Friday, October 21, 2011

1110.4521 (T. L. Wilson et al.)

The Structure of NGC 1976 in the Radio Range    [PDF]

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

No comments:

Post a Comment