skip to main content

Title: Dusty cradles in a turbulent nursery: the SGR A east H II region complex at the galactic center

We present imaging at 19, 25, 31, and 37 μm of the compact H II region complex G-0.02-0.07 located 6 pc in projection from the center of the Galaxy obtained with SOFIA using FORCAST. G-0.02-0.07 contains three compact H II regions (A, B, and C) and one ultra-compact H II region (D). Our observations reveal the presence of two faint, infrared sources located 23'' and 35'' to the east of region C (FIRS 1 and 2) and detect dust emission in two of the three 'ridges' of ionized gas west of region A. The 19/37 color temperature and 37 μm optical depth maps of regions A-C are used to characterize the dust energetics and morphology. Regions A and B exhibit average 19/37 color temperatures of ∼105 K, and regions C and D exhibit color temperatures of ∼115 K and ∼130 K, respectively. Using the DustEM code, we model the SEDs of regions A-D and FIRS 1, all of which require populations of very small, transiently heated grains and large, equilibrium-heated grains. We also require the presence of polycyclic aromatic hydrocarbons in regions A-C in order to fit the 3.6, 4.5, 5.8, and 8.0 μm fluxes observed by Spitzer/IRAC. The locationmore » of the heating source for region A is determined by triangulation from distances and temperatures derived from DustEM models fit to SEDs of three different points around the region, and it is found to be displaced to the northeast of the center of curvature near the color temperature peak. Based on total luminosity, expected 1.90 μm fluxes, and proximity to the mid-IR color temperature peaks, we identify heating source candidates for regions A, B, and C. 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 and hence is likely just a star lying along the line of sight toward region D.« less
Authors:
; ;  [1] ;  [2]
  1. Astronomy Department, Cornell University, 202 Space Sciences Building, Ithaca, NY 14853-6801 (United States)
  2. Department of Physics and Astronomy, University of California, Los Angeles, 430 Portola Plaza, Los Angeles, CA 90095-1547 (United States)
Publication Date:
OSTI Identifier:
22370428
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 794; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COLOR; DUSTS; EMISSION; EQUILIBRIUM; GALAXIES; HEATING; LUMINOSITY; MAPS; POLYCYCLIC AROMATIC HYDROCARBONS; STARS; TRANSIENTS