ON the DUST ENVIRONMENT of MAIN-BELT COMET 313 P/Gibbs

We present observations carried out using the 10.4 m Gran Telescopio Canarias and an interpretative model of the dust environment of activated asteroid 313 P/Gibbs. We discuss three different models relating to different values of the dust parameters, i.e., dust loss rate, maximum and minimum sizes of particles, power index of the size distribution, and emission pattern. The best model corresponds to an isotropic emission of particles which started on August 1. The sizes of grains were in the range of 0.1-2000 μm, with velocities for 100 μm particles between 0.4-1.9 m s-1, with a dust production rate in the range of 0.2-0.8 kg s-1. The dust tails' brightnesses and morphologies are best interpreted in terms of a model of sustained and low dust emission driven by water-ice sublimation, spanning since 2014 August 1, and triggered by a short impulsive event. This event produced an emission of small particles of about 0.1 μm with velocities of ∼4 m s-1. From our model we deduce that the activity of this main-belt comet continued for at least four months since activation. © 2015. The American Astronomical Society. All rights reserved.