The dust properties of a short period comet: comet P/Borrelly

We have calculated the thermal emission spectrum of the dust of comet P/Borrelly (1994l), a short-period comet (Jupiter family), from 3 μm to 14 μm as well as the 10 μm silicate feature in terms of the comet dust model as porous aggregates of interstellar grains. Compared to comet P/Halley dust, the dust grains of P/Borrelly appear to be relatively more processed (more carbonized), less fluffy, and richer in smaller particles. The fluffy aggregate model of silicate core-amorphous carbon mantle grains with a porosity P = 0.85 can match the observational data. To generalize the dust properties of shortperiod comets, systematic observations of the thermal emission spectra and the silicate features for a large set of samples are needed.