Mid-infrared spectroscopy of Beta Pictoris: constraints on the dust grain size

Abstract

We present 8–13 μm spectroscopy of Beta Pictoris which confirms the presence of silicate emission in its infrared excess, as earlier reported on the basis of narrow-band photometry, and indicates a similarity with cometary dust. The spectral form of the infrared excess allows us to place an upper limit of 2–3 μm on the size of the emitting grains in the circumstellar disc.