2003ApJ...584L..33W

Long-slit spectra probe the southwest side of the disk in the 8-13 µm region. Dust within 0".8 of the star shows silicate emission features, including amorphous and crystalline species. Farther out, the disk spectra are featureless and are entirely dominated by dust thermal continuum emission. Mid-infrared imaging of β Pictoris reveals spatial asymmetries in its dusty circumstellar disk at a spatial resolution of 0".5. Visible for the first time is an inner (r<20 AU) warp in the disk that is aligned differently from a larger scale warp observed in scattered light by the Hubble Space Telescope. At 12 µm, as has been observed before, the southwest extension of the disk is brighter than the northeast side. This asymmetry appears to be not as significant at 18 µm. The spatially resolved spectra show that this asymmetry cannot be accounted for by small dust grains that have a spectral feature.