Speaker
Martin Asplund
(Australian National University)
Description
In the Sun, the convection zone reaches up to the solar atmosphere
and can thus directly influence the emergent spectrum. Traditionally,
the effects of convection has been modelled with the local mixing
length theory in 1D hydrostatic model atmospheres for
stars like the Sun. In a different approach, we have performed
realistic time-dependent, 3D, radiative-hydrodynamical simulations
of the outer layers of the solar convection zone, including the atmosphere.
Both the different mean stratification and the presence of atmospheric
inhomogeneities in 3D impact the spectral line formation.
We have applied this 3D solar model atmosphere to the problem of the
solar chemical composition while adopting the best possible atomic
and molecular line data and taking into account departures from LTE
in the line formation when necessary. The inferred C, N, O and Ne
abundances are all significantly lower than estimated from previous
1D modelling by 0.2-0.3 dex. These results have significant implications
for a range of topics in contemporary astrophysics, including causing
a severe headache for helioseismology. In this review talk I will present an
overview of our analysis, give arguments why our results are trustworthy
and discuss some of their ramifications.
Author
Martin Asplund
(Australian National University)
