Cool Stars 14 - Submitted Abstract # 57
This version created on 05 October 2006

Alpha Centauri and the abundance of neon in the local universe


Juergen H.M.M. Schmitt, Hamburg Observatory 
Carolin Liefke, Hamburg Observatory

Recent improvements in the modelling of solar convection and line
formation lead to downward revisions of the solar photospheric
abundances of the lighter elements, which in turn leads to changes in
the radiative opacity of the solar interior and thus to conflicts with
the solar convection zone depth as inferred helioseismic oscillation
frequencies.  An increase of the solar Ne/O abundance has been
proposed as a cure of the problem.  Increased Ne abundances are
typically derived from high-resolution X-ray spectra of stars,
however, practically all of these stars are active stars where
additional effects (IFIP) may operate.  We infer the Ne/O abundance
ratio of Alpha~Cen from X-ray spectra obtained with the XMM-Newton RGS
to provide a reliable reference value for an inactive, solar-like
star.  Three independent, line-based methods are used to obtain robust
Ne/O abundance ratio estimates.  Our results yield a value of 0.28 for
A(Ne)/A(O) in Alpha~Cen, approximately twice the value measured for
the Sun, but still below the average value obtained for other stars.

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