A Possible Icy Kuiper Belt around HD 181327

TL;DR

This study presents the first resolved thermal-emission image of HD 181327's disk, suggesting the presence of icy debris possibly replenished by collisions among Kuiper belt-like objects in a young planetary system.

Contribution

It provides the first resolved thermal-emission image of the disk around HD 181327 and proposes the detection of icy debris replenished by collisions.

Findings

Northern arm of the disk is 1.4 times brighter than the southern arm.

Detected a broad peak at 60-75 microns indicating crystalline water ice.

Icy debris may be replenished by collisions among Kuiper belt-like objects.

Abstract

We have obtained a Gemini South T-ReCS Qa-band (18.3 micron) image and a Spitzer MIPS SED-mode observation of HD181327, an F5/F6V member of the ~12 Myr old beta Pictoris moving group. We resolve the disk in thermal-emission for the first time and find that the northern arm of the disk is 1.4x brighter than the southern arm. In addition, we detect a broad peak in the combined Spitzer IRS and MIPS spectra at 60 - 75 micron that may be produced by emission from crystalline water ice. We model the IRS and MIPS data using a size distribution of amorphous olivine and water ice grains (dn/da proportional to a^{-2.25} with a_{min} consistent with the minimum blow out size and a_{max} = 20 micron) located at a distance of 86.3 AU from the central star, as observed in previously published scattered-light images. Since the photo-desorption lifetime for the icy particles is ~1400 yr, significantly less than the estimated ~12 Myr age of the system, we hypothesize that we have detected debris that may be steadily replenished by collisions among icy Kuiper belt object-like parent bodies in a newly forming planetary system.