STARK-B Database Research Articles

Calculated Stark widths of the triply charged argon ion Ar iv

ABSTRACT In this work we studied the Stark widths of Ar iv ion which are important for modelling atmosphere of some particular stars. Using semiclassical perturbation and modified semi-empirical approach, we present in this work Stark widths of triply ionized argon Ar iv spectral lines which will be implemented in the STARK-B data base. Energy levels and oscillator strengths needed as input for Stark width calculations were obtained from the atomic structure data base TOPbase. If we need to interpolate these Stark widths at different temperatures for the studied transitions of Ar iv, we use a simple and accurate fitting formula based on a least-squares method. The calculated values were compared to the existing experimental and calculated Stark width values.

Stark broadening for Br VI and Kr V-VII lines in hot star atmospheres

Context. This paper provides missing Stark broadening of the Br VI and Kr V-VII lines recently discovered in the ultraviolet spectrum of the hot white dwarf RE 0503–289 and investigates the importance of the Stark broadening mechanism versus the Doppler mechanism in that star. As far as we know, this is the first time that Stark widths of Br VI and Kr V-VII lines have been calculated. Aims. The recent discovery of new lines of Br VI and Kr V-VII encourages us to provide their Stark broadening to enrich the STARK-B database and for use in interpretations of the observed spectra. Methods. We used our quantum mechanical method for calculating electron impact broadening to provide Stark widths. The method starts with an evaluation of the structure and collision parameters using the University College London codes SUPERSTRUCTURE/DISTORTED WAVE/JAJOM, which are adapted to the line broadening calculations. We then used the collision parameters to calculate the line widths using our programs. Results. We provide the missing widths of 35 lines of Br VI and Kr V-VII at different electron temperatures and at density Ne = 1017 cm−3. We find that the Stark broadening mechanism is preponderant compared to the Doppler one for almost all the plasma conditions of the considered DO white dwarf atmospheres.

Forty Years of the Applications of Stark Broadening Data Determined with the Modified Semiempirical Method

The aim of this paper is to analyze the various uses of Stark broadening data for non-hydrogenic lines emitted from plasma, obtained with the modified semiempirical method formulated 40 years ago (1980), which are continuously implemented in the STARK-B database. In such a way one can identify research fields where they are applied and better see the needs of users in order to better plan future work. This is done by analysis of citations of the modified semiempirical method and the corresponding data in international scientific journals, excluding cases when they are used for comparison with other experimental or theoretical Stark broadening data or for development of the theory of Stark broadening. On the basis of our analysis, one can conclude that the principal applications of such data are in astronomy (white dwarfs, A and B stars, and opacity), investigations of laser produced plasmas, laser design and optimization and their applications in industry and technology (ablation, laser melting, deposition, plasma during electrolytic oxidation, laser micro sintering), as well as for the determination of radiative properties of various plasmas, plasma diagnostics, and investigations of regularities and systematic trends of Stark broadening parameters.

The Spectroscopic Atomic and Molecular Databases at the Paris Observatory

This paper is intended to give a comprehensive overview of the current status and developments of the Paris Observatory STARK-B, MOLAT and SESAM databases which can be interrogated thanks to interoperability tools. The STARK-B database provides shifting and broadening parameters of different atomic and ionic transitions due to impacts with charged particles (the so-called Stark broadening) for different temperatures and densities. The spectroscopic MOLAT and SESAM databases provide the wavelengths, the oscillator strengths or Einstein spontaneous emission coefficients of H 2 , CO and isotopologues molecules.

Virtual Laboratory Astrophysics and the STARK-B database VAMDC node: a resource for electron and ion impact widths and shifts of isolated lines

SynopsisStark broadening theories and calculations can now be considered as mature. The fast computers allow to calculate a great number of atomic data needed for accurate spectroscopic diagnostics and modeling, such as for stellar atmospheres and envelopes, laboratory and technological plasmas, and laser equipments. Thus the access to these data via an on line database is essential. The STARK-B database is intended to meet this need. It contains calculated widths and shifts of isolated atomic lines due to electron and ion impacts. It is still under development and will be presented at the Conference.

