Herschel PACS Observations and Modeling of Debris Disks in the Tucana-Horologium Association

TL;DR

This study uses Herschel PACS observations to identify and model debris disks around young stars in the Tucana-Horologium Association, revealing new disks and characterizing their dust properties and geometries.

Contribution

It provides the first detailed modeling of debris disks in this association, including a newly discovered disk around HD30051, and advances understanding of dust characteristics in young stellar systems.

Findings

Six stars have significant infrared excesses indicating debris disks.

The disks' dust temperatures and masses were estimated through modeling.

A new debris disk was discovered around HD30051.

Abstract

We present Herschel PACS photometry of seventeen B- to M-type stars in the 30 Myr-old Tucana-Horologium Association. This work is part of the Herschel Open Time Key Programme "Gas in Protoplanetary Systems" (GASPS). Six of the seventeen targets were found to have infrared excesses significantly greater than the expected stellar IR fluxes, including a previously unknown disk around HD30051. These six debris disks were fitted with single-temperature blackbody models to estimate the temperatures and abundances of the dust in the systems. For the five stars that show excess emission in the Herschel PACS photometry and also have Spitzer IRS spectra, we fit the data with models of optically thin debris disks with realistic grain properties in order to better estimate the disk parameters. The model is determined by a set of six parameters: surface density index, grain size distribution index, minimum and maximum grain sizes, and the inner and outer radii of the disk. The best fitting parameters give us constraints on the geometry of the dust in these systems, as well as lower limits to the total dust masses. The HD105 disk was further constrained by fitting marginally resolved PACS 70 micron imaging.