Cool Stars 14 - Submitted Abstract # 226
This version created on 05 October 2006

The Solar Oxygen Problem:  Crisis, Catastrophe, or Opportunity?


Thomas Ayres, University of Colorado (CASA)

Recent attempts to revise the solar oxygen abundance sharply downward
have been met with some dismay--if not also outright hostility--by the
helioseismology community;  because low-O would ruin the previous
excellent agreement between theoretical descriptions of the internal
stratification of the Sun and exquisitely measured seismic oscillation
patterns at the surface.  Although the new "3-D" analyses of the
visible atomic oxygen lines treat the dynamics and thermal rugosity of
the photosphere better than traditional 1-D models, they still are
beset by the usual uncertainties:  blending, continuum placement, NLTE
effects, poorly known atomic parameters, etc.  There also is the more
fundamental question--often glossed over by the convection
modelers--whether the time dependent 3-D thermal structure truly is an
appropriate replica of the real photosphere, since the simulations
must skimp on physical detail--mainly the radiation transport--to
accommodate the difficult multidimensional hydrodynamics.  Here I
compare predictions of 3-D snapshots from the CO5BOLD collaboration
to:  (1) calibrated measurements of Ca II H and K, and subordinate
8542 line;  (2) center-limb observations of the visible continuum;
and (3) spectra and intensity fluctuation maps of infrared CO lines.
These experiments test the accuracy of the thermal model, and as a
byproduct provide an independent way to check the oxygen abundance.
Initial results point to possible deficiencies of the convection model
in the mid photosphere, and favor a higher oxygen abundance (from CO)
than derived from contemporary 3-D modeling of visible O I lines.

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