Measurements of the Iron-Group Abundance in Energetic Solar Particles
Abstract
The abundance of iron-group nuclei in the energetic solar particles was measured twice in the 1971 January 24 event and once in the 1971 September 2 event. Including earlier results from the 1966 September 2 event, the experimental series being discussed in this article has found the iron- group abundance to be in the range from 3-6 percent of the oxygen nuclei in the energy interval from 21 to 50 MeV per nucleon, in those events where the iron-group abundance could be measured. Iron-nuclei have a different charge-to-mass ratio from that of the C, N, 0 nuclei, so small variations in the Fe abundance in solar particles are not unexpected due to rigidity-dependent propagation effects and possibly rigidity-dependent acceleration. In the three exposures where the statistics were adequate to construct an energy spectrum, the iron-group nuclei were seen to have an energy per nucleon spectrum similar to that of the C, N, 0 nuclei; however, the energy per nucleon range was limited. The abundance for the iron-group nuclei mentioned above is consistent with the present solar spectroscopic abundance estimates. Subject headings: abundances, cosmic-ray abundances, solar
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 1973
- DOI:
- 10.1086/151986
- Bibcode:
- 1973ApJ...180..583B