Special Issue "Atomic and Molecular Data Needs for Astronomy and Astrophysics"

A special issue of Galaxies (ISSN 2075-4434).

Deadline for manuscript submissions: closed (1 July 2018)

Special Issue Editors

Guest Editor
Dr. Maria Teresa Belmonte

Imperial College London, UK
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Interests: atomic data; plasma spectroscopy; transition probabilities; chemical abundances; laboratory astrophysics
Guest Editor
Dr. Carlos Allende-Prieto

Instituto de Astrofísica de Canarias, IAC, Spain
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Guest Editor
Dr. Ulrike Heiter

Uppsala University, Sweden
Website | E-Mail
Guest Editor
Prof. Alan Hibbert

Queen's University Belfast | QUB · Centre for Theoretical Atomic, Molecular and Optical Physics (CTAMOP)
Website | E-Mail
Guest Editor
Dr. Patrick de Laverny

Observatoire de la Côte d'Azur, France
Website | E-Mail

Special Issue Information

Dear Colleagues,

The analysis of astronomical spectra is vital for the determination of chemical abundances, the understanding of galactic formation and evolution and the synthesis of the different elements. However, despite the large investment of time and money spent in recording spectra of astrophysical objects at unprecedented resolution, the quantity and quality of the existing data lies far from the current needs of the astronomers and remains the Achilles' heel of galactic archaeology. This situation has resulted in an acute need for new measured and calculated atomic and molecular parameters of high-accuracy, high-resolution and completeness.

This Special Issue aims to encourage further dialogue and promote knowledge transfer between astronomers with strong atomic and molecular data needs and those who produce this data from laboratory measurements and calculations. We hope this will foster new collaborations for the future, which, through targeted measurements and calculations, will accelerate the rate at which astronomers' needs can be met. 

Contributions will focus on:

  • Data requirements of astronomers
  • Laboratory-measured atomic and molecular data
  • Theoretical calculations
  • Databases

The emphasis of this Special Issue will remain on knowledge transfer; with astronomers highlighting their data needs, and spectroscopists and theorists presenting new data of astronomical interest and the capabilities of their facilities for future collaborations. We encourage all astronomers involved in the ongoing spectroscopic surveys, such as Gaia-ESO, APOGEE or GALAH or in future ones, such as WEAVE, 4MOST or DESI, to contribute in order to explain their data needs. Review papers, as well as shorter contributions are very welcome.

Dr. Maria Teresa Belmonte
Dr. Carlos Allende-Prieto
Dr. Ulrike Heiter
Dr. Patrick de Laverny
Prof. Alan Hibbert
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Galaxies is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 350 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • atomic data
  • molecular data
  • stellar spectra
  • chemical abundances
  • oscillator strengths
  • atomic and molecular databases

Published Papers (12 papers)

