scholarly journals VALD: The Meeting Point of Data Producers and Data Users

2018 ◽  
Author(s):  
Tatiana Ryabchikova ◽  
Yury Pakhomov ◽  
Nikolai Piskunov
Keyword(s):  
Data Model ◽  
Spectral Synthesis ◽  
Energy Levels ◽  
Critical Evaluation ◽  
Spectral Lines ◽  
Atomic Data ◽  
Spectra Analysis ◽  
Stellar Spectra ◽  
Data Content ◽  
Hyperfine Structures

Vienna Atomic Line Database (VALD) contains data on atomic and molecular energy levels and parameters of spectral lines required for stellar spectra analysis. Hundreds of millions lines for fine spectral synthesis and for opacity calculations are collected in present version of VALD (VALD3). Critical evaluation of the data and the diversity of extraction tools support high popularity of VALD among users. The data model of VALD3 incorporates obligatory links to the bibliography making our database more attractive as publishing platform for data producers. The VALD data quality and completeness are constantly improving allowing better reproduction of stellar spectra. To illustrate continuous evolution of the data content we present a comparative analysis of the recent experimental and theoretical atomic data for Fe-group elements, which will be included in the next VALD release. This release will also include a possibility for extracting the line data with full isotopic and hyperfine structures.

Systematic calculations of energy levels and transitions rates in Mo XXVIII

2020 ◽  
Vol 75 (8) ◽  
pp. 739-747
Author(s):  
Feng Hu ◽  
Yan Sun ◽  
Maofei Mei
Keyword(s):  
Energy Levels ◽  
Oscillator Strengths ◽  
Atomic Data ◽  
Data Sets ◽  
Electron Systems ◽  
Excitation Energies ◽  
Experimental Values ◽  
Qed Effects ◽  
Hyperfine Structures ◽  
Good Agreement

AbstractComplete and consistent atomic data, including excitation energies, lifetimes, wavelengths, hyperfine structures, Landé gJ-factors and E1, E2, M1, and M2 line strengths, oscillator strengths, transitions rates are reported for the low-lying 41 levels of Mo XXVIII, belonging to the n = 3 states (1s22s22p6)3s23p3, 3s3p4, and 3s23p23d. High-accuracy calculations have been performed as benchmarks in the request for accurate treatments of relativity, electron correlation, and quantum electrodynamic (QED) effects in multi-valence-electron systems. Comparisons are made between the present two data sets, as well as with the experimental results and the experimentally compiled energy values of the National Institute for Standards and Technology wherever available. The calculated values including core-valence correction are found to be in a good agreement with other theoretical and experimental values. The present results are accurate enough for identification and deblending of emission lines involving the n = 3 levels, and are also useful for modeling and diagnosing plasmas.

scholarly journals Laboratory astrophysics for the interpretation of stellar spectra

2019 ◽  
Vol 15 (S350) ◽  
pp. 345-349
Author(s):  
Ulrike Heiter
Keyword(s):  
Milky Way ◽  
Chemical Elements ◽  
Spectral Lines ◽  
Laboratory Astrophysics ◽  
Atomic Data ◽  
Milky Way Galaxy ◽  
Infrared Wavelength ◽  
Stellar Spectra ◽  
Continuous Activities ◽  
Host Stars

AbstractHigh-resolution stellar spectra are important tools for studying the chemical evolution of the Milky Way Galaxy, tracing the origin of chemical elements, and characterizing planetary host stars. Large amounts of data have been accumulating, in particular in the optical and infrared wavelength regions. The observed spectral lines are interpreted using model spectra that are calculated based on transition data for numerous species, in particular neutral and singly ionized atoms. We rely heavily on the continuous activities of laboratory astrophysics groups that produce high-quality experimental and theoretical atomic data for the relevant transitions. We give examples for the precision with which the chemical composition of stars observed by different surveys can be determined, and discuss future needs from laboratory astrophysics.

Atomic structure calculations and study of EUV and SXR spectral lines in Cu-like ions

2016 ◽  
Vol 94 (9) ◽  
pp. 839-852
Author(s):  
Arun Goyal ◽  
Indu Khatri ◽  
Narendra Singh ◽  
A.K. Singh ◽  
Rinku Sharma ◽  
...  
Keyword(s):  
Quantum Electrodynamics ◽  
Cell Biology ◽  
Extreme Ultraviolet ◽  
Energy Levels ◽  
Electron Excitation ◽  
Spectral Lines ◽  
Atomic Data ◽  
Atomic Structure Calculations ◽  
Structure Calculations ◽  
Good Agreement

