Relative Intensities of Selected SI II Multiplets in the Spectrum of the Sun and Zeta
Abstract
The relative intensities of five multiplets of Siii are calculated by assuming that the excited levels are populated only by collisional excitation from the ground term; these are compared with the values ob- served in the spectrum of the Sun and ZETA. The observed intensity of the multiplet at 1195 A, relative to that at 1309 A, is an order of magnitude weaker than calculated, while the observed intensity of the multiplet at 1817 A, relative to that at 1309 A, is an order of magnitude stronger than calculated. It is suggested that the great strength of the latter multiplet is due to stepwise excitations via the metastable 3s3p2 4F levels and that the collision strength for the transition 3s3p2 4P312 ,b/2-3s3P2 2D512 is ~1 ~ 10. A complete solution to these problems must await more accurate cross-sections
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 1969
- DOI:
- 10.1086/149946
- Bibcode:
- 1969ApJ...156...49J