T. L. Wilson, S. Casassus, Katie M. Chynoweth
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. Rather, there is a significant variation, from Te =6000K in the low
intensity, extended region to Te=8500K in the higher intensity, more compact
region. The best fit to the data is a multi-layer model obtained from radio
recombination line (RRL) data. An estimate of temperature fluctuations from the
model yields t2=0.003. This is a factor of 10 lower than fluctuation values
from optical O++ line data.
View original:
http://arxiv.org/abs/1110.4521
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