A CCD portrait of Comet P/Tempel 2

Abstract

The development of activity in Comet P/Tempel 2 is studied from aphelion (R = 4 AU) to perihelion (R = 1.4 AU) using extensive time-series CCD photometry and CCD spectra. The comet undergoes a profound morphological change at R of about 2-2.5 AU, from a bare nucleus at larger distances to an active comet supporting a coma of gas and dust. Cyclic photometric variations with the period T = 8.95 + or - 0.01 hr. are present at all R, and are attributed to the rotation of the nucleus at this period. The nucleus is prolate (axes a:b:c = 1.9:1:1), a property shared with other nuclei studied using CCD photometry. Novel results include a limit on the bulk density of the nucleus, rho above 300 kg/cu m, and a 20-A-resolution CCD spectrum of the nucleus. Spatially and temporally resolved photometry is used to study the effects of nucleus rotation on the coma. The coma does not share the dramatic photometric variations shown by the nucleus. It possesses a steep surface-brightness distribution, which is attributable to progressive destruction of the coma grains with increasing space exposure.