First Science Observations with SOFIA/FORCAST: 6 to 37 micron Imaging of the Central Orion Nebula

TL;DR

This paper presents high-resolution mid-infrared images of the Orion Nebula using SOFIA/FORCAST, revealing detailed structures, embedded objects, and the nebula's morphology at wavelengths from 6 to 37 microns.

Contribution

First high-resolution 6-37 micron imaging of the Orion Nebula with SOFIA/FORCAST, including detailed morphology and embedded object analysis.

Findings

Ney-Allen Nebula morphology consistent with stellar wind interaction

Detection of two proplyds and several embedded YSOs

Spectral energy distribution modeling constrains YSO properties

Abstract

We present new mid-infrared images of the central region of the Orion Nebula using the newly commissioned SOFIA airborne telescope and its 5 -- 40 micron camera FORCAST. The 37.1 micron images represent the highest resolution observations (<4") ever obtained of this region at these wavelengths. After BN/KL (which is described in a separate letter in this issue), the dominant source at all wavelengths except 37.1 micron is the Ney-Allen Nebula, a crescent-shaped extended source associated with theta 1D. The morphology of the Ney-Allen nebula in our images is consistent with the interpretation that it is ambient dust swept up by the stellar wind from theta 1D, as suggested by Smith et al. (2005). Our observations also reveal emission from two "proplyds" (proto-planetary disks), and a few embedded young stellar objects (YSOs; IRc9, and OMC1S IRS1, 2, and 10). The spectral energy distribution for IRc9 is presented and fitted with standard YSO models from Robitaille et al. (2007) to constrain the total luminosity, disk size, and envelope size. The diffuse, nebular emission we observe at all FORCAST wavelengths is most likely from the background photodissociation region (PDR) and shows structure that coincides roughly with H_alpha and [N II] emission. We conclude that the spatial variations in the diffuse emission are likely due to undulations in the surface of the background PDR.