Dynamical effects of comet P/Halley gas production

¹ KFKI Research Institute for Particle and Nuclear Physics, PO Box 49, 1525 Budapest, Hungary
² Service d'Aéronomie du CNRS, BP 3, 91371 Verrières le Buisson Cedex, France
³ Institute for Astronomy and Space Physics, Box 515, 752 37 Uppsala, Sweden
⁴ Central Research Institute on Machine Building (TsNIIMASCH), Pionyerskaya St., 4 Korolev, Moscow Region 141070, Russia

Corresponding author: K. Szegö, szego@rmki.kfki.hu

Received: 12 February 2001
Accepted: 7 March 2001

Abstract

We revisit the rotation of P/Halley taking into account the most essential observational constraints, as well as the external torques affecting the nucleus, in particular the outgassing torque. We solve the dirty ice sublimation equations at each point of the sunlit surface, using, for the first time, the surface shape derived from the 1986 flybys imaging data. We assume that the nuclear surface is homogeneous in composition, thus reducing the number of model free parameters to one only: the dust-to-ice ratio on the surface. Our derived rotation model is a short-axis mode; it is consistent both with the 1986 nucleus imaging data, with the estimated non gravitational force, and with the observed time variations of the nucleus production rates. The outgassing torque results in a significant variation of the angular momentum vector -for the assumed nucleus density of 0.5 g/cm³.