Abundance Modification by the Diamagnetic Effect

Abstract

Abundances of elements with first ionization potential (FIP) less than 10 eV in the corona and solar wind are augmented relative to the solar photosphere. This enhancement has been found to be independent of both mass and charge. We emphasize two facts that are relevant to this problem: (1) Only elements with eV are FIP ! 10 already ionized in the chromosphere, while in the corona, all elements are ionized. (2) It is known that diverging magnetic field structures anchored in the photosphere pass to the chromosphere (e.g., sunspots). Considering these facts, we construct a model in which the combination of the diamagnetic effect and gravity will pump charged particles, but not neutrals, from the chromosphere into the corona, thus producing the observed enhancement of low-versus high-FIP elements. This charged particle pump is operational irrespective of the existence of other mechanisms that have been proposed previously. Qualitative agreement is obtained with observed abundance ratios in the Sun and several stars.

The Coronal Metallicity of the Intermediate Activity Dwarf ξ Bootis A

“…The anomalies are widely know as the "" FIP e †ect ÏÏ because they appear to relate primarily to the Ðrst ionization potential (FIP) of elements, low FIP eV) elements being ([10 enhanced relative to high FIP eV) elements by (Z10 varying amounts but with average enhancements factors of about 3È4. The FIP e †ect remains somewhat of a mystery, and, while several plausible explanations have been put forward (e.g., Feldman 1992 ;Meyer 1996 ;Peter & Eckart 1998 ;Steinitz & Kuno † 1999), there are as yet no widely accepted models to explain the variety of observations.…”