Atomic data from the Iron Project LIX. New radiative transition probabilities for Fe IV including fine structure

By S. Nahar, A. Pradhan. 2004

185 citations recorded by the source corpus.

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 large-scale close coupling R -matrix calculations yield 1,798 LS bound states with $n \leq 11$ and $l \leq 9$, and corresponding 138 121 dipole allowed transitions in the form of oscillator strengths f , line strengths S , and A-coeffficients. This represents the largest R -matrix 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 A -values for improved accuray; the adopted algorithm used calculated energies for the remainder. Present results show significantly better accuracy for the important low-lying 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.

Subfields: Atomic and Molecular Physics, and Optics, Mechanics of Materials, Radiation

View Paper: https://www.semanticscholar.org/paper/912e8f15b1829f3f86c3860b6986cb447104c958

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Atomic and Molecular Physics, and Optics

1. G. D. Zanna
2. Peter R. Young
3. K. Dere
4. E. Landi
5. Helen E. Mason
6. M. Carlsson
7. J. C. Raymond
8. A. C. Fabian

In Mechanics of Materials

1. G. D. Zanna
2. Peter R. Young
3. K. Dere
4. E. Landi
5. Helen E. Mason
6. M. Carlsson
7. J. C. Raymond
8. A. C. Fabian

In Radiation

1. K. Dere
2. Peter R. Young
3. E. Landi
4. G. D. Zanna
5. M. Carlsson
6. A. C. Fabian
7. Helen E. Mason
8. C. Reynolds

Citations in the corpus

• The Accretion Disk Wind in the Black Hole GRO J1655–40 (2008, methodology): “The lines were identified based on the wavelengths given in standard spectroscopic references including Verner, Verner, & Ferland (1996), the NIST Atomic Spectra Database, and Nahar & Pradhan (1999).”
• THE QUASAR OUTFLOW CONTRIBUTION TO AGN FEEDBACK: VLT MEASUREMENTS OF SDSS J0318-0600 (2009, methodology): “Bautista et al. (1996) constructed a detailed 142 level model of the Ni ii system for spectral analysis, which was updated with improved atomic data by Bautista (2004).”
• MOCASSIN: a fully three-dimensional Monte Carlo photoionization code (2002, background): “Currently, radiative and dielectronic recombination rates are still highly uncertain or unavailable for some ions; recent efforts to improve the situation have been reviewed by Nahar & Pradhan (1999) and Nahar (2000).”
• Approximations for radiative cooling and heating in the solar chromosphere (2012, methodology): “Collisional excitation rates are from Meléndez et al. (2007) extrapolated beyond the tabulated temperature range of 3000 K to 38 000 K using Burgess & Tully (1992).”
• A non-LTE study of neutral and singly-ionized iron line spectra in 1D models of the Sun and selected late-type stars ? (2011, background): “The latter assumption can be verified for the single forbidden transition of Fe i, a 5D–a 5F, for which the calculations of Pelan & Berrington (1997) in the IRON Project lead to Υ = 0.98 at T = 4000 K.”
• CHIANTI - An atomic database for Emission Lines. Version 8 (2015, methodology): “The A-values for the allowed transitions are taken from Ballance & Griffin (2008), while those for the forbidden transitions are retained from the previous CHIANTI model, which originated from Chen & Pradhan (2000).”