2011/11/30 by T. L. Wilson, Simón Casassus, Wilson, T. L. +4
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Gamma-ray bursts and supernovae #Stellar, planetary, and galactic studies #astro-ph.GA
paper · pdf · doi:10.48550/arxiv.1112.0047
22 pages, 4 figures, 1 table; revised acknowledgements and last author's name changed
arxiv created 2011/11/30 · openalex publication_date 2011/11/30 · arxiv updated 2011/12/02 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
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.