Abstract
Systematic anomalies that seem to follow the first ionisation
potential (FIP) of the minor, heavy elements at the sun, have been
found when comparing the observed elemental abundances in the upper
solar atmosphere with the photospheric abundances.
In this work we study whether gravitational settling of these minor
elements in a well mixed chromosphere can explain these FIP dependent
abundance variations.
We conclude that this mechanism yields abundance variations that can
be compared with the observed variations if the ionisation degree of
elements with FIP less than 10eV is high and the
ionisation degree of the hydrogen background and of oxygen
(FIP=13.6eV) is low.