Special Issue "Spectral Line Shapes in Astrophysics and Related Topics"

A special issue of Atoms (ISSN 2218-2004).

Deadline for manuscript submissions: closed (1 September 2017)

Special Issue Editors

Guest Editor
Dr. Milan S. Dimitrijević

Astronomical Observatory, Belgrade, Serbia
Website | E-Mail
Interests: stark broadening; line profiles; stellar spectra; atomic and ionic collisions with formation of quasimolecules; atomic processes in white dwarfs and solar type stars; astroinformatics; databases; history and philosophy of science
Guest Editor
Prof. Dr. Luka Č. Popović

Astronomical Observatory, Belgrade, Serbia
Website | E-Mail
Interests: astrophysical spectra; spectra of active galactic nuclei; line profiles; stark broadening; astroinformatics; databases

Special Issue Information

Dear Colleagues,

Spectral lines, their widths, and shapes, are powerful tools for emitting/absorbing gas diagnostics in different astrophysical objects (from the Solar system to the most distant objects in the Universe—quasars). The emission/absorption lines of astrophysical objects are produced over a wide range of distances from an observer and under a wide range of physical and kinematical conditions. Therefore, in astrophysical objects, the lines from X-ray (Fe K) to the radio (radio recombination line) have been observed. On the other hand, the experimental and theoretical investigations of laboratory plasma have been applied in spectroscopic astrophysical research, especially in atomic data needed for line shape calculations. Data on spectral lines and their profiles are also important for diagnostics, analysis and modelling of fusion plasma, laser produced plasma, lasers design and development and various plasmas in industry and technology like light sources based on plasmas or welding and piercing of metals by laser produced plasma. This Special Issue of Atoms will highlight the need for continuing research on the spectral line shapes and will review present investigation in astrophysics where spectral line shapes have been used as a tool to investigate physical and kinematical properties of celestial objects. Moreover, there will be a number of studies of spectral line shapes in laboratory plasma, fusion plasma, laser-produced plasma, and about atomic data needed for the calculation of spectral line properties. 

Dr. Milan S. Dimitrijević
Prof. Luka Č. Popović
Guest Editors

Manuscript Submission Information

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Keywords

  •  spectra
  • line profiles
  • stellar spectra
  • AGN spectra
  • interstellar spectra
  • laboratory plasma
  • fusion plasma
  • lasers
  • plasma in industry
  • stars
  • extragalactic objects

Published Papers (9 papers)

