Open AccessA mechanism for short‐lived cometary outbursts at sunrise as observed by Deep Impact on 9P/Tempel 1
Author(s) -
Prialnik D.,
A'Hearn M. F.,
Meech K. J.
Publication year - 2008
Publication title -
monthly notices of the royal astronomical society: letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.067
H-Index - 122
eISSN - 1745-3933
pISSN - 1745-3925
DOI - 10.1111/j.1745-3933.2008.00491.x
Subject(s) - sunrise , noon , atmospheric sciences , comet , geology , surface layer , physics , meteorology , astrophysics , layer (electronics) , materials science , composite material
We explore a possible mechanism that may explain the outbursts observed by the Deep Impact mission on comet 9P/Tempel 1 that appear to occur near sunrise on a particular area. Assuming that the area is covered by a porous, poorly conducting dust layer, the heat wave generated by solar radiation at local noon propagates through the dust layer towards the ice‐rich layer underneath it. The heated ice sublimates and the vapour flows towards the surface. However, by the time the heat wave reaches the ice, the spot has moved out of sunlight and its temperature has started dropping. As the vapour flows outwards, the surface has become so cold that it refreezes. Thus, at night some ice accumulates in the dust layer, very close to the surface. At sunrise, it immediately evaporates, producing a short‐lived surge of activity. Numerical simulations of this mechanism provide the duration and water production of such outbursts, which are compatible with the 9P/Tempel 1 observations of small outbursts.