In the present work, we provide a most extensive and detailed study of highly ionized Cu-like ions and diagnose extreme ultraviolet (EUV) and soft X-ray (SXR) transitions with N-shell electron excitation to M-shell and higher shells. We have determined energy levels and lifetimes for lowest 27 fine-structure levels by adopting multiconfiguration Dirac–Fock (MCDF) with the inclusion of quantum electrodynamics (QED) as well as Breit corrections as a first-order perturbation theory. We have also reported complete radiative data for strong electric dipole transitions within lowest 27 levels. We have compared our calculated results with theoretically calculated and experimentally measured results available in the literature, to measure the credibility and genuineness of our results, and achieve good agreement. Further, because of insufficiency of adequate and complete atomic data for higher levels of highly ionized Cu-like ions in the literature, we have performed other equivalent parallel calculations by implementing fully relativistic distorted wave flexible atomic code (FAC) to ensure the accuracy of our results. Additionally, we have also presented transition wavelengths of Nα transitions of high-Z Cu-like ions by using Moseley’s law. We believe that the large amount of atomic data presented in this paper may be useful in fusion and astrophysical plasma and in several applications, especially in lithography and cell biology.

scholarly journals The Belgian repository of fundamental atomic data and stellar spectra (BRASS)

2019 ◽  
Vol 624 ◽  
pp. A60 ◽  
Author(s):  
M. Laverick ◽  
A. Lobel ◽  
P. Royer ◽  
T. Merle ◽  
C. Martayan ◽  
...  
Keyword(s):  
Quality Assessment ◽  
Large Scale ◽  
Spectral Lines ◽  
Oscillator Strengths ◽  
Atomic Data ◽  
Chemical Abundance ◽  
Stellar Spectra ◽  
Atomic Lines ◽  
The Universe ◽  
Selection Of

Context. 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.Aims. 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 ∼85 000 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.Methods. 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 Å, which may be suitable for quality assessment. Astrophysical log(g f) values are determined for the 1091 transitions using two commonly employed methods. The agreement of these log(g f) values are used to select well-behaved lines for quality assessment.Results. 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(g f) value in agreement with our derived values, though the remaining values can disagree by as much as 0.5 dex. Only ∼38% of Fe Ilines were found to have sufficiently accurate log(g f) values, increasing to ∼70–75% for the remaining Fe-group lines.

scholarly journals The Belgian Repository of Fundamental Atomic Data and Stellar Spectra (BRASS) Identifying Fruitful Methods for Producing Atomic Data

Galaxies ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 78 ◽  
Author(s):  
Mike Laverick ◽  
Alex Lobel ◽  
Pierre Royer ◽  
Christophe Martayan ◽  
Thibault Merle ◽  
...  
Keyword(s):  
Quality Assessment ◽  
Atomic Physics ◽  
Spectral Synthesis ◽  
Atomic Data ◽  
High Quality ◽  
Stellar Spectra ◽  
Physics Community

The Belgian repository of fundamental atomic data and stellar spectra (BRASS) aims to provide the largest systematic and homogeneous quality assessment to-date of input atomic data required for stellar spectral synthesis. In addition to quality-assessed atomic data, BRASS shall also provide of a range of extremely high-quality benchmark stellar spectra spanning late B-type stars to early K-type stars. In this paper, we summarise the project’s progress and available results to-date. We provide a brief comparison between our results and the BRASS project’s compiled and cross-matched atomic literature, with the goal of providing useful feedback to the atomic community on which methods may produce more reliable and accurate atomic data. We hope that the examples presented here stimulate further investigation by the atomic physics community.

BRASS: Cross-match of atomic repositories and spectral line blending investigations

2017 ◽  
Vol 95 (9) ◽  
pp. 843-846 ◽  
Author(s):  
M. Laverick ◽  
A. Lobel ◽  
P. Royer ◽  
C. Martayan ◽  
T. Merle
Keyword(s):  
Spectral Line ◽  
State Of The Art ◽  
Spectral Synthesis ◽  
Atomic Data ◽  
High Quality ◽  
Stellar Spectra ◽  
Synthetic Spectra ◽  
Atomic Lines ◽  
Quality Assessments ◽  
Cross Match

The Belgian repository of fundamental atomic data and stellar spectra (BRASS) aims to critically evaluate atomic data, from publicly available repositories, by comparing state-of-the-art synthetic spectra against high-quality benchmark stellar spectra. In preparation for our assessment we have cross-matched atomic line transitions from several different databases. Our investigation revealed significant updates in log(gf) values, sometimes as large as 2–4 dex, that fully justify the need for systematic quality assessments of the atomic data. We have also investigated the spectral line blending of an initial subset of 2647 atomic lines using spectral synthesis calculations, for the spectral types BAFGK.