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Research

Open AccessFeature PaperArticle Stark-Zeeman Line Shape Modeling for Magnetic White Dwarf and Tokamak Edge Plasmas: Common Challenges
Atoms 2017, 5(4), 36; doi:10.3390/atoms5040036
Received: 23 August 2017 / Revised: 21 September 2017 / Accepted: 29 September 2017 / Published: 4 October 2017
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Abstract
The shape of atomic spectral lines in plasmas contains information on the plasma parameters, and can be used as a diagnostic tool. Under specific conditions, the plasma located at the edge of tokamaks has parameters similar to those in magnetic white dwarf stellar
[...] Read more.
The shape of atomic spectral lines in plasmas contains information on the plasma parameters, and can be used as a diagnostic tool. Under specific conditions, the plasma located at the edge of tokamaks has parameters similar to those in magnetic white dwarf stellar atmospheres, which suggests that the same line shape models can be used. A problem common to tokamak and magnetic white dwarfs concerns the modeling of Stark broadening of hydrogen lines in the presence of an external magnetic field and the related Zeeman effect. In this work, we focus on a selection of issues relevant to Stark broadening in magnetized hydrogen plasmas. Various line shape models are presented and discussed through applications to ideal cases. Full article
(This article belongs to the Special Issue Spectral Line Shapes in Astrophysics and Related Topics)
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Open AccessFeature PaperArticle Line Shape Modeling for the Diagnostic of the Electron Density in a Corona Discharge
Atoms 2017, 5(4), 35; doi:10.3390/atoms5040035
Received: 31 August 2017 / Revised: 23 September 2017 / Accepted: 24 September 2017 / Published: 28 September 2017
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Abstract
We present an analysis of spectra observed in a corona discharge designed for the study of dielectrics in electrical engineering. The medium is a gas of helium and the discharge was performed at the vicinity of a tip electrode under high voltage. The
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We present an analysis of spectra observed in a corona discharge designed for the study of dielectrics in electrical engineering. The medium is a gas of helium and the discharge was performed at the vicinity of a tip electrode under high voltage. The shape of helium lines is dominated by the Stark broadening due to the plasma microfield. Using a computer simulation method, we examine the sensitivity of the He 492 nm line shape to the electron density. Our results indicate the possibility of a density diagnostic based on passive spectroscopy. The influence of collisional broadening due to interactions between the emitters and neutrals is discussed. Full article
(This article belongs to the Special Issue Spectral Line Shapes in Astrophysics and Related Topics)
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Open AccessFeature PaperArticle Effect of Turbulence on Line Shapes in Astrophysical and Fusion Plasmas
Atoms 2017, 5(4), 34; doi:10.3390/atoms5040034
Received: 30 August 2017 / Revised: 15 September 2017 / Accepted: 18 September 2017 / Published: 25 September 2017
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Abstract
We look at the effect of wave collapse turbulence on a hydrogen line shape in plasma. An atom immersed in plasma affected by strong Langmuir turbulence may be perturbed by a sequence of wave packets with a maximum electric field magnitude that is
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We look at the effect of wave collapse turbulence on a hydrogen line shape in plasma. An atom immersed in plasma affected by strong Langmuir turbulence may be perturbed by a sequence of wave packets with a maximum electric field magnitude that is larger than the Holtsmark field. For such conditions, we propose to calculate the shape of the hydrogen Lyman α Lyman β and Balmer α lines with a numerical integration of the Schrödinger equation coupled to a simulation of a sequence of electric fields modeling the effects of the Langmuir wave. We present and discuss several line profiles of Lyman and Balmer lines. Full article
(This article belongs to the Special Issue Spectral Line Shapes in Astrophysics and Related Topics)
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Open AccessFeature PaperArticle Stark Broadening from Impact Theory to Simulations
Atoms 2017, 5(3), 32; doi:10.3390/atoms5030032
Received: 31 August 2017 / Accepted: 11 September 2017 / Published: 20 September 2017
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Abstract
Impact approximation is widely used for calculating Stark broadening in a plasma. We review its main features and different types of models that make use of it. We discuss recent developments, in particular a quantum approach used for both the emitter and the
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Impact approximation is widely used for calculating Stark broadening in a plasma. We review its main features and different types of models that make use of it. We discuss recent developments, in particular a quantum approach used for both the emitter and the perturbers. Numerical simulations are a useful tool for gaining insight into the mechanisms at play in impact-broadening conditions. Our simple model allows the integration of the Schrödinger equation for an emitter submitted to a fluctuating electric field. We show how we can approach the impact results, and how we can investigate conditions beyond the impact approximation. The simple concepts developed in impact and simulation approaches enable the analysis of complex problems such as the effect of plasma rogue waves on hydrogen spectra. Full article
(This article belongs to the Special Issue Spectral Line Shapes in Astrophysics and Related Topics)
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Open AccessFeature PaperArticle Quasar Black Hole Mass Estimates from High-Ionization Lines: Breaking a Taboo?
Atoms 2017, 5(3), 33; doi:10.3390/atoms5030033
Received: 31 August 2017 / Revised: 12 September 2017 / Accepted: 14 September 2017 / Published: 20 September 2017
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Abstract
Can high ionization lines such as CIVλ1549 provide useful virial broadening estimators for computing the mass of the supermassive black holes that power the quasar phenomenon? The question has been dismissed by several workers as a rhetorical one because blue-shifted, non-virial
[...] Read more.
