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M. Schnell, D. W. Savin (Columbia Astrophysics Laboratory, USA), C. Brandau (Gesellschaft für Schwerionenforschung, Germany), A. Müller, S. Schippers (University of Giessen, Germany), A. Wolf (Max Planck Institute for Nuclear Physics, Germany)
Interpreting spectra from cosmics sources requires an accurate understanding of the underlying atomic physics which produces the observed radiation. Of particular importance are reliable ionization balance calculations. For many years a major uncertainty in such calculations, has been acknowledged to lie in the rate coefficients used for the electron-ion recombination process known as dielectronic recombination (DR). This process is the dominant recombination mechanism for most ions in cosmic plasmas.
To address this need, a number of years ago we initiated a laboratory program to measure DR for selected ions in astrophysically relevant L- and M-shell isoelectronic sequence. These measurements provide valuable benchmarks for theorists who can then use the laboratory data to verify the reliability of their theoretical methods. Subsequently they can then more reliably calculate the needed DR data for the remaining unmeasured ions in each benchmarked isoelectronic sequence.
Here we will report recent progress in our ongoing laboratory program to provide the astrophysically needed DR data. Measurements are carried out using the heavy-ion Test Storage Ring located at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany.
This work has been supported in part by NASA, the German Federal Minister for Education and Research, and the German Research Council.
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Bulletin of the American Astronomical Society, 36 #3
© 2004. The American Astronomical Soceity.