- ID:
- ivo://CDS.VizieR/J/ApJ/808/174
- Title:
- FeII radiative transition rates
- Short Name:
- J/ApJ/808/174
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present extensive calculations of radiative transition rates and electron impact collision strengths for FeII. The data sets involve 52 levels from the 3d^7^, 3d^6^4s, and 3d^5^4s^2^ configurations. Computations of A-values are carried out with a combination of state-of-the-art multiconfiguration approaches, namely the relativistic Hartree-Fock, Thomas-Fermi-Dirac potential, and Dirac-Fock methods, while the R-matrix plus intermediate coupling frame transformation, Breit-Pauli R-matrix, and Dirac R-matrix packages are used to obtain collision strengths. We examine the advantages and shortcomings of each of these methods, and estimate rate uncertainties from the resulting data dispersion. We proceed to construct excitation balance spectral models, and compare the predictions from each data set with observed spectra from various astronomical objects. We are thus able to establish benchmarks in the spectral modeling of [FeII] emission in the IR and optical regions as well as in the UV FeII absorption spectra. Finally, we provide diagnostic line ratios and line emissivities for emission spectroscopy as well as column densities for absorption spectroscopy.
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- ID:
- ivo://CDS.VizieR/J/A+A/377/361
- Title:
- Fe II transition probabilities and loggf
- Short Name:
- J/A+A/377/361
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report measurements of the relative intensities of 81 emission lines of Fe II between 160nm and 350nm (62168cm^-1^ to 28564cm^-1^) from 4 levels by high resolution Fourier transform spectrometry, using a Penning discharge lamp as light source. These relative intensities have been used to determine the line branching fractions, which have then been combined with accurate experimental radiative lifetime measurements reported recently to give absolute transition probabilities and oscillator strengths for 81 lines. The accuracy of these f-values is compared with other previous experimental measurements, and with theoretical values. The new transition probabilities will allow accurate determinations of Fe II abundances in a wide variety of astrophysical objects.
- ID:
- ivo://CDS.VizieR/J/A+A/415/993
- Title:
- FeII, ZNI and SI abundances on halo stars
- Short Name:
- J/A+A/415/993
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The table gives equivalent widths (in m{AA}) for 19 FeII lines, two ZnI lines, and four SI lines, as measured in high resolution VLT/UVES spectra of 34 metal-poor, main sequence and subgiant, halo stars.
- ID:
- ivo://CDS.VizieR/J/A+AS/129/41
- Title:
- Fe I line shifts in the Sun
- Short Name:
- J/A+AS/129/41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Central wavelengths measured in the FTS disc-centre spectrum, in the FTS flux spectrum, rest wavelengths, excitation potentials, transition probabilities (log(gfs)) and line equivalent widths at the centre of the disc when available (from Moore et al. 1966 (The Solar Spectrum 2935{AA} to 8770{AA}, National Bureau of Standards Monograph 61) and compiled by A. D. Wittmann, private communication). An asterisk in the equivalent width means that the line has a blend.
- ID:
- ivo://CDS.VizieR/J/ApJ/875/129
- Title:
- FeI lines in NIR spectra of Arcturus & mu Leo
- Short Name:
- J/ApJ/875/129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- For a detailed analysis of stellar chemical abundances, high-resolution spectra in the optical have mainly been used, while the development of near-infrared (NIR) spectrograph has opened new wavelength windows. Red giants have a large number of resolved absorption lines in both the optical and NIR wavelengths, but the characteristics of the lines in different wave passbands are not necessarily the same. We present a selection of FeI lines in the z', Y, and J bands (0.91-1.33{mu}m). On the basis of two different lists of lines in this range, the Vienna Atomic Line Database (VALD) and the catalog published by Melendez & Barbuy in 1999 (MB99; Cat. J/ApJS/124/527), we selected sufficiently strong lines that are not severely blended and compiled lists with 107 FeI lines in total (97 and 75 lines from VALD and MB99, respectively). Combining our lists with high-resolution ({lambda}/{Delta}{lambda}=28000) and high signal-to-noise (>500) spectra taken with an NIR spectrograph, WINERED, we present measurements of the iron abundances of two prototype red giants: Arcturus and {mu} Leo. A bootstrap method for determining the microturbulence and abundance together with their errors is demonstrated. The standard deviations of log{epsilon}_Fe_ values from individual FeI lines are significantly smaller when we use the lines from MB99 instead of those from VALD. With the MB99 list, we obtained {xi}=1.20+/-0.11km/s and log{epsilon}_Fe_=7.01+/-0.05dex for Arcturus, and {xi}=1.54+/-0.17km/s and log{epsilon}_Fe_=7.73+/-0.07dex for {mu} Leo. These final values show better agreements with previous values in the literature than the corresponding values we obtained with VALD.
- 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.
- 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.