Sunday, May 8, 2016

Far-infrared and sub-millimetre imaging of HD 76582's circumstellar disk

Far-infrared and sub-millimetre imaging of HD~76582's circumstellar disk

Marshall et al


Debris disks, the tenuous rocky and icy remnants of planet formation, are believed to be evidence for planetary systems around other stars. The JCMT/SCUBA-2 debris disk legacy survey 'SCUBA-2 Observations of Nearby Stars' (SONS) observed 100 nearby stars, amongst them HD~76582, for evidence of such material. Here we present imaging observations by JCMT/SCUBA-2 and \textit{Herschel}/PACS at sub-millimetre and far-infrared wavelengths, respectively. We simultaneously model the ensemble of photometric and imaging data, spanning optical to sub-millimetre wavelengths, in a self-consistent manner. At far-infrared wavelengths, we find extended emission from the circumstellar disk providing a strong constraint on the dust spatial location in the outer system, although the angular resolution is too poor to constrain the interior of the system. In the sub-millimetre, photometry at 450 and 850~μm reveal a steep fall-off that we interpret as a disk dominated by moderately-sized dust grains (amin = 36 μm), perhaps indicative of a non-steady-state collisional cascade within the disk. A disk architecture of three distinct annuli, comprising an unresolved component at ∼ 20 au and outer components at 80 and 270 au, along with a very steep particle size distribution (γ = 5), is proposed to match the observations.

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