- 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.
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6162. 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/MNRAS/426/2522
- Title:
- FeK lines in Seyfert 1 galaxies
- Short Name:
- J/MNRAS/426/2522
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We construct full broad-band models in an analysis of Suzaku observations of nearby Seyfert 1 active galactic nuclei (AGN) (z<=0.2) with exposures >50ks and with greater than 30000 counts in order to study their iron line profiles. This results in a sample of 46 objects and 84 observations. After a full modelling of the broad-band Suzaku and Swift-Burst Alert Telescope data (0.6-100keV), we find complex warm absorption is present in 59 per cent of the objects in this sample which has a significant bearing upon the derived FeK region parameters. Meanwhile 35 per cent of the 46 objects require some degree of high column density partial coverer in order to fully model the hard X-ray spectrum. We also find that a large number of the objects in the sample (22 per cent) require high velocity, high ionization outflows in the FeK region resulting from FeXXV and FeXXVI. A further four AGN feature highly ionized FeK absorbers consistent with zero outflow velocity, making a total of 14/46 (30%) AGN in this sample showing evidence for statistically significant absorption in the FeK region.
- 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/628/A54
- Title:
- Fe, Mg, Ti in Galactic clusters
- Short Name:
- J/A+A/628/A54
- Date:
- 02 Nov 2021 11:16:10
- Publisher:
- CDS
- Description:
- We test the effects of non-local thermodynamic equilibrium (NLTE) on the spectra of FGK-type stars across a wide range of metallicity and to derive abundance of Fe, Mg, and Ti for a sample of Galactic star clusters. We extend the Payne fitting approach to draw on NLTE and LTE spectral models in order to determine stellar parameters and chemical abundances for the Gaia-ESO benchmark stars. We also analyse the medium-resolution Giraffe spectra of 742 stars in 13 open and globular clusters in the Milky Way galaxy. We show that this approach accurately recovers effective temperatures, surface gravities, and abundances of the benchmark stars and clusters members. The differences between NLTE and LTE stellar parameters are small for the metal-rich stars. However, for metal-poor stars [Fe/H]<-1, the NLTE estimates of Teff, log(g) and [Fe/H] are higher than LTE estimates, and the systematic offset increases with decreasing metallicity. Our LTE measurements of metallicities and abundances in the Galactic clusters are in a good agreement with the earlier literature studies. For the majority of these clusters, our study yields the first estimates of NLTE abundances of Fe, Mg and Ti. The NLTE [Fe/H] are systematically higher, whereas the average NLTE [Mg/Fe] abundance ratios are ~0.15dex lower, compared to LTE. All clusters investigated in this work appear homogeneous in Fe and Ti, with the intra-cluster abundance variations of less then 0.1dex. We confirm large dispersions of [Mg/Fe] ratios for NGC 2808, NGC 4833 and M 15. Our results shows that NLTE analysis change the mean abundance ratios in the clusters, but does not influence the intra-cluster abundance dispersions. Combining the Payne fitting approach with NLTE spectral models as input is a powerful tool for a detailed exploration of the large-scale spectroscopic stellar surveys.
6167. FEPS Photometry Catalog
- ID:
- ivo://irsa.ipac/Spitzer/Catalog/FEPS
- Title:
- FEPS Photometry Catalog
- Short Name:
- FEPS Photometry
- Date:
- 01 Oct 2018 20:27:17
- Publisher:
- NASA/IPAC Infrared Science Archive
- Description:
- The Formation and Evolution of Planetary Systems (FEPS) Spitzer Legacy program was designed to char- acterize the evolution of circumstellar gas and dust around solar- type stars between ages of 3 Myr and 3 Gyr. To achieve these goals, FEPS obtained spectrophotometric observations with the Spitzer Space Telescope for a sample of 328 stars (see Meyer et al. 2006 for a description of the sample). The observing strategy was to measure the spectral energy distribution (SED) between wavelengths of 3.6 and 70 um with IRAC and MIPS photometry, and between 8 and 35 um with low-resolution IRS spectra.
- ID:
- ivo://CDS.VizieR/J/A+A/606/A50
- Title:
- Fe-rich silicate analogues mass absorption coeff.
