Submillimeter Images of a Dusty Kuiper Belt around η Corvi

Abstract

We present submillimeter and mid-IR images of the circumstellar disk around the nearby F2 V star η Corvi. The disk is resolved at 850 μm with a size of ~100 AU. At 450 μm the emission is found to be extended at all position angles, with significant elongation along a position angle of 130deg+/-10deg at the highest resolution (9.3"), this emission is resolved into two peaks that are within the uncertainties offset symmetrically from the star at 100 AU projected separation. Modeling the appearance of emission from a narrow ring in the submillimeter images shows that the observed structure cannot be caused by an edge-on or face-on axisymmetric ring; the observations are consistent with a ring of radius 150+/-20 AU seen at 45deg+/-25deg inclination. More face-on orientations are possible if the dust distribution includes two clumps similar to Vega; we show how such a clumpy structure could arise from the migration over 25 Myr of a Neptune mass planet from 80 to 105 AU. The inner 100 AU of the system appears relatively empty of submillimeter-emitting dust, indicating that this region may have been cleared by the formation of planets, but the disk emission spectrum shows that IRAS detected an additional hot component with a characteristic temperature of 370+/-60 K (implying a distance of 1-2 AU). At 11.9 μm we found the emission to be unresolved, with no background sources that could be contaminating the fluxes measured by IRAS. The age of this star is estimated to be ~1 Gyr. It is very unusual for such an old main-sequence star to exhibit significant mid-IR emission. The proximity of this source makes it a perfect candidate for further study from optical to millimeter wavelengths to determine the distribution of its dust.