SCUBA imaging of the NGC 7331 dust ring

We present observations of the spiral galaxy NGC 7331 using the Submillimetre Common User Bolometer Array (SCUBA) on the James Clark Maxwell Telescope. We have detected a dust ring of 45 arcsec radius (3.3 kpc) at wavelengths of 450 and 850 mu m. The dust ring is in good correspondence with other observations of the ring in the mid-infrared (MTR), CO and radio continuum, suggesting that the observed dust is associated with molecular gas and star formation. A B - K colour map shows an analogous ring structure with an asymmetry about the major axis, consistent with the extinction being produced by a dust ring. The derived temperature of the dust lies between 16 and 31 K and the gas-to-dust ratio lies between 150 and 570, depending on the assumed dust emission efficiency index (beta = 1.5 or 2).