- Short Name:
- J/A+A/606/A50
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To model the cold dust emission observed in the diffuse interstellar medium, in dense molecular clouds or in cold clumps that could eventually form new stars, it is mandatory to know the physical and spectroscopic properties of this dust and to understand its emission. This work is a continuation of previous studies aiming at providing astronomers with spectroscopic data of realistic cosmic dust analogues for the interpretation of observations. The aim of the present work is to extend the range of studied analogues to iron-rich silicate dust analogues. Ferromagnesium amorphous silicate dust analogues were produced by a sol-gel method with a mean composition close to Mg_1-x_Fe_x_SiO_3_ with x=0.1, 0.2, 0.3, 0.4. Part of each sample was annealed at 500{deg}C for two hours in a reducing atmosphere to modify the oxidation state of iron. We have measured the mass absorption coefficient (MAC) of these eight ferromagnesium amorphous silicate dust analogues in the spectral domain 30-1000um for grain temperature in the range 10-300K and at room temperature in the 5-40um range. The MAC of ferromagnesium samples behaves in the same way as the MAC of pure Mg-rich amorphous silicate samples. In the 30-300K range, the MAC increases with increasing grain temperature whereas in the range 10-30K, we do not see any change of the MAC. The MAC cannot be described by a single power law in {lambda}^-{beta}^. The MAC of the samples does not show any clear trend with the iron content. However the annealing process has, on average, an effect on the MAC that we explain by the evolution of the structure of the samples induced by the processing. The MAC of all the samples is much higher than the MAC calculated by dust models. The complex behavior of the MAC of amorphous silicates with wavelength and temperature is observed whatever the exact silicate composition (Mg vs. Fe amount). It is a universal characteristic of amorphous materials, and therefore of amorphous cosmic silicates, that should be taken into account in astronomical modeling. The enhanced MAC of the measured samples compared to the MAC calculated for cosmic dust model implies that dust masses are overestimated by the models.
- ID:
- ivo://nasa.heasarc/fermi2favs
- Title:
- Fermi All-Sky Variability Analysis Second Catalog of Flaring Gamma-Ray Sources
- Short Name:
- FERMI2FAVS
- Date:
- 27 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Fermi All-sky Variability Analysis (FAVA) is an analysis technique that searches for flaring sources in data collected by the Large Area Telescope (LAT) onboard NASA's Fermi Gamma-ray Space Telescope. It uses a photometric approach to blindly search for flares over the entire sky, and a likelihood analysis to precisely locate them and to measure their spectra. This catalog contains the flares and sources detected by running FAVA over the first 7.4 years of Fermi mission, from Modified Julian Date (MJD) 54682 (2008-08-04) to 57391 (2016-01-04). The analysis has been run in weekly time bins and in two independent energy bands, 100-800 MeV and 0.8-300 GeV. The detection threshold applied to the catalog flares is equivalent to 6 sigma (pre trials). The sources in the 2FAV are identified as clusters of flares. Their position and the corresponding error are derived from a weighted average of the best localized flares in the cluster. Likely gamma-ray counterparts, based on positional coincidence, are provided for the sources. This database table was first ingested by the HEASARC in July 2017 using electronic data obtained from the Fermi Science Support Center (FSSC). That data is available at <a href="http://fermi.gsfc.nasa.gov/ssc/data/access/lat/fava_catalog/">http://fermi.gsfc.nasa.gov/ssc/data/access/lat/fava_catalog/</a>. This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/J/A+A/557/A100
- Title:
- Fermi and Swift GRBs E_peak_-E_iso_ relation
- Short Name:
- J/A+A/557/A100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used a sample of gamma-ray bursts (GRBs) detected by Fermi and Swift to reanalyze the correlation discovered by Amati et al. (2002A&A...390...81A) between E_pi_, the peak energy of the prompt GRB emission, and E_iso_, the energy released by the GRB assuming isotropic emission. This correlation has been disputed by various authors, and our aim is to assess whether it is an intrinsic GRB property or the consequence of selection effects. We constructed a sample of Fermi GRBs with homogeneous selection criteria, and we studied their distribution in the E_pi_-E_iso_ plane. Our sample is made of 43 GRBs with a redshift and 243 GRBs without a redshift. We show that GRBs with a redshift follow a broad E_pi_-E_iso_ relation, while GRBs without a redshift show several outliers. We use these samples to discuss the impact of selection effects associated with GRB detection and with redshift measurement.