We present a model of the dust environment of Main-Belt Comet P/2010 R2
(La Sagra) from images acquired during the period 2010 October-2011
January. The tails are best simulated by anisotropic ejection models,
with emission concentrated near the nucleus south pole, the spin axis
having an obliquity near 90°, indicative of a possible seasonally
driven behavior. The dust mass loss rate increases rapidly shortly
before perihelion, reaching a maximum value of ~4 kg s-1, and
maintaining a sustained, cometary-like, activity of about 3-4 kg
s-1 up to at least 200 days after perihelion, the date of the
latest observation. The size distribution function is characterized by
particles in the 5 × 10-4 cm to 1 cm radius range,
assuming a time-constant power-law distribution with an index of -3.5.
The ejection velocities are compatible with water-ice sublimation
activity at the heliocentric distance of 2.7 AU, with values of 10-20 cm
s-1 for particle radius of 1 cm, and inverse square root
dependence on particle size, typical of hydrodynamical gas drag.