Imaging of Debris Disks

Imaging of debris disks is of crucial importance. This not just confirms the disk interpretation of the infrared excess, but also directly shows the radial location of the dust (and so the location of the Asteroid and Kuiper Belts in these systems). Imaging has also been used to identify asymmetries in the disk structures which have revolutionised our understanding of the outcome of planet formation in these systems, since they have been shown to be evidence for planets orbiting several 10s of AU from the star.

Because the dust emission of the majority of the disks we know about is cold (<100 K), the sub-millimetre has been the most productive wavelength range for imaging studies. Until 1998, only the disk of β Pictoris had been imaged. Then three further disk images were obtained using the sub-millimetre instrument SCUBA, which was built here at the Royal Observatory Edinburgh. These images, made at a wavelength of 850 µm, confirmed the dust is located 40-140 AU from these stars and also showed these dust rings to be significantly clumpy (Holland et al. 1998; Greaves et al. 1998):

More recently much higher resolution images of these disks have been obtained using the 450 µm imaging capability of SCUBA. The results for Fomalhaut were published in Holland et al. (2003) and show a bend in the emission between the lobes of this edge-on dust ring.

An imaging programme using SCUBA to survey nearby stars for extended emission has also recently been completed, and has resulted in resolved images of a further four disks (Wyatt et al., in prep.; Greaves et al., in prep.).

The Royal Observatory Edinburgh comprises the UK Astronomy Technology Centre of the Science and Technology Facilities Council, the Institute for Astronomy of the University of Edinburgh and the ROE Visitor Centre.