Two-dimensional MHD simulations of the solar wind interaction with Comet Halley

Numerical simulations are performed in the framework of nonlinear two-dimensional magnetohydrodynamics to investigate the solar wind interaction with Comet Halley at 0.83 a.u. corresponding to the Vega 2 encounter. The governing equations are solved by a flux corrected transport method. For a gas (water) production rate of 10(30) molecules/sec, it was found that a weak bow shock is formed at about 0.5 million km upstream the comet nucleus while a contact surface and an inner shock are located at about 20 000 km in the subsolar direction from the nucleus. We also found an enhancement of the ion-mass density just inside the contact surface, at the position of the inner shock. The model reasonably reproduced the locations of the bow shock and the diamagnetic cavity that were observed by recent missions to Comet Halley.