Impulsive Activity

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Science  14 Dec 2012:
Vol. 338, Issue 6113, pp. 1397
DOI: 10.1126/science.338.6113.1397-d

Comets and asteroids are normally distinguished on the basis of their composition, appearance, and orbits. Since 2006, however, nine bodies orbiting within the main asteroid belt have been found with physical characteristics similar to those of comets; i.e., comae and narrow dust tails. They have been named main-belt comets and are still enigmatic because they are difficult to find and characterize. Moreno et al. used the Gran Telescopio Canarias, a 10.4-m telescope located in the Canary Islands in Spain, to observe the main-belt comet P/2012 F5 (Gibbs), which was discovered in March 2012—the ninth main-belt comet found. The optical data, obtained on 18 May and 8 June 2012, together with a model to characterize the dust environment around the comet, imply that an impulsive event lasting less than a day, possibly less than a few hours, occurred on 1 July 2011, with an uncertainty of ±10 days, producing the narrow dust trails observed in this comet. It is not possible to say what caused this event, but an outburst, a collision with another body, or a rotational disruption are some of the likely causes. Activity related to ice sublimation, which has been suggested for other main-belt comets, is unlikely, based on the properties of the dust.

Astrophys. J. 761, L12 (2012).

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