An 850 μm Survey for Dust around Solar‐Mass Stars

We present the results of an 850 micron JCMT/SCUBA survey for dust around 13nearby solar mass stars. The dust mass sensitivity ranged from 0.005 to 0.16Earth masses. Three sources were detected in the survey, one of which (HD107146) has been previously reported. One of the other two submillimetersources, HD 104860, was not detected by IRAS and is surrounded by a cold,massive dust disk with a dust temperature and mass of Tdust = 33 K and Mdust =0.16 Mearth. The third source, HD 8907, was detected by IRAS and ISO at 60-87microns, and has a dust temperature and mass Tdust = 48 K and Mdust = 0.036Mearth. We find that the deduced masses and radii of the dust disks in oursample are roughly consistent with models for the collisional evolution ofplanetesimal disks with embedded planets. We also searched for residual gas intwo of the three systems with detected submillimeter excesses and place limitson the mass of gas residing in these systems. When the properties measured for the detected excess sources are combinedwith the larger population of submillimeter excess sources from the literature,we find strong evidence that the mass in small grains declines significantly ona ~200 Myr timescale, approximately inversely with age. However, we also findthat the characteristic dust radii of the population, obtained from the dusttemperature of the excess and assuming blackbody grains, is uncorrelated withage. This is in contrast to self-stirred collisional models for debris diskevolution which predict a trend of radius increasing with age, t ~ R^3. Thelack of agreement suggests that processes beyond self-stirring, such as giantplanet formation, play a role in the evolutionary histories of planetesimaldisks.Comment: 31 pages, 5 figures. Accepted for publication in the Ap