Neutral and ion-exospheres in the solar wind with applications to Mercury

Journal Article · Sat Dec 01 04:00:00 EST 1973 · Planet. Space Sci., v. 21, no. 12, pp. 2181-2191

DOI:https://doi.org/10.1016/0032-0633(73)90192-X· OSTI ID:4360682

Hartle, R E; Ogilvie, K W; Wu, C S

A model of planetary neutral and ion-exospheres in the solar wind is formulated for weak or lunar like solar-wind interaction with a planet. The neutral exosphere model allows for density and temperature variations and for rotation at the exobase. The ion-exosphere is produced by ionization of the neutral exosphere in the solar wind and its density distribution is obtained by solving the continuity equation in the drift approximation. Applying to Mercury a surface temperature distribution inferred from infrared data and a vanishing bound neutral flux at the base, He and He/sup +/ density distributions are found. When the He atmosphere of Mercury is due entirely to the surface bombardment by solar wind He/sup 2+/, the resulting He/sup +/ density is found to vary from l.5 x 10/sup 1/ to 10/sup -3/ cm/sup -3/ over the range 1.5 to 5 planetocentric radii on the dayside. These densities are found to be detectable by typical solarwind plasma instruments. The possible effects of cyclotronresonant scattering by interplanetary magnetic field fluctuations are examined and shown to be negligible. An electromagnetic plasma instability, triggered by the birth of ions in the exosphere, is shown to be important for the thermalization of the energy mode transverse to the interplanetary magnetic field, allowing more ions to be detected by solar-wind ion probes. (auth)

• Research Organization: Goddard Space Flight Center, Greenbelt, MD
• NSA Number: NSA-29-013561
• OSTI ID: 4360682
• Journal Information: Planet. Space Sci., v. 21, no. 12, pp. 2181-2191, Journal Name: Planet. Space Sci., v. 21, no. 12, pp. 2181-2191; ISSN PLSSA
• Country of Publication: United Kingdom
• Language: English

Related Subjects

*MERCURY PLANET-- PLANETARY ATMOSPHERES
*SOLAR WIND-- IONS
ALPHA PARTICLES
CONTINUITY EQUATIONS
DENSITY
ENERGY LOSSES
EXOSPHERE
HELIUM IONS
INTERPLANETARY SPACE
IONIZATION
MAGNETIC FIELDS
MOON
N56400* --Physics (Astrophysics & Cosmology)--Solar Phenomena
PLASMA INSTABILITY
ROTATION
SURFACES
TEMPERATURE DEPENDENCE
VARIATIONS