Atomic data from the Iron Project
Abstract
We present new calculations for transition probabilities of Fe IV, with much more extensive datasets than heretofore available, for a variety of astrophysical applications. The largescale close coupling Rmatrix calculations yield 1,798 LS bound states with n ≤ 11 and l ≤ 9, and corresponding 138 121 dipole allowed transitions in the form of oscillator strengths f, line strengths S, and Acoeffficients. This represents the largest Rmatrix dataset in LS coupling for any ion under either the Opacity Project or the Iron Project. Through algebraic transformation of the LS multiplets, a total of 712 120 dipole allowed fine structure transitions for Fe IV are obtained. Observed transition energies, whenever available, are used together with the energy independent line strengths to derive the f and the Avalues for improved accuray; the adopted algorithm used calculated energies for the remainder. Present results show significantly better accuracy for the important lowlying states than previous calculations. Monochromatic and mean opacities for Fe IV are computed and compared with those obtained using the Opacity Project data. We find differences which could have important consequences for several astrophysical applications involving low ionization stages of iron.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 July 2005
 DOI:
 10.1051/00046361:20041885
 arXiv:
 arXiv:astroph/0409202
 Bibcode:
 2005A&A...437..345N
 Keywords:

 atomic processes;
 line: formation;
 radiation mechanisms: thermal;
 radiative transfer;
 ISM: HII regions;
 radio lines: galaxies;
 Astrophysics
 EPrint:
 10 pages, 1 figire, submitted to Astronomy and Astrophysics