Gas and Dust Absorption in the DoAr 24E System

TL;DR

This study investigates the disk structure and extinction sources in the binary system DoAr 24E, using infrared spectroscopy, imaging, and modeling to understand the origin of high extinction toward its infrared companion.

Contribution

It provides new insights into the disk and extinction characteristics of DoAr 24E, highlighting the role of a disk or disk wind in causing high extinction.

Findings

Mid-infrared continuum less extinguished than near-infrared

Lack of silicate absorption indicates extended emission region

CO absorption velocity profile suggests disk or disk wind as extinction source

Abstract

We present findings for DoAr 24E, a binary system that includes a classical infrared companion. We observed the DoAr 24E system with the Spitzer Infrared Spectrograph (IRS), with high-resolution, near-infrared spectroscopy of CO vibrational transitions, and with mid-infrared imaging. The source of high extinction toward infrared companions has been an item of continuing interest. Here we investigate the disk structure of DoAr 24E using the column densities, temperature, and velocity profiles of two CO absorption features seen toward DoAr 24Eb. We model the SEDs found using T-ReCS imaging, and investigate the likely sources of extinction toward DoAr 24Eb. We find the lack of silicate absorption and small CO column density toward DoAr 24Eb suggest the mid-infrared continuum is not as extinguished as the near-infrared, possibly due to the mid-infrared originating from an extended region. This, along with the velocity profile of the CO absorption, suggests the source of high extinction is likely due to a disk or disk wind associated with DoAr 24Eb.