Solar System Analogs Around IRAS-Discovered Debris Disks

TL;DR

This study reanalyzed Spitzer IRS spectra and SEDs of three nearby debris disks, revealing their thermal emission is well modeled with two black body components and providing insights into their structure and composition.

Contribution

The paper presents a detailed reanalysis of debris disks around lambda Boo, HD 139664, and HR 8799, offering new interpretations of their dust distributions and grain properties.

Findings

HR 8799 has an asteroid belt and Kuiper Belt with no silicate features.

HD 139664's outer disk contains porous, forward-scattering grains.

lambda Boo system shows a central clearing, indicating no dust accretion onto the star.

Abstract

We have rereduced Spitzer IRS spectra and reanalyzed the SED's of three nearby debris disks: lambda Boo, HD 139664, and HR 8799. We find that that the thermal emission from these objects is well modeled using two single temperature black body components. For HR 8799 -- with no silicate emission features despite a relatively hot inner dust component (Tgr = 150 K) -- we infer the presence of an asteroid belt interior to and a Kuiper Belt exterior to the recently discovered orbiting planets. For HD 139664, which has been imaged in scattered light, we infer the presence of strongly forward scattering grains, consistent with porous grains, if the cold, outer disk component generates both the observed scattered light and thermal emission. Finally, careful analysis of the lambda Boo SED suggests that this system possesses a central clearing, indicating that selective accretion of solids onto the central star does not occur from a dusty disk.