Sven Wedemeyer, Hartmut Holweger
(Institut für Theoretische Physik und Astrophysik, Universität Kiel, D-24098 Kiel, Germany),
Matthias Steffen
(Astrophysikalisches Institut Potsdam, D-14482 Potsdam, Germany)
Silicon as a cosmic reference element: a reassessment of the solar Si abundance
Silicon is an important reference element for comparing
various types of cosmic matter with the Sun. The most widely used sources of
solar (photospheric) abundances, the compilation by Anders & Grevesse (1989)
and its updates (e.g. Grevesse & Sauval 1998), are based on standard
abundance analyses employing 1D solar models and, in most cases, assuming LTE.
We report NLTE calculations for Si and a first attempt to determine
the effect of horizontal temperature inhomogeneities associated with
convection on the photospheric abundance of Si.
We combine the result with that obtained previously for O and Fe
(Aellig et al. 1999; Schnabel et al. 1999) and compare the photospheric
Si/Fe, Si/O and Si/H abundance ratios with literature data for meteorites,
the corona and solar wind, energetic particles and galactic B stars
and H,II regions.
References:
Aellig M.R., Holweger H., Bochsler P., et al., 1999, Solar Wind Nine, AIP Conf. Proc. Vol. 471, 255
Anders E., Grevesse N., 1989, Geochim. Comochim. Acta 53, 197
Grevesse N., Sauval A.J., 1998, Space Sci. Rev. 85, 161
Schnabel R., Kock M., Holweger H., 1999, A&A 342, 610
See also the publication Wedemeyer, S. 2001 (A&A 373, 998-1008).
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