Modeling the HD32297 Debris Disk with Far-IR Herschel Data

TL;DR

This study models the dust composition and structure of the HD32297 debris disk using far-infrared Herschel data, revealing a two-component disk with comet-like grains and circumstellar gas detection.

Contribution

First detailed SED modeling of HD32297 debris disk combining far-IR data with resolved imaging to determine dust composition and disk structure.

Findings

Disk has two components: an outer ring at 110 AU and an inner disk near habitable zone.

Outer disk grains are > 2μm, composed of silicates, carbon, and water ice with specific ratios.

Detected [C II] emission indicating the presence of circumstellar gas.

Abstract

HD32297 is a young A-star (~30 Myr) 112 pc away with a bright edge-on debris disk that has been resolved in scattered light. We observed the HD32297 debris disk in the far-infrared and sub-millimeter with the Herschel Space Observatory PACS and SPIRE instruments, populating the spectral energy distribution (SED) from 63 to 500{\mu}m. We aimed to determine the composition of dust grains in the HD32297 disk through SED modeling, using geometrical constraints from the resolved imaging to break degeneracies inherent in SED modeling. We found the best fitting SED model has 2 components: an outer ring centered around 110 AU, seen in the scattered light images, and an inner disk near the habitable zone of the star. The outer disk appears to be composed of grains > 2{\mu}m consisting of silicates, carbonaceous material, and water ice with an abundance ratio of 1:2:3 respectively and 90% porosity. These grains appear consistent with cometary grains, implying the underlying planetesimal population is dominated by comet-like bodies. We also discuss the 3.7{\sigma} detection of [C II] emission at 158{\mu}m with the Herschel PACS Spectrometer, making HD32297 one of only a handful of debris disks with circumstellar gas detected.