Position and structure of the comet Halley bow shock: Vega‐ 1 and Vega‐2 measurements

Abstract

The effect of solar wind loading by cometary ions on the position and structure of the comet Halley bow shock is discussed on the basis of simultaneous measurements of plasma, magnetic field and plasma waves aboard the "Vega‐1" and "Vega‐2" spacecraft. Data from the inbound crossings of the bow shock show that both quasiperpendiuclar ("Vega‐1") and quasiparallel ("Vega‐2") shocks were observed. The thickness of these shocks is greater than that of the Earth's bow shock at least by the ratio of the masses of cometary ions and protons. The bow shock position is reasonably well described by the kinetic model of solar wind loading by cometary ions.