Hybrid simulations of solar wind interaction with magnetized asteroids: General characteristics of the interaction region

An asteroid's global magnetic field strength, if any, is expected to be considerably weaker than magnetized planets. As a result, the interaction between the solar wind and a magnetized asteroid results in an environment which is quite distinct from planetary magnetospheres. The nature of this interaction has been investigated in the past in the context of fluid theory. However, because the size of the interaction region is comparable or even smaller than ion spatial scales, it is important that ion kinetic effects be included in studies of asteroids magnetosphere. Here, we present results of hybrid (fluid electrons, particle ions) simulations of solar wind interaction with a magnetized asteroid for a variety of solar wind conditions and magnetic dipole strength. While the nature and strength of the interaction varies considerably with change in parameters general characteristics of the interaction include the formation of a bow wave/wake and a plasma cavity tail. While the MAG instrument onboard NEAR-Shoemaker spacecraft did not detect any signals that could be attributed to 433 Eros magnetization, spacecraft flybys of other asteroids have detected magnetic signals that have been attributed to a whistler bow wave.