ISSN:
1572-9672
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract Observations of the solar spectrum have been made between 1200–2200 Å with high spectral resolution. The results were obtained with an all-reflecting echelle spectrograph carried by a stabilized Skylark rocket launched in April 1970. Measurements of the profiles of a number of emission lines due to Siii, Cii, Siiii and Civ formed in the temperature range 104-105 K, indicate ion energies which are considerably in excess of the electron temperatures derived from the ionization balance. Since the ion/electron relaxation time is very short the observed ion energies cannot correspond to an ion temperature and hence a non-thermal mechanical energy component exists in the transition zone. It is postulated that the non-thermal energy component represents the actual mechanical energy responsible for the heating of the corona, and, that, it is propagated as an acoustic wave. On this basis and with a preliminary estimate of the reflection from the transition zone, a flux of 3 × 105 erg cm -2 s -1 is established as entering the corona. This value is in agreement with estimates of the total energy loss from the corona due to conduction, radiation and the solar wind, thus establishing a gross energy balance. Theoretical calculations are currently underway to establish the physical nature of the atmosphere which would result from such a propagating flux. At the present time this has been carried out for an atmosphere in hydrostatic equilibrium and the energy balance equation solved. A preliminary temperature structure which results is shown in Figure 1, together with the derived distribution in electron density. This gives a corona of the right temperature and density but the observed structure deviates in detail from those derived from an analysis of the solar XUV spectrum.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00213496
Permalink
