Element abundances in the upper atmospheres of the sun and stars: Update of observational results

Citation
U. Feldman et Jm. Laming, Element abundances in the upper atmospheres of the sun and stars: Update of observational results, PHYS SCR, 61(2), 2000, pp. 222-252
Citations number
172
Categorie Soggetti
Physics
Journal title
PHYSICA SCRIPTA
ISSN journal
02811847 → ACNP
Volume
61
Issue
2
Year of publication
2000
Pages
222 - 252
Database
ISI
SICI code
0281-1847(200002)61:2<222:EAITUA>2.0.ZU;2-T
Abstract
We review observational progress in the determination of element abundances in the solar corona, largely due to the new capabilities offered by the in strumentation on the SOHO satellite. Many new facets to coronal abundance a nomalies with respect to the photosphere are revealed. This includes new re sults on the FIP (First Ionization Potential) Effect, whereby elements with FIP < 10 eV are enriched in the corona by a factor similar to 4 with respe ct to the photosphere, and the first evidence for gravitational settling of heavy elements in the corona. Advances in EUV and X-ray astronomy instrumentation have also yielded the f irst spectra of stellar coronae of sufficient quality to allow element abun dance measurements. We survey these new results and compare the various ste llar cases to the solar corona.