The temperature of prominences in active solar regions.
Abstract
Kinetic temperatures of solar prominences may be computed by analyzing the profiles of emission lines from atoms of two different atomic weights. Such temperatures have been computed from the emission lines of hydrogen and helium of prominences appearing on Climax coronal spectrograms. The temperatures found are in the range I0,000O~20,000O for many active prominences, in agreement with the computations of many observers. Certain very active region prominences, however, show temperatures equal to and greater than 100,0000. The mechanism by which hydrogen radiates in Ha at temperatures in excess of 100,0000 is then discussed. By considering the various radiative and collisional processes occurring in an active, hot prominence we determine the equations of statistical equilibrium for the first five hydrogen levels. Solution of these for the occupation numbers of the levels shows that at a density of i0~~ atoms per cm' or greater, a prominence thread 5000 km thick will produce the observed Ha intensity, even though its kinetic temperature is greater than 100,0000. This work was supported in part by the Office of Naval Research through a contract with the University of Colorado and in part by the Air Force Cambridge Research Center, Geophysics Research Directorate through a contract with Harvard University. High Altitude Observatory, Boulder Cob., and Harvard College Observatory, Cambridge, Mass.
- Publication:
-
The Astronomical Journal
- Pub Date:
- 1955
- DOI:
- 10.1086/107128
- Bibcode:
- 1955AJ.....60Q.155B