Spectroscopic study of EUV and SXR transitions of Cs XXV

2018 ◽  
Vol 96 (8) ◽  
pp. 871-877
Author(s):  
Arun Goyal ◽  
Indu Khatri ◽  
Narendra Singh ◽  
Sunny Aggarwal ◽  
A.K. Singh ◽  
...  
Keyword(s):  
Theoretical Study ◽  
Extreme Ultraviolet ◽  
Energy Levels ◽  
Spectral Lines ◽  
Atomic Data ◽  
Distorted Wave ◽  
Fusion Plasma ◽  
Excitation Energies ◽  
X Ray ◽  
Plasma Research

We report an extensive and elaborate theoretical study of atomic data for Cs XXV by using multi-configuration Dirac–Fock method and calculated energy levels for the lowest 110 fine structure levels. We have presented the radiative data for electric and magnetic dipole (E1, M1) and quadrupole (E2, M2) transitions among lowest 110 levels. We have made comparisons of our calculated excitation energies with theoretically calculated and experimentally observed energy levels. We have studied the effect of correlation by introducing more configurations in our calculations. We have also computed energy levels by performing similar relativistic distorted wave calculations using Flexible Atomic Code. Additionally, we have also provided new atomic data for Cs XXV and identified extreme ultraviolet and soft X-ray spectral lines with gA spectra for E1 and M2 transitions, which are not published elsewhere in the literature. We believe that our results may be beneficial in fusion plasma research and applications.

scholarly journals The Belgian repository of fundamental atomic data and stellar spectra (BRASS)

2018 ◽  
Vol 612 ◽  
pp. A60 ◽  
Author(s):  
M. Laverick ◽  
A. Lobel ◽  
T. Merle ◽  
P. Royer ◽  
C. Martayan ◽  
...  
Keyword(s):  
Spectral Lines ◽  
Oscillator Strengths ◽  
Atomic Line ◽  
Atomic Data ◽  
Stellar Spectra ◽  
Line List ◽  
The Impact ◽  
Cross Match ◽  
Atomic Parameters ◽  
Non Parametric

Context. Fundamental atomic parameters, such as oscillator strengths, play a key role in modelling and understanding the chemical composition of stars in the Universe. Despite the significant work underway to produce these parameters for many astrophysically important ions, uncertainties in these parameters remain large and can propagate throughout the entire field of astronomy. Aims. The Belgian repository of fundamental atomic data and stellar spectra (BRASS) aims to provide the largest systematic and homogeneous quality assessment of atomic data to date in terms of wavelength, atomic and stellar parameter coverage. To prepare for it, we first compiled multiple literature occurrences of many individual atomic transitions, from several atomic databases of astrophysical interest, and assessed their agreement. In a second step synthetic spectra will be compared against extremely high-quality observed spectra, for a large number of BAFGK spectral type stars, in order to critically evaluate the atomic data of a large number of important stellar lines. Methods. Several atomic repositories were searched and their data retrieved and formatted in a consistent manner. Data entries from all repositories were cross-matched against our initial BRASS atomic line list to find multiple occurrences of the same transition. Where possible we used a new non-parametric cross-match depending only on electronic configurations and total angular momentum values. We also checked for duplicate entries of the same physical transition, within each retrieved repository, using the non-parametric cross-match. Results. We report on the number of cross-matched transitions for each repository and compare their fundamental atomic parameters. We find differences in log(gf) values of up to 2 dex or more. We also find and report that ~2% of our line list and Vienna atomic line database retrievals are composed of duplicate transitions. Finally we provide a number of examples of atomic spectral lines with different retrieved literature log(gf) values, and discuss the impact of these uncertain log(gf) values on quantitative spectroscopy.

scholarly journals The Prime Beat Components Extraction Method for the Time Spectra Analysis of Nuclear Resonant Forward Scattering

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1657
Author(s):  
Tang Li ◽  
Xiaowei Zhang
Keyword(s):  
Hyperfine Structure ◽  
Fourier Transformation ◽  
Extraction Method ◽  
Energy Levels ◽  
Forward Scattering ◽  
Spectral Lines ◽  
Quantum Beats ◽  
Temperature Dependent ◽  
Spectra Analysis ◽  
Nuclear Resonant Forward Scattering

Spectra of quantum beats (QBs) of nuclear resonant forward scattering contain the interference information of all allowed energy transitions of a nucleus, which makes it complicated to extract hyperfine structure directly. Here, we propose a new method, based upon the extraction of prime beat components, to understand QBs. In this method, the origin of major spectral lines in the Fourier Transformation of QBs is studied, and the energy levels of hyperfine structure are obtained directly from the QBs. We applied this method to the temperature dependent QBs of hematite. The Morin temperature and hyperfine structure obtained by this method are in consistent with that by conventional Mössbauer spectroscopy (MS). It serves to interpret the components of QBs of nuclear resonant forward scattering as simple as the conventional (MS).

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