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Needs for Atomic Data for Quantitative Analysis of Stellar Spectra

Published online by Cambridge University Press:  30 March 2016

B. Baschek
B. Baschek*
Affiliation:
Institute für Theoretische Astrophysik der Universität, Im Neuenheimer Feld, D-6900 Heidelberg

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The goal of a quantitative analysis of a stellar spectrum is to derive the physical and chemical state of the stellar atmosphere, i.e. by definition the region emitting the spectrum. Of particular interest are the element abundances, they have to be determined together with the temperatures and densities (pressures) in the atmosphere. A detailed analysis usually is an iterative procedure: a model atmosphere is constructed from reasonable starting values of the parameters (effective temperature, surface gravity, element abundances,...) and used to calculate a theoretical, “synthetic” spectrum. By comparing the observed with the theoretical spectrum, improved stellar parameters are gained for the next iteration step.

Ideally, all atomic data entering the analysis should be known with sufficient accuracy, i.e. errors in the analysis should be due to uncertainties in the assumptions of the models, in the treatment of the velocity fields etc., and not due to insufficient atomic data. In the last decade, the ultraviolet portion of the spectrum below λ ≲ 3200 Å has become accessible by satellites such as Copernicus and the International Ultraviolet Explorer (IUE) with high spectral resolution. Studies of stellar spectra in this new range have revealed the needs for a large amount of atomic data required for the analyses.

Type
Joint Commission Meetings
Information
Highlights of Astronomy , Volume 6 , 1983 , pp. 781 - 787
Copyright
Copyright © Reidel 1983

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