Atomic Data and Spectral Line Intensities for S xi

Abstract

Electron impact collision strengths, energy levels, oscillator strengths, and spontaneous radiative decay rates are calculated for S xi. The configurations included are 2s 2 2p 2 , 2s2p 3 , 2p 4 , 2s 2 2p3l, and 2s 2 2p4l (l ¼ s, p, d ), giving rise to 72 fine-structure levels in intermediate coupling. Collision strengths are calculated at five incident energies, 32, 60, 90, 120, and 150 ryd. Excitation rate coefficients are calculated as a function of electron temperature by assuming a Maxwellian electron velocity distribution. Using the excitation rate coefficients and the radiative transition rates, statistical equilibrium equations for level populations are solved. The effects of resonances, proton rates, photoexcitation, and cascades on level populations have been investigated. The predicted S xi line intensities are compared with EUV and UV observations of the quiet and active Sun.

R-matrix electron-impact excitation data for astrophysically abundant sulphur ions

“…additional CI configuration S IX 2s x 2p y (x + y = 6) 2s 2 2p 3 4l, 2s2p 4 3s (except for 5 P and 3 P) 2s 2 2p 3 3l 2s2p 4 {3p, 3d, 4l} 2s2p 4 3s ( 5 P and 3 P) 2p 5 {3, 4}l 2s 2 2p 2 3l x 3l ′y (x + y = 2) S X 2s x 2p y (x + y = 5) 2s2p 3 {3, 4}l 2s 2 2p 2 3l 2s 2 2p 2 4l 2s2p 3 3s ( 6 S, 4 S and 4 D) 2p 4 {3, 4}l 2s2p 3 3p ( 6 P and 4 P) S XI 2s x 2p y (x + y = 4) 2p 3 3p ( 1 D, 1 S) 2s 2 2p3l, 2s2p 2 3l 2p 3 3p ( 3 S, 1,3 P/D/F) 2s 2 2p4l, 2p 3 3s 2s2p 2 4l 2p 3 3p (except for 1 D, 1 S) 2p 3 4l 2p 3 3d (except for 3 S, 1,3 P/D/F) S XII 2s x 2p y (x + y = 3) 2p 2 3{4}l, 2s3s3l 2s 2 3{4}l, 2s2p3{4}l 2p3s3l, 2s3p 2 , 2s3d 2 tion and those of the 2p 4 configuration, the present results are systematically higher than NIST data by 1-2%. The present AS result shows an excellent agreement (less than 0.5%) with the result of Landi & Bhatia (2003) for all levels of the n=3 configurations. However, both sets of results are systematically higher than the NIST data for the levels of n=2 complex, those of Landi & Bhatia (2003) more-so than the present which are within 2% (excluding the 5 S 2 ).…”

“…For S 10+ , the newest excitation data are attributed to be the work of Landi & Bhatia (2003), who have extended a previous (n=3) DW calculation to include n=4 configurations (viz 2s 2 2p4l ′ , l ′ =s, p and d). Their results have been incorporated into astrophysical modelling codes, e.g.…”

Signatures of Slow Solar Wind Streams from Active Regions in the Inner Corona

“…For both cases the authors found the plasma temperature component peaked near 1 MK. Landi and Young (2009) reported on a cold, bright portion of an AR observed by the EIS instrument. The emitting region was characterized by a large maximum at log T ≈ 5.6, corresponding to transition region temperatures, and a broad tail in the DEM distribution extending to higher temperatures.…”

Influence of the Nonlinearity Parameter on the Solar Wind Sub-Ion Magnetic Energy Spectrum: Flr–landau Fluid Simulations

“…In a magnetized weakly collisional plasma, each of the gyrotropic heat fluxes is modeled as q ∼ b · ∇ T where T refers to the corresponding temperature fluctuations (Spitzer & Härm 1953) Differently, in the collisionless regime, the heat flux scales like v th T (Hollweg 1974), where v th is the associated thermal velocity. Transition between these two regimes in the solar wind was re-cently studied both from observational data ) and numerical simulations (Landi et al 2014). The low-frequency linear kinetic theory reproduces this scaling, but the relation involves a Hilbert transform along the equilibrium magnetic field lines, making the system dissipative as a consequence of Landau damping (see e.g.…”