Earth, Moon, and Planets

, Volume 89, Issue 1, pp 3-25

First online:

The Nucleus of Comet Hale-Bopp (C/1995 O1): Size and Activity

  • Yanga R. FernándezAffiliated withInstitute for Astronomy, University of Hawaii

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A review of our current understanding of Comet Hale-Bopp’s nuclear size is presented. Currently the best constraints on the effective radiusare derived from late-1996 mid-IR data and near-perihelion radio data.Unfortunately the two regimes give differing answers for the radius. A possible reconciliation of the two datasets is presented that would place the radius at around 30 km. This is a large cometary radius compared to the others that are known, and this motivates a discussion of what makes a large comet different. From several possible large-comet properties, Hale-Bopp’s activity is analyzed, focusing on the production rates, coma jet features, dust optical depth, and relationship with the interplanetary dust environment. The optical depth is particularly important since an optically-thick inner coma could complicate attempted measurements of the “nucleus”.

Comets Hale-Bopp