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Astron. Astrophys. 359, 743-754 (2000)


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Line formation in solar granulation

II. The photospheric Fe abundance

M. Asplund 1, Å. Nordlund 2, R. Trampedach 3 and R.F. Stein 3

1 NORDITA, Blegdamsvej 17, 2100 Copenhagen O, Denmark
2 Astronomical Observatory, NBIfAFG, Juliane Maries Vej 30, 2100 Copenhagen O, Denmark
3 Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48823, USA

Received 24 January 2000 / Accepted 4 May 2000

Abstract

The solar photospheric Fe abundance has been determined using realistic ab initio 3D, time-dependent, hydrodynamical model atmospheres. The study is based on the excellent agreement between the predicted and observed line profiles directly rather than equivalent widths, since the intrinsic Doppler broadening from the convective motions and oscillations provide the necessary non-thermal broadening. Thus, three of the four hotly debated parameters (equivalent widths, microturbulence and damping enhancement factors) in the center of the recent solar Fe abundance dispute regarding Fe I lines no longer enter the analysis, leaving the transition probabilities as the main uncertainty. Both Fe I (using the samples of lines of both the Oxford and Kiel studies) and Fe II lines have been investigated, which give consistent results: [FORMULA] and [FORMULA] Also the wings of strong Fe I lines return consistent abundances, [FORMULA] but due to the uncertainties inherent in analyses of strong lines we give this determination lower weight than the results from weak and intermediate strong lines. In view of the recent slight downward revision of the meteoritic Fe abundance [FORMULA], the agreement between the meteoritic and photospheric values is very good, thus appearingly settling the debate over the photospheric Fe abundance from Fe I lines.

Key words: convection – hydrodynamics – line: formation – Sun: abundances – Sun: granulation – Sun: photosphere

Present address: Uppsala Astronomical Observatory, Box 515, 751 20 Uppsala, Sweden

Send offprint requests to: M. Asplund (martin@astro.uu.se)

© European Southern Observatory (ESO) 2000

Online publication: July 7, 2000

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