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Intermittent dust mass loss from activated asteroid P/2013 P5 (PANSTARRS)

We present observations and models of the dust environment of activated asteroid P/2013 P5 (PANSTARRS). The object displayed a complex morphology during the observations, with the presence of multiple tails. We combined our own observations, all made with instrumentation attached to the 10.4m Gran Telescopio Canarias (GTC) on La Palma, with previously published Hubble Space Telescope (HST) images to build a model aimed at fitting all the observations. Altogether, the data cover a full 3-month period of observations which can be explained by an intermittent dust loss. The most plausible scenario is that of an asteroid rotating with the spinning axis oriented perpendicular to the orbit plane and loosing mass from the equatorial region, consistent with a rotational break-up. Assuming that the ejection velocity of the particles (v$\sim$0.02-0.05 m s$^{-1}$) corresponds to the escape velocity, the object diameter is constrained to $\sim$30-130 m for bulk densities 3000 to 1000 kg m$^{-3}$.