  The metallic gas associated with the Beta Pic debris disk is not believed to
be primordial, but arises from the destruction of dust grains. Recent
observations have shown that carbon and oxygen in this gas are exceptionally
overabundant compared to other elements, by some 400 times. We study the origin
of this enrichment under two opposing hypothesis, preferential production,
where the gas is produced with the observed unusual abundance (as may happen if
gas is produced by photo-desorption from C/O-rich icy grains), and preferential
depletion, where the gas evolves to the observed state from an original solar
abundance (if outgassing occurs under high-speed collisions) under a number of
dynamical processes. We include ... ... We find ... ...
