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

TL;DR

This study combines sub-millimetre and far-infrared imaging data to analyze the structure and dust properties of the debris disk around HD 76582, revealing a multi-annular architecture and steep particle size distribution.

Contribution

It presents a self-consistent modeling of multi-wavelength data to characterize the complex architecture and dust grain size distribution of the HD 76582 debris disk.

Findings

Extended emission constrains outer disk location.

Steep dust grain size distribution suggests non-steady-state processes.

Disk comprises three distinct annuli with specific radii.

Abstract

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~$\mu$m reveal a steep fall-off that we interpret as a disk dominated by moderately-sized dust grains ($a_{\rm min}~=~36~\mu$m), perhaps indicative of a non-steady-state collisional cascade within the disk. A disk architecture of three distinct annuli, comprising an unresolved component at $\sim$ 20 au and outer components at 80 and 270 au, along with a very steep particle size distribution ($\gamma~=~5$), is proposed to match the observations.