The FIP Effect and Abundance Anomalies in Late-Type Stellar Coronae

Abstract

“Yes, it will be a long time before people know what I know. How much of iron and other metal there is in the sun and the stars is easy to find out, but anything which exposes our swinishness is difficult, terribly difficult” (Tolstoy 1889).In the solar corona, the abundances of elements appear to differ from the photospheric values in a manner related to the element first ionization potential (FIP): species with FIP ≤ 10 eV are observed to be enhanced relative to the photosphere by factors of ~3−4. The first studies of stellar coronal composition with EUVE suggest that some stars exhibit a solar-like FIP effect, whereas others do not. We briefly review the latest results, and we argue that element abundance anomalies, such as the FIP effect, can provide potentially powerful new coronal diagnostics. Moreover, knowledge of the composition of a stellar corona is crucial for interpreting its spectrum—for understanding its structure and energy balance, and for testing its possible heating mechanisms: We must begin to understand coronal abundance anomalies and the compositions of active stars in order to begin to understand their coronal physics.