Physical Relation of Source I to IRc2 in the Orion KL Region

TL;DR

This study uses mid-infrared imaging and spectroscopy to analyze the structure and heating mechanisms of IRc2 and source I in the Orion KL region, revealing IRc2 is heated by source I rather than being self-luminous.

Contribution

It provides high-resolution mid-infrared observations showing IRc2 is externally heated by source I, and details the temperature distribution and spectral energy characteristics in the Orion KL region.

Findings

IRc2 is not self-luminous but heated by source I

A mid-infrared counterpart to source I was detected

Temperature gradient from IRc2 to source I

Abstract

We present mid-infrared narrow-band images of the Orion BN/KL region, and N-band low-resolution spectra of IRc2 and the nearby radio source "I." The distributions of the silicate absorption strength and the color temperature have been revealed with a sub-arcsecond resolution. The detailed structure of the 7.8 micron/12.4 micron color temperature distribution was resolved in the vicinity of IRc2. A mid-infrared counterpart to source I has been detected as a large color temperature peak. The color temperature distribution shows an increasing gradient from IRc2 toward source I, and no dominant temperature peak is seen at IRc2. The spectral energy distribution of IRc2 could be fitted by a two-temperature component model, and the "warmer component" of the infrared emission from IRc2 could be reproduced by scattering of radiation from source I. IRc2 itself is not self-luminous, but is illuminated and heated by an embedded luminous young stellar object located at source I.