- ID:
- ivo://CDS.VizieR/J/ApJ/813/16
- Title:
- Fe^7+^ ionization cross section
- Short Name:
- J/ApJ/813/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have measured electron impact ionization for Fe^7+^ from the ionization threshold up to 1200eV. The measurements were performed using the TSR heavy ion storage ring. The ions were stored long enough prior to measurements to remove most metastables, resulting in a beam of 94% ground-level ions. Comparing with the previously recommended atomic data, we find that the Arnaud & Raymond (1992ApJ...398..394A) cross section is up to about 40% larger than our measurement, with the largest discrepancies below about 400eV. The cross section of Dere (2007, J/A+A/466/771) agrees to within 10%, which is about the magnitude of the experimental uncertainties. The remaining discrepancies between our measurement and the Dere calculations are likely due to shortcomings in the theoretical treatment of the excitation-autoionization contribution.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/441/3127
- Title:
- FeI oscillator strengths for Gaia-ESO
- Short Name:
- J/MNRAS/441/3127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Gaia-ESO Public Spectroscopic Survey (GES) is conducting a large-scale study of multi-element chemical abundances of some 100000 stars in the Milky Way with the ultimate aim of quantifying the formation history and evolution of young, mature and ancient Galactic populations. However, in preparing for the analysis of GES spectra, it has been noted that atomic oscillator strengths of important FeI lines required to correctly model stellar line intensities are missing from the atomic data base. Here, we present new experimental oscillator strengths derived from branching fractions and level lifetimes, for 142 transitions of FeI between 3526 and 10864{AA}, of which at least 38 are urgently needed by GES. We also assess the impact of these new data on solar spectral synthesis and demonstrate that for 36 lines that appear unblended in the Sun, Fe abundance measurements yield a small line-by-line scatter (0.08dex) with a mean abundance of 7.44dex in good agreement with recent publications.
- ID:
- ivo://CDS.VizieR/J/A+A/606/A127
- Title:
- FeI photoionization cross sections and ECS
- Short Name:
- J/A+A/606/A127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Iron is a major contributor to the opacity in the atmospheres of late-type stars, as well as a major contributor to the observed lines in their visible spectrum. Iron lines are commonly used to derive basic stellar parameters from medium/high resolution spectroscopy, that is, spectroscopy which shows metal content, effective temperature, and surface gravity. Here we present large R-matrix calculations for photoionization cross sections and electron impact collision strengths.
- ID:
- ivo://CDS.VizieR/J/ApJS/215/23
- Title:
- FeI radiative lifetime and branching fractions
- Short Name:
- J/ApJS/215/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New radiative lifetimes, measured to +/-5% accuracy, are reported for 31 even-parity levels of Fe I ranging from 45061cm^-1^ to 56842cm^-1^. These lifetimes have been measured using single-step and two-step time-resolved laser-induced fluorescence on a slow atomic beam of iron atoms. Branching fractions have been attempted for all of these levels, and completed for 20 levels. This set of levels represents an extension of the collaborative work reported in Ruffoni et al. (2013ApJ...779...17R; 2014, J/MNRAS/441/3127). The radiative lifetimes combined with the branching fractions yields new oscillator strengths for 203 lines of Fe I. Utilizing a 1D-LTE model of the solar photosphere, spectral syntheses for a subset of these lines which are unblended in the solar spectrum yields a mean iron abundance of <log[{epsilon}(Fe)]>=7.45+/-0.06.
- ID:
- ivo://CDS.VizieR/J/MNRAS/391/1828
- Title:
- FeIV energy levels & transition prob.
- Short Name:
- J/MNRAS/391/1828
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Multiconfiguration Dirac-Hartree-Fock electric quadrupole (E2) and magnetic dipole (M1) transition probabilities are reported for transitions between levels of 3d^5^ in [FeIV]. The accuracy of the ab initio energy levels and the agreement in the length and velocity forms of the line strength for the E2 transitions are used as indicators of accuracy. The present E2 and M1 transition probabilities are compared with earlier Breit-Pauli results and other theories. An extensive set of transition probabilities with indicators of accuracy are reported in tables A1 and A2. Recommended values of A(E2)+A(M1) are listed in table A3.
