The dependence of the Martian magnetopause and bow shock on solar wind ram pressure according to Phobos 2 TAUS ion spectrometer measurements
Abstract
The location of the Martian magnetopause and that of the bow shock are studied on the basis of three-dimensional solar wind proton spectra measured by the TAUS spectrometer on board Phobos 2 in its 56 circular orbits. The clear and strong dependence of the areomagnetopause position on solar wind ram pressure was revealed, while the position of the bow shock was practically independent of this parameter. In the power law expression telling the dependence of the Martian magnetotail thickness D on the solar wind ram pressure: D~(ρv2)-1/k, the power index turned out to be k~5.9+/-0.5. The close coincidence of this index with k=6 for a dipole geomagnetic field, and the large areomagnetotail thickness compared with the planetary diameter, suggest that an intrinsic dipole magnetic field is likely to be an important factor in the solar wind interaction with Mars. On the other hand, the relatively stable position of the subsolar point of the Martian magnetopause and unambiguous induction effects observed by the Phobos 2 MAGMA magnetic experiment in the magnetotail indicate the essential role of an induced magnetic field, too. The weak dependence of the terminator bow shock position on the solar wind ram pressure may be related to the relatively stable position of the subsolar magnetopause.
- Publication:
-
Journal of Geophysical Research
- Pub Date:
- February 1993
- DOI:
- 10.1029/92JA01666
- Bibcode:
- 1993JGR....98.1303V
- Keywords:
-
- Magnetopause;
- Mars Atmosphere;
- Mass Spectrometers;
- Shock Waves;
- Solar Protons;
- Solar Wind;
- Circular Orbits;
- Geomagnetism;
- Planetary Magnetotails;
- Satellite Orbits;
- MARS;
- MAGNETOSPHERE;
- MAGNETOPAUSE;
- BOWSHOCK;
- SOLAR WIND;
- INTERACTION;
- PRESSURE;
- SPACECRAFT OBSERVATIONS;
- PHOBOS 2 MISSION;
- TAUS INSTRUMENT;
- SPECTROMETRY;
- POSITION (LOCATION);
- SPECTRA;
- PROTONS;
- MAGNETOTAIL;
- THICKNESS;
- MAGNETIC FIELD;
- MAGMA INSTRUMENT;
- ANALYSIS;
- Magnetospheric Physics: Magnetopause;
- cusp;
- and boundary layers;
- Interplanetary Physics: Planetary bow shocks;
- Magnetospheric Physics: Magnetotail