The Structure of NGC 1976 in the Radio Range, v2
  High angular resolution radio continuum images of NGC 1976 (M42, Orion A) at
frequency=330 MHz (wavelength=91 cm), 1.5 GHz (20 cm) and 10.6 GHz (2.8 cm),
have been aligned, placed on a common grid, smoothed to common resolutions of
80" (=0.16 pc at 420 pc) and 90" (=0.18 pc) and compared on a
position-by-position basis. The results are not consistent with a single value
of Te. The best fit to the continuum data is a multi-layer model based on radio
recombination line (RRL) data with a monotonic variation, from Te=8500K in the
higher intensity, more compact region at the rear of NGC 1976 to Te =6000K in
the low intensity, extended region in the foreground. An estimate of
temperature fluctuations toward the peak from this model yields t2=0.003. This
is a factor of 10 lower than fluctuation values from optical collisionally
excited line data.