- ID:
- ivo://CDS.VizieR/J/A+A/437/345
- Title:
- Fe IV radiative transition probabilities
- Short Name:
- J/A+A/437/345
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new calculations for transition probabilities of FeIV, with much more extensive datasets than heretofore available, for a variety of astrophysical applications. The large-scale close coupling R-matrix calculations yield 1798 LS bound states with n<=11 and l<=9, and corresponding 138121 dipole allowed transitions in the form of oscillator strengths f, line strengths S, and A-coefficients. 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 712120 dipole allowed fine structure transitions for FeIV 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 accuracy; 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 FeIV 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.
247. FeIX energy levels
- ID:
- ivo://CDS.VizieR/J/ApJ/740/L52
- Title:
- FeIX energy levels
- Short Name:
- J/ApJ/740/L52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New calculations of the energy levels, radiative transition rates, and collisional excitation rates of Fe IX have been carried out using the Flexible Atomic Code (FAC; Gu 2003ApJ...582.1241G), paying close attention to experimentally identified levels and extending existing calculations to higher energy levels. For lower levels, R-matrix collisional excitation rates from earlier work have been used. Significant emission is predicted by these calculations in the 5f-3d transitions, which will impact analysis of Solar Dynamics Observatory Atmospheric Imaging Assembly (SDO/AIA) observations using the 94{AA} filter.
- ID:
- ivo://CDS.VizieR/J/A+A/460/331
- Title:
- Fe IX radiative and excitation rates
- Short Name:
- J/A+A/460/331
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we report calculations for energy levels and radiative rates for transitions in Fe IX. The General purpose Relativistic Atomic Structure Package (GRASP) has been adopted for the calculation of energy levels and radiative rates. Energies for the lowest 360 levels, including those from the (1s^2^2s^2^2p^6^) 3s^2^3p^6^, 3s^2^3p^5^3d, 3s3p^6^3d, 3s^2^3p^4^3d^2^, and 3s^2^3p^5^4l configurations of Fe IX, are reported. Additionally, radiative rates, oscillator strengths, and line strengths are reported for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) transitions among these levels. Comparisons are made with the available results in the literature, and the accuracy of the present data is assessed.
- ID:
- ivo://CDS.VizieR/J/A+A/643/A46
- Title:
- Fe2+ K shell mult. photoionization cross sections
- Short Name:
- J/A+A/643/A46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Multiple photoionization cross sections from the K shell are studied for all levels of the Fe^2+^ 3d^6^ configuration. The study shows that the quadruple photoionization leads to the largest cross sections. A large variation in the multiple photoionization cross sections is determined among the levels of the Fe^2+^ 3d^6^ configuration. Main decay branches of radiative and Auger cascades, following the photoionization of the K shell for the ground configuration of the Fe^2+^ ion, are identified. The radiative and Auger cascade is studied by considering transitions among energy levels and subconfigurations. The obtained data for ion yields are compared with previous calculations produced for configuration averages.
- ID:
- ivo://CDS.VizieR/J/A+A/422/731
- Title:
- Fe X Benchmarking atomic data
- Short Name:
- J/A+A/422/731
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the first in a series of papers in which we benchmark recent atomic data available for astrophysical applications. We review various issues related to the completeness and accuracy of both theoretical and experimental data. In this paper, the available experimental and atomic data for Fe X (n=3 configurations) are reviewed and assessed. New collisional and radiative data are calculated to supplement published data. The radiative calculations are done with empirical adjustements that take into account observed wavelengths. Previous line identifications are also reviewed and assessed. Our approach focuses on the brightest spectral lines, and uses both wavelengths and line intensities to assess the line identifications on a quantitative basis. Although many previous line identifications are confirmed, some are rejected (e.g. the coronal line observed at 1582.35{AA}). We confirm previously suggested identifications (e.g. 257.262{AA},1028.02{AA}), and we present new ones, (e.g. the lines of the 3s^2^ 3p^4^ 3d-3s 3p^5^ 3d transition array). In addition, we highlight the presence of blends and we review which spectral lines are best for density diagnostics or for instrument calibration. The theoretical data (line intensities and level lifetimes) are benchmarked against well-calibrated spectroscopic observations of the solar corona and laboratory measurements. The agreement between theoretical and experimental data which we achieve with our new model ion is very good.