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Research

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Open AccessArticle The Laboratory Astrophysics Spectroscopy Programme at Imperial College London
Galaxies 2018, 6(4), 109; https://doi.org/10.3390/galaxies6040109
Received: 2 August 2018 / Revised: 2 October 2018 / Accepted: 9 October 2018 / Published: 13 October 2018
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Abstract
Accurate atomic parameters, such as transition probabilities, wavelengths, and energy levels, are indispensable for the analysis of stellar spectra and the obtainment of chemical abundances. However, the quantity and quality of the existing data in many cases lie far from the current needs
[...] Read more.
Accurate atomic parameters, such as transition probabilities, wavelengths, and energy levels, are indispensable for the analysis of stellar spectra and the obtainment of chemical abundances. However, the quantity and quality of the existing data in many cases lie far from the current needs of astronomers, creating an acute need for laboratory measurements of matching accuracy and completeness to exploit the full potential of the very expensively acquired astrophysical spectra. The Fourier Transform Spectrometer at Imperial College London works in the vacuum ultraviolet-visible region with a resolution of 2,000,000 at 200 nm. We can acquire calibrated spectra of neutral, singly, and doubly ionized species. We collaborate with the National Institute of Standards and Technology (NIST) and the University of Lund to extend our measurements into the infrared region. The aim of this review is to explain the current capabilities of our experiment in an understandable way to bring the astronomy community closer to the field of laboratory astrophysics and encourage further dialogue between our laboratory and all those astronomers who need accurate atomic data. This exchange of ideas will help us to focus our efforts on the most urgently needed data. Full article
(This article belongs to the Special Issue Atomic and Molecular Data Needs for Astronomy and Astrophysics)
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Open AccessArticle The VAMDC Portal as a Major Enabler of Atomic and Molecular Data Citation
Galaxies 2018, 6(4), 105; https://doi.org/10.3390/galaxies6040105
Received: 25 June 2018 / Revised: 20 September 2018 / Accepted: 25 September 2018 / Published: 3 October 2018
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Abstract
VAMDC bridged the gap between atomic and molecular (A&M) producers and users through providing an interoperable e-infrastructure connecting A&M databases, as well as tools to extract and manipulate those data. The current paper highlights the usage of the VAMDC Portal, recalls how data
[...] Read more.
VAMDC bridged the gap between atomic and molecular (A&M) producers and users through providing an interoperable e-infrastructure connecting A&M databases, as well as tools to extract and manipulate those data. The current paper highlights the usage of the VAMDC Portal, recalls how data citation is implemented within VAMDC and provides insights about usage of VAMDC that will increase the impact factor of A&M producers and will offer a more reliable citation of A&M datasets included in application fields. Full article
(This article belongs to the Special Issue Atomic and Molecular Data Needs for Astronomy and Astrophysics)
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Open AccessArticle VALD: The Meeting Point of Data Producers and Data Users
Received: 25 June 2018 / Revised: 2 August 2018 / Accepted: 30 August 2018 / Published: 3 September 2018
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Abstract
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 of lines for fine spectral synthesis and for opacity calculations are collected in the present version of
[...] Read more.
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 of lines for fine spectral synthesis and for opacity calculations are collected in the present version of VALD (VALD3). Critical evaluation of the data and the diversity of extraction tools support the high popularity of VALD among users. The data model of VALD3 incorporates obligatory links to the bibliography making our database more attractive as a 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. Full article
(This article belongs to the Special Issue Atomic and Molecular Data Needs for Astronomy and Astrophysics)
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Open AccessArticle Towards the Provision of Accurate Atomic Data for Neutral Iron
Received: 30 June 2018 / Revised: 8 August 2018 / Accepted: 21 August 2018 / Published: 25 August 2018
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Abstract
The rich emission and absorption line spectra of Fe I may be used to extract crucial information on astrophysical plasmas, such as stellar metallicities. There is currently a lack, in quality and quantity, of accurate level-resolved effective electron-impact collision strengths and oscillator strengths
[...] Read more.
The rich emission and absorption line spectra of Fe I may be used to extract crucial information on astrophysical plasmas, such as stellar metallicities. There is currently a lack, in quality and quantity, of accurate level-resolved effective electron-impact collision strengths and oscillator strengths for radiative transitions. Here, we discuss the challenges in obtaining an accurate model of the neutral iron atom and compare our theoretical fine-structure energy levels with observation for several increasingly large models. Radiative data is presented for several transitions for which the atomic data is accurately known. Full article
