SOFIA/FORCAST Observations of Warm Dust in S106: A Fragmented Environment

TL;DR

This study uses multi-wavelength infrared observations and modeling to analyze the heating, composition, and fragmented dust environment in S106, revealing temperature gradients and dust properties around the source S106 IR.

Contribution

It provides detailed dust composition and temperature distribution analysis in S106 using new SOFIA/FORCAST data combined with other IR observations.

Findings

Dust heated mainly by S106 IR with minimal other contributions.

Temperature gradient observed from 75 to 107 K in the lobes.

Environment is fragmented with cool lanes and pockets of warmer dust.

Abstract

We present mid-IR (19 - 37 microns) imaging observations of S106 from SOFIA/FORCAST, complemented with IR observations from Spitzer/IRAC (3.6 - 8.0 microns), IRTF/MIRLIN (11.3 and 12.5 microns), and Herschel/PACS (70 and 160 microns). We use these observations, observations in the literature, and radiation transfer modeling to study the heating and composition of the warm (~ 100 K) dust in the region. The dust is heated radiatively by the source S106 IR, with little contributions from grain-electron collisions and Ly-alpha radiation. The dust luminosity is >~ (9.02 +/- 1.01) x 10^4 L_sun, consistent with heating by a mid- to late-type O star. We find a temperature gradient (~ 75 - 107 K) in the lobes, which is consistent with a dusty equatorial geometry around S106 IR. Furthermore, the SOFIA observations resolve several cool (~ 65 - 70 K) lanes and pockets of warmer (~ 75 - 90 K) dust in the ionization shadow, indicating that the environment is fragmented. We model the dust mass as a composition of amorphous silicates, amorphous carbon, big grains, very small grains, and PAHs. We present the relative abundances of each grain component for several locations in S106.