- ID:
- ivo://CDS.VizieR/J/A+A/619/A134
- Title:
- ATHOS. Flux ratio based stellar parameterization
- Short Name:
- J/A+A/619/A134
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The rapidly increasing number of stellar spectra obtained by existing and future large-scale spectroscopic surveys feeds a demand for fast and efficient tools for the spectroscopic determination of fundamental stellar parameters. Such tools should not only comprise customized solutions for one particular survey or instrument, but, in order to enable cross-survey comparability, they should also be capable of dealing with spectra from a variety of spectrographs, resolutions, and wavelength coverages. To meet these ambitious specifications, we developed ATHOS (A Tool for HOmogenizing Stellar parameters), a fundamentally new analysis tool that adopts easy-to-use, computationally inexpensive analytical relations tying flux ratios (FRs) of designated wavelength regions in optical spectra to the stellar parameters effective temperature (Teff), iron abundance ([Fe/H]), and surface gravity (logg). Our Teff estimator is based on FRs from nine pairs of wavelength ranges around the Balmer lines H{beta} and H{alpha}, while for [Fe/H] and logg we provide 31 and 11 FRs, respectively, which are spread between ~4800{AA} and ~6500{AA}; a region covered by most optical surveys. The analytical relations employing these FRs were trained on N=124 real spectra of a stellar benchmark sample that covers a large parameter space of Teff~=4000 to 6500K (spectral types F to K), [Fe/H]~=-4.5 to 0.3dex, and logg~=1 to 5dex, which at the same time reflects ATHOS' range of applicability. We find accuracies of 97K for Teff, 0.16dex for [Fe/H], and 0.26dex for logg, which are merely bounded by finite uncertainties in the training sample parameters. ATHOS' internal precisions can be better by up to 70%. We tested ATHOS on six independent large surveys spanning a wide range of resolutions (R~=2000 to 52000), amongst which are the Gaia-ESO and the SDSS/SEGUE surveys. The exceptionally low execution time (<30ms per spectrum per CPU core) together with a comparison to the literature parameters showed that ATHOS can successfully achieve its main objectives, in other words fast stellar parametrization with cross-survey validity, high accuracy, and high precision. These are key to homogenize the output from future surveys, such as 4MOST or WEAVE.
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22. Atomic data
- ID:
- ivo://CDS.VizieR/J/A+AS/108/287
- Title:
- Atomic data
- Short Name:
- J/A+AS/108/287
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/A+A/525/A59
- Title:
- Atomic data for Al ions
- Short Name:
- J/A+A/525/A59
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radiative and Auger decay data have been calculated for modeling the K lines of the aluminium isonuclear sequence, from Al0 to Al11+. Level energies, transition wavelengths, radiative transition probabilities, and radiative and Auger widths have been determined using Cowan's Hartree-Fock with relativistic corrections (HFR) method. Results are compared with data sets computed with the AUTOSTRUCTURE and GRASP atomic structure codes and with available experimental and theoretical values, mainly in highly ionized ions and in the solid state.
- ID:
- ivo://CDS.VizieR/J/A+A/565/A77
- Title:
- Atomic data for FeIX
- Short Name:
- J/A+A/565/A77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a new large-scale intermediate-coupling frame transformation R-matrix scattering calculation for electron collisional excitation of Fe IX. The target includes all the main configurations up to n=5, to improve our earlier R-matrix and distorted-wave (DW) calculations for the n=3,4 levels. Unlike similar calculations which we carried out for the other coronal iron ions, in this case the larger target does not significantly affect the collision strengths of the strongest transitions to the n=3,4 levels. Some differences are however present for a few transitions, in particular for the 3d-4p line at 197.86{AA}. For the weaker transitions, significant enhancements due to extra resonances resulting from this much bigger target are found. Several new line identifications are suggested. We find excellent agreement between predicted and observed line intensities in the EUV (Hinode EIS) showing that Fe IX lines provide a reliable temperature diagnostic. We also show that the visible forbidden lines are a good diagnostic to measure electron densities.
- ID:
- ivo://CDS.VizieR/J/A+A/543/A44
- Title:
- Atomic data for iron peak and light odd-Z ions
- Short Name:
- J/A+A/543/A44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Complete data sets of level energies, transition wavelengths, A-values, radiative and Auger widths and fluorescence yields for K-vacancy levels of the F, Na, P, Cl, K, Sc, Ti, V, Cr, Mn, Co, Cu and Zn isonuclear sequences have been computed by a Hartree-Fock method that includes relativistic corrections as implemented in Cowan's atomic structure computer suite. The atomic parameters for more than 3 million fine- structure K lines have been determined. Ions with electron number N>9 are treated for the first time, and detailed comparisons with available measurements and theoretical data for ions with N=<9 are carried out in order to estimate reliable accuracy ratings.
