EUV analysis of an active region |
| |
Authors: | Nirupama Raghavan George L. Withbroe |
| |
Affiliation: | 1. Center for Astrophysics, Harvard College Observatory and Smithsonian Astrophysical Observatory, 02138, Cambridge, Mass., U.S.A.
|
| |
Abstract: | A sequence of extreme ultraviolet (EUV) spectroheliograms of McMath region No. 10283 were obtained by the Harvard College Observatory experiment on OSO-6. The lines Ovi λ1032 Mg × λ625, Si xii λ499 and Fe xvi λ 335 were used to determine coronal temperatures and densities above the active region. A comparison of theoretical and observed line ratios yielded coronal temperatures of 2.2 to 2.3 × 106K above the active region and 2.0 to 2.1 × 106K in the surrounding area. The temperatures derived from ratios involving the O vi intensities are systematically higher than the others. This is attributed to an error in the theoretical O vi intensities. The intensities observed above the limb are compared with intensities predicted with a simple model based on cylindrical geometry. The overall agreement shows that the assumption of an iso-thermal corona in hydrostatic equilibrium above the active region is a reasonable working hypothesis and that the adopted geometrical model for the electron density distribution is adequate. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|