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Astron. Astrophys. 350, 672-679 (1999)


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Effects of line asymmetries on the determination of solar internal structure

M.C. Rabello-Soares 1, J. Christensen-Dalsgaard 1,2, C.S. Rosenthal 3 and M.J. Thompson 4

1 Teoretisk Astrofysik Center, Danmarks Grundforskningsfond 8000 Aarhus C, Denmark (csoares@obs.aau.dk)
2 Institut for Fysik og Astronomi, Aarhus Universitet, 8000 Aarhus C, Denmark (jcd@obs.aau.dk)
3 Institute of Theoretical Astrophysics, University of Oslo, Blindern, 0315 Oslo, Norway (colin.rosenthal@astro.uio.no)
4 Astronomy Unit, Queen Mary and Westfield College, London E1 4NS, UK (M.J.Thompson@qmw.ac.uk)

Received 23 June 1999 / Accepted 5 August 1999

Abstract

Despite the strong evidence that the peaks in the spectrum of solar oscillations are asymmetric, most determinations of mode frequencies have been based on fits of symmetric Lorentzian profiles to the Fourier or power spectra of oscillation time strings. The systematic errors resulting from neglecting the line asymmetry could have serious effects on inversions for the solar internal structure and rotation. Here we analyse artificial data based on simple models of the intrinsic line asymmetry, using GONG mode parameters with asymmetries found by one of us (Rosenthal 1998b). By fitting Lorentzians to the resulting spectra, we estimate the likely properties of the errors introduced in the frequencies. We discuss whether these frequency shifts have a form similar to the near-surface layers uncertainties and are therefore suppressed in the solar structure inversion. We also estimate directly their contribution, if any, in the solar sound-speed and density determinations using the SOLA technique.

Key words: Sun: oscillations – Sun: interior

Send offprint requests to: M.C. Rabello-Soares

© European Southern Observatory (ESO) 1999

Online publication: October 4, 1999

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