A two-zone steady state crystallization model for comets

Dina Prialnik*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

An analytic two-zone model for the advance of a crystallization front through a porous amorphous ice medium is proposed. Such a model is justified by the extremely low thermal conductivity of cold amorphous ice on the one hand, and by the very high thermal conductivity of vapor-filled porous crystalline ice on the other hand. Steady state solutions are sought, where the only energy source is the heat released upon crystallization. Part of this energy is used in sublimation of the ice at the free boundary of the crystalline layer, and part is used in heating of the amorphous ice that sustains the crystallization process. It is shown that this process is capable of maintaining quite high temperatures throughout the crystalline layer behind the phase-transition front. These result in high rates of sublimation. The implication for comet nuclei is that high levels of activity may be encountered in comets at heliocentric distances where insolation is negligible. The merit of such a model is that it leads to general conclusions, regardless of the orbits of individual comets.

Original languageEnglish
Pages (from-to)L49-L52
JournalAstrophysical Journal
Volume418
Issue number1 PART 2
DOIs
StatePublished - 20 Nov 1993

Keywords

  • Comets: general

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