Journal
ASTRONOMY & ASTROPHYSICS
Volume 422, Issue 1, Pages 331-336Publisher
EDP SCIENCES S A
DOI: 10.1051/0004-6361:20035787
Keywords
radiation mechanisms : non-thermal; Sun : transition region; Sun : corona; Sun : radio radiation
Categories
Ask authors/readers for more resources
The bremsstrahlung emissivity and absorption coefficient in the radiofrequency range are derived under the assumption that the electron population is not purely thermal, but presents a tail of high energy particles. This population is approximated by a two-component Maxwellian distribution and by the kappa-functions of different (integer) index. It is shown that, if the temperature ratio of the two Maxwellians is larger than 10, the absorption coefficient and the effective temperature (the quantities entering the radio transfer equation) depend only on the fraction R of particles in the highest temperature Maxwellian. In the case of kappa-functions the above quantities depend on the index n of the functions. The microwave radio spectrum is computed for different values of R and for 3 less than or equal to n less than or equal to 6, finding, in all cases, brightness temperatures lower than those computed with a pure thermal distribution. This could explain some inconsistencies found between radio and EUV observations.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available