- ID:
- ivo://CDS.VizieR/J/A+A/533/A62
- Title:
- Atomic Data for Neutron-Capture Elements. II
- Short Name:
- J/A+A/533/A62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multi-configuration Breit-Pauli distorted-wave photoionization (PI) cross sections and radiative recombination (RR) and dielectronic recombination (DR) rate coefficients for the first six krypton ions. These were calculated with the AUTOSTRUCTURE code, using semi-relativistic radial wavefunctions in intermediate coupling.
- ID:
- ivo://CDS.VizieR/J/A+AS/105/77
- Title:
- Atomic data for O VIII and Fe XVII
- Short Name:
- J/A+AS/105/77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The atomic data required to analyse low density coronal plasmas have been calculated and used to interpret X-ray spectra observed by the Flat Crystal Spectrometer of the SMM/NASA satellite in the 14-19 A wavelength range. The emission lines correspond mainly to Fe XVI, Fe XVII, Fe XVIII and some ones to O VII, O VIII.
- ID:
- ivo://CDS.VizieR/J/A+A/645/A106
- Title:
- Atomic data for the Gaia-ESO Survey
- Short Name:
- J/A+A/645/A106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the atomic data that were used for the abundance analyses of FGK-type stars carried out within the Gaia-ESO Public Spectroscopic Survey in the years 2012 to 2019. The Gaia-ESO survey is one among several current and future stellar spectroscopic surveys producing abundances for Milky-Way stars on an industrial scale. We present an unprecedented effort to create a homogeneous common line list, which was used by several abundance analysis groups using different radiative transfer codes to calculate synthetic spectra and equivalent widths. The atomic data are accompanied by quality indicators and detailed references to the sources. An overview of molecular data is also given. Among a subset of over 1300 lines of 35 elements in the wavelength ranges from 475nm to 685nm and from 850nm to 895nm we identified about 200 lines of 24 species which have accurate gf-values and are free of blends in the spectra of the Sun and Arcturus.
- ID:
- ivo://CDS.VizieR/J/A+A/624/A60
- Title:
- Atomic data for unblended lines in FGK stars
- Short Name:
- J/A+A/624/A60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Fundamental atomic transition parameters, such as oscillator strengths and rest wavelengths, play a key role in modelling and understanding the chemical composition of stars in the universe. Despite the significant work under way to produce these parameters for many astrophysically important ions, uncertainties in these parameters remain large and can limit the accuracy of chemical abundance determinations. The Belgian repository of fundamental atomic data and stellar spectra (BRASS) aims to provide a large systematic and homogeneous quality assessment of the atomic data available for quantitative spectroscopy. BRASS shall compare synthetic spectra against extremely high-quality observed spectra, at a resolution of ~85000 and signal-noise ratios of ~1000, for approximately 20 bright BAFGK spectral-type stars, in order to critically evaluate the atomic data available for over a thousand potentially useful spectral lines. A large-scale homogeneous selection of atomic lines is performed by synthesising theoretical spectra of literature atomic lines for FGK-type stars including the Sun, resulting in a selection of 1091 theoretically deep and unblended lines in the wavelength range 4200-6800{AA}, which may be suitable for quality assessment. Astrophysical log(gf) values are determined for the 1091 transitions using two commonly employed methods. The agreement of these log(gf) values are used to select well-behaved lines for quality assessment. We found 845 atomic lines to be suitable for quality assessment, of which 408 were found to be robust against systematic differences between analysis methods. Around 53% of the quality-assessed lines were found to have at least one literature log(gf) value in agreement with our derived values, though the remaining values can disagree by as much as 0.5dex. Only ~38% of FeI lines were found to have sufficiently accurate log(gf) values, increasing to ~70-75% for the remaining Fe-group lines.
- ID:
- ivo://CDS.VizieR/J/A+A/537/A22
- Title:
- Atomic data for X-ray lines of FeVIII and FeIX
- Short Name:
- J/A+A/537/A22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The distorted wave extension of the autostructure code has been used to calculate energy levels, radiative transition probabilities and collisional excitation rates of Fe VIII and Fe IX up to n=6 for Fe IX and n=7 for Fe VIII. We have compared some of the data with previous calculations, finding overall agreement for radiative transition rates, but interesting differences for some collisional data. ************************************************************************** * * * Sorry, but the author(s) never supplied the tabular material * * announced in the paper * * * **************************************************************************