(This article belongs to the Special Issue Atomic and Molecular Data Needs for Astronomy and Astrophysics)
Open AccessArticle Benchmarking Current Capabilities for the Generation of Excitation and Photoionisation Atomic Data
Received: 25 June 2018 / Revised: 23 July 2018 / Accepted: 20 August 2018 / Published: 21 August 2018
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Abstract
The spectra currently emerging from modern ground- and space-based astronomical instruments are of exceptionally high quality and resolution. To meaningfully analyse these spectra, researchers utilise complex modelling codes to replicate the observations. The main inputs to these codes are atomic data such as
[...] Read more.
The spectra currently emerging from modern ground- and space-based astronomical instruments are of exceptionally high quality and resolution. To meaningfully analyse these spectra, researchers utilise complex modelling codes to replicate the observations. The main inputs to these codes are atomic data such as excitation and photoionisation cross sections, as well as radiative transition probabilities, energy levels, and line strengths. In this publication, the current capabilities of the numerical methods and computer packages used in the generation of these data are discussed. Particular emphasis is given to Fe-peak species and the heavy systems of tungsten and molybdenum. Some of the results presented to highlight certain issues and/or advances have already been published in the literature, while other sections present new recently evaluated atomic data for the first time. Full article
(This article belongs to the Special Issue Atomic and Molecular Data Needs for Astronomy and Astrophysics)
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Open AccessArticle R-Matrix Scattering Calculations for Iron-Peak Species: Photoionisation of Fe I and Electron-Impact Excitation of Fe II
Received: 18 June 2018 / Revised: 6 August 2018 / Accepted: 8 August 2018 / Published: 10 August 2018
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Abstract
An abundance of absorption and emission lines of iron-peak species such as Fe I and Fe II can be seen in the spectra of many astrophysical objects. Thus, the accurate modelling of such spectra requires sets of high quality atomic data for these
[...] Read more.
An abundance of absorption and emission lines of iron-peak species such as Fe I and Fe II can be seen in the spectra of many astrophysical objects. Thus, the accurate modelling of such spectra requires sets of high quality atomic data for these species. In this paper, we present preliminary results from the present electron-impact excitation calculations for Fe II and fine-structure resolved photoionisation calculations for Fe I employing the Dirac atomic R-matrix and Breit–Pauli R-matrix methods. For the Fe II excitation, we compare results with all existing calculations, and for the Fe I photoionisation, we present a sample of level-resolved cross-sections. The calculations and results described throughout will be of use to those requiring high quality atomic data for modelling a wide variety of astrophysical objects. Full article
(This article belongs to the Special Issue Atomic and Molecular Data Needs for Astronomy and Astrophysics)
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Open AccessArticle The Belgian Repository of Fundamental Atomic Data and Stellar Spectra (BRASS) Identifying Fruitful Methods for Producing Atomic Data
Received: 1 July 2018 / Revised: 17 July 2018 / Accepted: 23 July 2018 / Published: 25 July 2018
Cited by 1 | PDF Full-text (255 KB) | HTML Full-text | XML Full-text
Abstract
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
[...] Read more.
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. Full article
(This article belongs to the Special Issue Atomic and Molecular Data Needs for Astronomy and Astrophysics)
Open AccessArticle Successes and Difficulties in Calculating Atomic Oscillator Strengths and Transition Rates
Received: 20 June 2018 / Revised: 17 July 2018 / Accepted: 18 July 2018 / Published: 24 July 2018
Cited by 1 | PDF Full-text (275 KB) | HTML Full-text | XML Full-text
Abstract
There is an on-going need for accurate oscillator strengths to be used in astrophysical applications, particularly in plasma diagnostics and in the modelling of stellar atmospheres and the interstellar medium. There are several databases in regular use which contain some of the required
[...] Read more.
There is an on-going need for accurate oscillator strengths to be used in astrophysical applications, particularly in plasma diagnostics and in the modelling of stellar atmospheres and the interstellar medium. There are several databases in regular use which contain some of the required data, although often insufficiently complete, and sometimes not sufficiently accurate. In addition, several atomic structure packages are available through the literature, or from their individual authors, which would allow further calculations to be undertaken. Laboratory measurements provide an important check on the accuracy of calculated data, and the combined efforts of theorists and experimentalists have succeeded in providing data of an accuracy sufficient for some astrophysical applications. However, the insufficiency or inadequacy of atomic data is a continuing problem. We discuss in the context of appropriate examples some of the principal steps which researchers have taken to calculate accurate oscillator strengths, including both ab initio results and also various extrapolation processes which attempt to improve such results. We also present some examples of the main causes of difficulty in such calculations, particularly for complex (many-electron) ions, and indicate ways in which the difficulties might be overcome. Full article
