Searching for Comets Encountering Jupiter: First Campaign

Abstract

This paper reports results from a first search for previously undetected comets in the vicinity of Jupiter. Combining these with a model for the probability for finding a comet in this region we estimate the total number of comets in the Jupiter family. Thirty-six Schmidt plates were obtained at ESO in March and April 1992. We searched the plates down to a limiting nuclear B-magnitude of 13.8. No comet was found. This result, together with a model for the probability of finding a comet close to Jupiter, yields an upper estimate of the number of objects in the Jupiter family. If we assume that the comets are inactive at ∼5 AU from the Sun, we get a conservative estimate of N ( H B N < 13.8) < 210. We discuss the possible brightening due to activity and present estimates including this effect. By assuming a certain magnitude distribution, we then compare our results with previous attempts to estimate the total size of the Jupiter family. Although our estimates are still higher than previous values, our results are independent of the distribution of comets with perihelion distance. Ongoing and future searches with the same technique will further constrain the population size of the Jupiter family.