engleski

Identification of features in solar ALMA images and comparison with solar atmospheric models

Various solar features were identified in the full-disc single-dish ALMA images taken at wavelength of 1.2 and 2.8 mm and compared with Hα, Ca II K and EUV images and magnetograms. Assuming thermal bremsstrahlung as the dominant radiation mechanism, several models were constructed to calculate the brightness temperature of various solar features (quiet and active solar regions, filaments and coronal holes) in a wavelength range from 0.3 to 10 mm. It is found that model predictions are in a qualitative agreement with ALMA images where active regions appear brighter, while filaments and coronal holes are not discernible from the quiet Sun level. It is also found that in ALMA images regions around magnetic neutral lines appear darker than the quiet Sun. Models predict a critical frequency below which filaments should appear in absorption and above it in emission.

ALMA ; Sun

nije evidentirano