The Dust Properties of Eight Debris Disk Candidates as Determined by Submillimeter Photometry

The nature of far-infrared dust emission toward main sequence stars, whetherinterstellar or circumstellar, can be deduced from submillimeter photometry. Wepresent JCMT/SCUBA flux measurements at 850 microns toward 8 stars with largephotospheric excesses at 60-100 microns. 5 sources were detected at 3-sigma orgreater significance and one was marginally detected at 2.5-sigma. The inferreddust masses and temperatures range from 0.033 to 0.24 Earth masses and 43-65 Krespectively. The frequency behavior of the opacity, tau_nu ~ nu^beta, isrelatively shallow, beta < 1. These dust properties are characteristic ofcircumstellar material, most likely the debris from planetesimal collisions.The 2 non-detections have lower temperatures, 35-38 K and steeper opacityindices, beta > 1.5, that are more typical of interstellar cirrus. Theconfirmed disks all have inferred diameters > 2'', most lie near the upperenvelope of the debris disk mass distribution, and 4 are bright enough to befeasible for high resolution imaging.Comment: accepted by Ap