Dusty Cradles in a Turbulent Nursery: The Sgr A East HII Region Complex at the Galactic Center

We present high spatial resolution (FWHM ~ 3.2’’ - 3.8’’) imaging performed by the FORCAST instrument on SOFIA at 19, 25, 31, and 37 μm of the compact HII region complex G-0.02-0.07, the site of the most recent confirmed star formation within ~10 pc of the Galactic center. G-0.02-0.07 contains three compact HII regions (A, B, and C) and one ultra-compact HII region (D). Using this multiband imaging along with DustEM, we constrain the gas-to-dust mass ratios (~45 - 65) and the relative mass abundances of large grains, very small grains, and PAHs in the emitting dust from each region. Combining the inferred stellar luminosities, the expected and observed 1.90 μm fluxes and the observed dust thermal structure, the previously suggested heating sources for regions A, B, and C are confirmed. However, for region D, the observed fluxes at 1.87 and 1.90 μm of the previously proposed ionizing star are a factor of ~40 times too bright to be the heating source. We find that the location of the Region A heating source and the morphology of surrounding dust emission is consistent with that of a bow-shock, which suggests the heating source may have been ejected from its initial birth site rather than forming in-situ. In the ejection scenario for the Region A heating source, we estimate a lower limit on its age of ~10⁴ yrs based on the size of the bow-shock.