Can high ionization lines such as CIV λ 1549 provide useful virial broadening estimators for computing the mass of the supermassive black holes that power the quasar phenomenon? The question has been dismissed by several workers as a rhetorical one because blue-shifted, non-virial emission associated with gas outflows is often prominent in CIV λ 1549 line profiles. In this contribution, we first summarize the evidence suggesting that the FWHM of low-ionization lines like H β and MgII λ 2800 provide reliable virial broadening estimators over a broad range of luminosity. We confirm that the line widths of CIV λ 1549 is not immediately offering a virial broadening estimator equivalent to the width of low-ionization lines. However, capitalizing on the results of Coatman et al. (2016) and Sulentic et al. (2017), we suggest a correction to FWHM CIV λ 1549 for Eddington ratio and luminosity effects that, however, remains cumbersome to apply in practice. Intermediate ionization lines (IP ∼ 20–30 eV; AlIII λ 1860 and SiIII] λ 1892) may provide a better virial broadening estimator for high redshift quasars, but larger samples are needed to assess their reliability. Ultimately, they may be associated with the broad-line region radius estimated from the photoionization method introduced by Negrete et al. (2013) to obtain black hole mass estimates independent from scaling laws. Full article
(This article belongs to the Special Issue Spectral Line Shapes in Astrophysics and Related Topics)
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Open AccessFeature PaperArticle Radiative and Collisional Molecular Data and Virtual Laboratory Astrophysics
Atoms 2017, 5(3), 31; doi:10.3390/atoms5030031
Received: 4 September 2017 / Revised: 12 September 2017 / Accepted: 13 September 2017 / Published: 19 September 2017
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Abstract
Spectroscopy has been crucial for our understanding of physical and chemical phenomena. The interpretation of interstellar line spectra with radiative transfer calculations usually requires two kinds of molecular input data: spectroscopic data (such as energy levels, statistical weights, transition probabilities, etc.) and collision
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Spectroscopy has been crucial for our understanding of physical and chemical phenomena. The interpretation of interstellar line spectra with radiative transfer calculations usually requires two kinds of molecular input data: spectroscopic data (such as energy levels, statistical weights, transition probabilities, etc.) and collision data. This contribution describes how such data are collected, stored, and which limitations exist. Also, here we summarize challenges of atomic/molecular databases and point out our experiences, problems, etc., which we are faced with. We present overview of future developments and needs in the areas of radiative transfer and molecular data. Full article
(This article belongs to the Special Issue Spectral Line Shapes in Astrophysics and Related Topics)
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Open AccessFeature PaperArticle Stark Widths of Na IV Spectral Lines
Atoms 2017, 5(3), 29; doi:10.3390/atoms5030029
Received: 16 August 2017 / Revised: 8 September 2017 / Accepted: 14 September 2017 / Published: 18 September 2017
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Abstract
Sodium is a very important element for the research and analysis of astrophysical, laboratory, and technological plasmas, but neither theoretical nor experimental data on Stark broadening of Na IV spectral lines are present in the literature. Using the modified semiempirical method of Dimitrijević
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Sodium is a very important element for the research and analysis of astrophysical, laboratory, and technological plasmas, but neither theoretical nor experimental data on Stark broadening of Na IV spectral lines are present in the literature. Using the modified semiempirical method of Dimitrijević and Konjević, here Stark widths have been calculated for nine Na IV transitions. Na IV belongs to the oxygen isoelectronic sequence, and we have calculated Stark widths belonging to singlets, triplets, and quintuplets, as well as with different parent terms. This is used to discuss similarities within one transition array with different multiplicities and parent terms. Additionally, calculated widths will be implemented in the STARK-B database (http://stark-b.obspm.fr) which is also a part of the Virtual Atomic and Molecular Data Center (VAMDC—http://www.vamdc.org/). Full article
(This article belongs to the Special Issue Spectral Line Shapes in Astrophysics and Related Topics)
Open AccessFeature PaperArticle Semiclassical Stark Broadening Parameters of Ar VII Spectral Lines
Atoms 2017, 5(3), 27; doi:10.3390/atoms5030027
Received: 16 August 2017 / Revised: 1 September 2017 / Accepted: 6 September 2017 / Published: 8 September 2017
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Abstract
Using the semi-classical perturbation approach in the impact approximation, full width at half maximum and shift have been determined for eight spectral lines of Ar VII, for broadening by electron-, proton-, and He III-impacts. The results are provided for temperatures from 20,000 K
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Using the semi-classical perturbation approach in the impact approximation, full width at half maximum and shift have been determined for eight spectral lines of Ar VII, for broadening by electron-, proton-, and He III-impacts. The results are provided for temperatures from 20,000 K to 500,000 K, and for an electron density of 10 18 cm 3 . The obtained results will be included in the STARK-B database, which is also in the virtual atomic and molecular data center (VAMDC). Full article
(This article belongs to the Special Issue Spectral Line Shapes in Astrophysics and Related Topics)
Open AccessFeature PaperArticle Stark Widths of Ar II Spectral Lines in the Atmospheres of Subdwarf B Stars
Atoms 2017, 5(3), 26; doi:10.3390/atoms5030026
Received: 29 August 2017 / Accepted: 4 September 2017 / Published: 7 September 2017
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Abstract
Stark broadening parameters are of interest for many problems in astrophysics and laboratory plasmas investigation. Ar II spectral lines are observed in many kinds of stellar atmospheres such as the atmospheres of B-Type stars and subdwarf B stars. In this work, we present
[...] Read more.
Stark broadening parameters are of interest for many problems in astrophysics and laboratory plasmas investigation. Ar II spectral lines are observed in many kinds of stellar atmospheres such as the atmospheres of B-Type stars and subdwarf B stars. In this work, we present theoretical Stark widths for Ar II spectral lines. We use the impact semiclassical perturbation approach. Our results are compared with the available experimental values. Finally, the importance of the Stark broadening mechanism is studied in atmospheric conditions of subdwarf B stars. Full article
(This article belongs to the Special Issue Spectral Line Shapes in Astrophysics and Related Topics)
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