(This article belongs to the Special Issue Atomic and Molecular Data Needs for Astronomy and Astrophysics)
Open AccessArticle Estimating the Level of Uncertainty in Electron-Impact Excitation and Photoionisation Rates of Low-Ionised Stages of Ni Ions
Received: 26 June 2018 / Revised: 6 July 2018 / Accepted: 12 July 2018 / Published: 18 July 2018
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Abstract
Ni iv lines can be used as diagnostics for temperature and density for various astrophysical objects. In addition, ionization of Ni2+ is one of the causes of the opacity in the interstellar medium. We calculate the photoionization of Ni2+
[...] Read more.
Ni iv lines can be used as diagnostics for temperature and density for various astrophysical objects. In addition, ionization of Ni2+ is one of the causes of the opacity in the interstellar medium. We calculate the photoionization of Ni2+ and the electron-impact excitation of Ni3+. We use a fully-relativistic Dirac Atomic R-Matrix Code (DARC) method. We include a large set of configurations in the expansion of the wave functions of the target, up to the n=6 atomic shell. We show preliminary results for the photoionization cross-sections of Ni2+ and the electron-impact excitation collision strengths of Ni3+. The expected final results can be implemented in the available software packages for astrophysical plasma simulation, such as CLOUDY. We also show a preliminary estimation of the error of the data by the comparison of different sets of calculations. Full article
(This article belongs to the Special Issue Atomic and Molecular Data Needs for Astronomy and Astrophysics)
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Open AccessArticle The Collisional Atomic Processes of Rydberg Hydrogen and Helium Atoms: Astrophysical Relevance
Received: 17 June 2018 / Revised: 6 July 2018 / Accepted: 12 July 2018 / Published: 16 July 2018
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Abstract
Elementary processes in astrophysical environments traditionally attract researchers’ attention. We present the data needed for the inclusion of the specific atomic collisional processes in the investigation of the optical and kinetic properties of weakly ionized stellar atmosphere layers. The first type of processes
[...] Read more.
Elementary processes in astrophysical environments traditionally attract researchers’ attention. We present the data needed for the inclusion of the specific atomic collisional processes in the investigation of the optical and kinetic properties of weakly ionized stellar atmosphere layers. The first type of processes are collisional ionisation (chemi-ionization) processes, and the second ones are excitation and de-excitation (i.e., ( n - n )-mixing processes). We give the rate coefficients of the aforementioned processes for the conditions that exist in the solar photosphere, the atmosphere of DB white dwarfs, M-type red dwarfs, etc. Full article
(This article belongs to the Special Issue Atomic and Molecular Data Needs for Astronomy and Astrophysics)
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Open AccessArticle Recent Development of the Atomic Line List
Received: 7 May 2018 / Revised: 1 June 2018 / Accepted: 2 June 2018 / Published: 8 June 2018
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Abstract
The Atomic Line List is an online database of wavelengths and transition probabilities of atomic lines. It is primarily set up as a tool to help identify unknown spectral features. This paper briefly describes the web interface, how the line list is constructed,
[...] Read more.
The Atomic Line List is an online database of wavelengths and transition probabilities of atomic lines. It is primarily set up as a tool to help identify unknown spectral features. This paper briefly describes the web interface, how the line list is constructed, and what development is currently being undertaken for the next release. Full article
(This article belongs to the Special Issue Atomic and Molecular Data Needs for Astronomy and Astrophysics)

Review

Jump to: Research

Open AccessReview Molecular Data Needs for Modelling AGB Stellar Winds and Other Molecular Environments
Received: 29 June 2018 / Revised: 1 August 2018 / Accepted: 2 August 2018 / Published: 7 August 2018
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Abstract
The modern era of highly sensitive telescopes is enabling the detection of more and more molecular species in various astronomical environments. Many of these are now being carefully examined for the first time. However, to move beyond detection to more detailed analysis such
[...] Read more.
The modern era of highly sensitive telescopes is enabling the detection of more and more molecular species in various astronomical environments. Many of these are now being carefully examined for the first time. However, to move beyond detection to more detailed analysis such as radiative transfer modelling, certain molecular properties need to be properly measured and calculated. The importance of contributions from vibrationally excited states or collisional (de-)excitations can vary greatly, depending on the specific molecule and the environment being studied. Here, we discuss the present molecular data needs for detailed radiative transfer modelling of observations of molecular rotational transitions, primarily in the (sub-)millimetre and adjacent regimes, and with a focus on the stellar winds of AGB stars. Full article
(This article belongs to the Special Issue Atomic and Molecular Data Needs for Astronomy and Astrophysics)
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