12 and 14 samples, indicates that the mechanism of solar wind implantation, followed by subsequent fractionation of the gases by impact brecciation and heating, was primarily responsible for the incorporation of the original gas phase within solid bodies of the solar system.

Inert gases in a terra sample: measurements in six grain-size fractions and two single particles from Luna 20

The inert gases have been measured in six size fractions covering the range below 500 μm, in a single feldspathic fragment weighing 523 μg, and in an agglutinate particle weighing 465 μg. The two size fractions between 125 and 250 μm as well as 250 and 500 μm were separated into magnetic and non-magnetic portions, which were measured separately. Like the Apollo and Luna 16 fines, the terra fines represented by Luna 20 are very rich in trapped solar-wind gases, but they contain relatively less He 4 and Ne 20, which is revealed by their average He 4 Ne 20 ratio of 35 and Ne 20 Ar 36 ratio of 2.9. Obviously the terra materials are less retentive for solar-wind He and Ne than typical mare fines such as 10084. Whether this is due to the relatively small TiO 2 or the relatively large plagioclase content of the former is not resolved. ( Ar 36 Kr 84 ) trapped and ( Ar 36 Xe 132 ) trapped ratios are relatively large; the average values are 2800 and 14400, respectively. The apparent Ne 21 radiation ages of all the size fractions are in the range 209–286 × 10 6 yr; the average is 260 × 10 6 yr. This is in the range of values known for the Apollo and Luna 16 fines. The feldspathic fragment has a much greater apparent Ne c 21 age of 780 × 10 6 yr. The Ar 40-Ar 36 systematic reveals the presence of two Ar 40 components, because Ar 40 = (1.41 ± 0.076) Ar 36 + (0.490 ± 0.130) × 10 −4 (cm 3 STP/g). The Ar 40 Ar 36 slope of 1.41 is not inconsistent with an origin of the sample from a relatively old terra region.

Propagation of Hydromagnetic Waves in a Stochastic Magnetic Field

view Abstract Citations (20) References (18) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Propagation of Hydromagnetic Waves in a Stochastic Magnetic Field Valley, George C. Abstract The propagation of coherent small-amplitude hydromagnetic waves through a medium in which the magnetic field has a large-scale ordered component and a stationary random component is investigated. By neglecting third-order correlations between the random part of the wave and the stochastic field, dispersion relations which give the wavenumber as a function of frequency for the coherent part of the wave are obtained. From these dispersion relations, damping decrements are evaluated in several limits for the Alfve'n mode propagating parallel to the average field and for the fast magnetosonic mode prop agating perpendicular to the average field. In typical astrophysical systems these modes damp in 10-100 correlation lengths in a stochastic field; and since all other modes, and these modes at all other angles, undergo Landau damping, application to the solar wind and interstellar gas shows that no coherent hydromagnetic wave can propagate across the solar system or the Galaxy. Publication: The Astrophysical Journal Pub Date: September 1971 DOI: 10.1086/151080 Bibcode: 1971ApJ...168..251V full text sources ADS |

Interplanetary hydrogen and helium from cosmic dust and the solar wind

Interplanetary dust grains saturated with solar wind gases may act as sources of H and He in the inner solar system. Calculations for the density and fluxes of these gases are given in terms of the basic dust size distribution function. Owing to the lack of agreement between the different experimental data, it is not possible to fully assess the importance of this process. By using the data available, H and He densities in the ranges 8×10−7 to 6×10−3 cm−3 and 6×10−8 to 5×10−4 cm−3 can be predicted at 1 AU. Depending on the true effective area of the dust particles, the higher He densities could be adequate to explain the presence of 4He+ in the solar wind.

Solar Wind Gases, Cosmic Ray Spallation Products, and the Irradiation History

The isotopic abundances of the rare gases in the fines are found to be similar to those previously reported for gas-rich meteorites. Relative to the heavy gases, neon and helium are depleted by factors of 2.5 and 10 respectively. Accurate krypton-krypton ages for rocks 10017, 10047, 10057, and 10071 were obtained covering a range of from 47 to 509 x 10(6) years. Varying relative production rates of the krypton and xenon isotopes in these rocks suggest different irradiation conditions and a complex history for at least some of the rocks.

Propagation of the sudden commencement of July 8, 1966, to the magnetotail

A sudden magnetic field increase associated with the July 8, 1966, sudden commencement (sc) was observed by the OGO 3 satellite in the magnetotail. By use of the IMP 3 and Explorer 33 observations made by Ness and Taylor of the interplanetary shock that caused the sc, it is shown that the magnetospheric propagation of the field increase toward the tail is faster than the propagation of the interplanetary shock just outside the bow shock. Conclusions drawn include (1) that the observed magnetic field increase in the tail is unlikely to be due to an increased lateral pressure of the postshock solar wind gas from the side of the tail, and (2) that the transfer of additional polar magnetic flux to the tail due to the increase in the solar wind pressure on the front side of the magnetosphere can account for the observed tail field increase.