On the dust environment of Main-Belt Comet 313P/Gibbs

Abstract

We present observations carried out using the 10.4 m Gran Telescopio Canarias and an interpretative model of the dust environment of activated asteroid 313P/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 with an isotropic emission of particles which started on August 1st. The size of grains were in the range of $0.1-2000$ $\mu$m, with velocities for 100 $\mu$m 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' brightness and morphology are best interpreted in terms of a model of sustained and low dust emission driven by water-ice sublimation, spanning since 2014 August 1st, and triggered by a short impulsive event. This event produced an emission of small particles of about 0.1 $\mu$m with velocities of $\sim$4 m$~$s$^{-1}$. From our model we deduce that the activity of this Main-Belt Comet continued for, at least, four months, since activation.