Physical properties of comet 81P Wild 2

Abstract

81P/Wild 2 is the STARDUST space mission target. This comet was selected because of its newness as a Jupiter family comet and because of the discovery of a trajectory offering a low encounter velocity of only 6.1 km·s^−1. Observations over a wide range of heliocentric distances since 1987 have enable us the greatly enhance our knowledge of 81P/Wild 2, as required to mount a successful space mission. We want to present four sets of observations of comet 81P/Wild 2 which were made in order to search for rotational period of the nucleus during November 11–12, 1996, June 26–28, 1998, September 26–28, 1998 and August 12–17, 1999 using the University of Hawaii 2.2 m telescope. At the time of the observations, the comet was at heliocentric distances, r = 2.28, 3.61, 4.01 and 4.98 AU. The comet was active for all runs, and during 1996 November the coma extended >100″ (1.65×10 5 km at the distance of the comet) at PA≈262°, and during 1998 June the coma extended >51″ (1.34×10^5 km at the distance of the comet) at PA≈254°, and during 1998 September the coma extended >12″ (3.50×10^5 km at the distance of the comet) at PA≈125°, and during 1999 August the coma extended >8″ (2.90×10^4 km at the distance of the comet) at PA≈203°. Using a phase-dispersion minimization technique, we will try to find a possible rotation period.