Journalartikel

Jahr der Veröffentlichung: 2002

Seiten: 1098-1107

Zeitschrift: The Astrophysical Journal

Bandnummer: 576

Heftnummer: 2

ISSN: 0004-637X

DOI Link: https://doi.org/10.1086/341810

Verlag: American Astronomical Society

Abstract: 
We have measured resonance strengths and energies for dielectronic recombination (DR) of Fe xix forming Fe xviii via N = 2 --> N' = 2 and N = 2 --> N' = 3 core excitations. All measurements were carried out using the heavy-ion Test Storage Ring at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany. We have also calculated these resonance strengths and energies using two independent, state-of-the-art techniques: the perturbative multiconfiguration Breit-Pauli (MCBP) and multiconfiguration Dirac-Fock ( MCDF) methods. Overall, reasonable agreement is found between our experimental results and theoretical calculations. The most notable discrepancies are for the 3l3l' resonances. The calculated MCBP and MCDF resonance strengths for the n = 3 complex lie, respectively, approximate to47% and approximate to31% above the measured values. These discrepancies are larger than the estimated less than or similar to20% total experimental uncertainty in our measurements. We have used our measured 2 --> 2 and 2 --> 3 results to produce a Maxwellian-averaged rate coefficient for DR of Fe xix Our experimentally derived rate coefficient is estimated to be good to better than 20% for k(B) T(e) greater than or equal to 1 eV. Fe xix is predicted to form in photoionized and collisionally ionized cosmic plasmas at k(B) T(e) >>1 eV. Hence, our rate coefficient is suitable for use in ionization balance calculations of these plasmas. Previously published theoretical DR rate coefficients are in poor agreement with our experimental results. None of these published calculations reliably reproduce the magnitude or temperature dependence of the experimentally derived rate coefficient. Our MCBP and MCDF results agree with our experimental rate coefficient to within approximate to20%.

Harvard-Zitierstil: Savin, D., Kahn, S., Linkemann, J., Saghiri, A., Schmitt, M., Grieser, M., et al. (2002) Dielectronic Recombination of Fe XIX Forming Fe XVIII: Laboratory Measurements and Theoretical Calculations, The Astrophysical Journal, 576(2), pp. 1098-1107. https://doi.org/10.1086/341810

APA-Zitierstil: Savin, D., Kahn, S., Linkemann, J., Saghiri, A., Schmitt, M., Grieser, M., Repnow, R., Schwalm, D., Wolf, A., Bartsch, T., Müller, A., Schippers, S., Chen, M., Badnell, N., Gorczyca, T., & Zatsarinny, O. (2002). Dielectronic Recombination of Fe XIX Forming Fe XVIII: Laboratory Measurements and Theoretical Calculations. The Astrophysical Journal. 576(2), 1098-1107. https://doi.org/10.1086/341810