The Peculiarities of the Interaction of Phobos with the Solar Wind are Evidence of the Phobos Magnetic Obstacle (from Phobos-2 Data)

Abstract

Using magnetic field and plasma data acquired during "Phobos-2" mission in regions which have not been explored before, we study the solar wind interaction with Phobos. The draping magnetic field of the solar wind around Phobos appears at distances of 200-300 km from the Phobos day-side due to a density and magnetic field pile up in front of the Phobos obstacle. The nature of the interaction and the magnetic field signatures observed are consistent with the ratio of the proton skin depth to the actual size of the Phobos obstacle to the solar wind. Phobos deflects the flow of the solar wind and the subsolar stand-off distance of the deflection is about 16-17 Phobos radii. Source with equivalent magnetic moment M'=10^{15} A m^2 in Phobos leads to the development of such an obstacle to solar wind flow around Phobos. These data give a lesson for the study of the interaction of the small, magnetized object with solar wind.