Related papers: A New Multiplet Table for Fe
The lack of FeVII lines in PG1159 stars had led to the conclusion that in some objects iron must be strongly depleted. We have now detected FeX lines in FUSE spectra of the very hottest PG1159 stars Teff=150,000 - 200,000 K; RXJ2117.1+3412,…
Improved collisions strengths for the mid-infrared and optical transitions in Ne V are presented. Breit-Pauli R-Matrix calculations for electron impact excitation are carried out with fully resolved near-threshold resonances at very low…
We study the influence of convection on the asymmetries and Doppler shifts of Fe I spectral lines in the metal-poor red giant HD 122563. To this end, we compute theoretical Fe I line shifts and line bisectors using 3D hydrodynamical model…
We report measurements of the isotope shifts of the 3d6 4s2 a 5D3 - 3d6 4s4p z 5F4o FeI resonance line at 373.7 nm between all four stable isotopes 54Fe, 56Fe, 57Fe and 58Fe, as well as the complete hyperfine structure of that line for…
Archived high-resolution X-ray spectra in the 13~\AA\ to 22~\AA\ range from the Flat Crystal Spectrometer (FCS), an instrument on the Solar Maximum Mission operating in the 1980s, are analyzed with reference to nonflaring active regions,…
New calculations of radiative rates and electron impact excitation cross sections for Fe XI are used to derive emission line intensity ratios involving 3s^23p^4 - 3s^23p^33d transitions in the 180-223 A wavelength range. These ratios are…
We report new experimental hyperfine structure (HFS) constants of neutral and singly ionized scandium (Sc I and Sc II). We observed spectra of Sc-Ar and Sc-Ne hollow cathode discharges in the region 200-2500 nm (50,000-4000 cm$^{-1}$) using…
To study the structure of spatially unresolved features of the solar photosphere, we calculated the Stokes profiles of seven photospheric iron lines using two-dimensional nonstationary MHD models of solar granulation for various amounts of…
The identifications of Fe VII emission lines in the wavelength range 193-197 {\AA} are discussed in the light of new measurements of laboratory spectra and atomic data calculations. This region is of importance to studies of solar spectra…
Relativistic atomic structure calculations for electric dipole E1, electric quadrupole E2 and magnetic dipole M1 transition probabilities among the first 80 fine-structure levels of Fe VI, dominated by configurations 3d^3, 3d^24s, and…
We provide a discussion of the density and photoexcitation sensitivity of the X-ray spectra of Fe L-shell ions (Fe XVII-Fe XXIV) calculated with the Livermore X-ray Spectral Synthesizer, a suite of IDL codes that calculates spectral models…
Using the Livermore X-ray Spectral Synthesizer, which calculates spectral models of highly charged ions based on HULLAC atomic data, we investigate the temperature, density, and photoexcitation dependence of the I(11.92 A)/I(11.77 A) line…
Optical transitions of highly charged ions can be very sensitive to hypothetical beyond-the-Standard-Model phenomena. Those near the $5s-4f$ level crossing, where the $5s$ and $4f$ are degenerate are especially promising. We present…
Using the photon-ion merged-beams technique at a synchrotron light source, we have measured relative cross sections for single and up to five-fold photoionization of Fe$^{2+}$ ions in the energy range 690--920 eV. This range contains…
The He I infrared (IR) triplet at 10830 \AA is known as an activity indicator in solar-type stars and has become a primary diagnostic in exoplanetary transmission spectroscopy. He I lines are a tracer of the stellar extreme-ultraviolet…
Multiconfiguration Dirac-Hartree-Fock electric quadrupole (E2) and magnetic dipole (M1) transition probabilities are reported for transitions between levels of 3d^5 in [Fe IV]. The accuracy of the ab initio energy levels and the agreement…
Energy levels, Land\'{e} $g$-factors and radiative lifetimes are reported for the lowest 182 levels of the 3d$^4$, 3d$^3$4s and 3d$^3$4p configurations of Fe~V, Co~VI and Ni~VII. Additionally, radiative rates ($A$-values) have been…
In the near ultraviolet (NUV) part of the solar spectrum, there are several Fe I lines with very broad profiles, typical of chromospheric lines. These lines are largely unexplored due to the lack of high-resolution data in this region. This…
We present observations of VUV transitions between doubly excited sextet states in O IV, F V and Ne VI. Spectra were produced by collisions of an O+, (FH)+ and Ne+ beam with a solid carbon target. Some observed lines are assigned to the…
We report on the results of 18 observations of the core, or peak, of the Fe K emission line at $\sim 6.4$ keV in 15 Seyfert I galaxies using the {\it Chandra} High Energy Grating (HEG). These data afford the highest precision measurements…