Modeling Mg ii h, k and Triplet Lines at Solar Flare Ribbons

Abstract Observations from the Interface Region Imaging Spectrograph often reveal significantly broadened and non-reversed profiles of the Mg ii h, k and triplet lines at flare ribbons. To understand the formation of these optically thick Mg ii lines, we perform plane-parallel radiative hydrodynamics modeling with the RADYN code, and then recalculate the Mg ii line profiles from RADYN atmosphere snapshots using the radiative transfer code RH. We find that the current RH code significantly underestimates the Mg ii h and k Stark widths. By implementing semiclassical perturbation approximation results of quadratic Stark broadening from the STARK-B database in the RH code, the Stark broadenings are found to be one order of magnitude larger than those calculated from the current RH code. However, the improved Stark widths are still too small, and another factor of 30 has to be multiplied to reproduce the significantly broadened lines and adjacent continuum seen in observations. Nonthermal electrons, magnetic fields, three-dimensional effects, or electron density effects may account for this factor. Without modifying the RADYN atmosphere, we have also reproduced non-reversed Mg ii h and k profiles, which appear when the electron beam energy flux is decreasing. These profiles are formed at an electron density of ∼8 × 1014 cm−3 and a temperature of ∼1.4 × 104 K, where the source function slightly deviates from the Planck function. Our investigation also demonstrates that at flare ribbons the triplet lines are formed in the upper chromosphere, close to the formation heights of the h and k lines.

Stark Widths of Yb III and Lu IV Spectral Lines

Rare Earth Elements are important for stellar atmosphere analysis but the corresponding Stark broadening data are scarce. For Yb III and Lu IV theoretical as well as experimental data on Stark broadening parameters of spectral lines are absent in the literature. Using the modified semiempirical method of Dimitrijević and Konjević, we determined Stark widths for four Yb III and four Lu IV transitions, belonging to the erbium isoelectronic sequence. The obtained results are also used to discuss similarities between homologous transitions in the erbium isoelectronic sequence. We note as well that calculated widths will be implemented in the STARK-B database which is also a part of the Virtual Atomic and Molecular Data Center.

Stark Broadening of Cr III Spectral Lines: DO White Dwarfs

Using the modified semiempirical method of Dimitrijević and Konjević, Stark widths have been calculated for six Cr III transitions, for an electron density of 10 17 cm ‒ 3 and for temperatures from 5000–80,000 K. Results have been used for the investigation of the influence of Stark broadening on spectral lines in cool DO white dwarf atmospheres. Calculated Stark widths will be implemented in the STARK-B database, which is also a part of the Virtual Atomic and Molecular Data Center (VAMDC).

Stark Broadening of Se IV, Sn IV, Sb IV and Te IV Spectral Lines

Stark broadening parameters, line width and shift, are needed for investigations, analysis and modelling of astrophysical, laboratory, laser produced and technological plasmas. Especially in astrophysics, due to constantly increasing resolution of satellite borne spectrographs, and large terrestrial telescopes, data on trace elements, which were previously insignificant, now have increasing importance. Using the modified semiempirical method of Dimitrijević and Konjević, here, Stark widths have been calculated for 2 Se IV, 6 Sn IV, 2 Sb IV and 1 Te IV transitions. Results have been compared with existing theoretical data for Sn IV. Obtained results will be implemented in the STARK-B database, which is also a part of Virtual atomic and molecular data center (VAMDC).

Stark Widths of Na IV Spectral Lines

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/).

Semiclassical Stark Broadening Parameters of Ar VII Spectral Lines

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).

On the Stark broadening of Cr VI spectral lines in astrophysical plasma

Stark broadening parameters for Cr VI lines have been calculated using semiclassical perturbation method for conditions of interest for stellar plasma. Here are presented, as an example of obtained results, Stark broadening parameters for electron- and proton-impact broadening for Cr VI 4s 2S-4p 2P° λ = 1430 Å and Cr VI 4p 2P°-5s 2S λ = 611.8 Å multiplets. The obtained results are used to demonstrate the importance of Stark broadening of Cr VI in DO white dwarf atmospheres. Also the obtained results will enter in STARK-B database which is included in Virtual Atomic and Molecula Data Center - VAMDC.

Stark Widths of Spectral Lines of Neutral Neon

In order to complete Stark broadening data for Ne I spectral lines which are needed for analysis of stellar atmospheres, collisional widths and shifts (the so-called Stark broadening parameters) of 29 isolated spectral lines of neutral neon have been determined within the impact semiclassical perturbation method. Calculations have been performed for the broadening by collisions with electrons, protons and ionized helium for astrophysical applications, and for collisions with ionized neon and argon for laboratory plasma diagnostics. The shifts have been compared with existing experimental values. The obtained data will be included in the STARK-B database, which is a part of the Virtual Atomic and Molecular Data Center – VAMDC.

On the Stark Broadening of Lu III Spectral Lines

The electron-impact widths for 27 Lu III spectral lines have been calculated by using the modified semiempirical method. Calculations have been also performed with the published relativistic Hartree-Fock oscillator strengths and additionally, with the approximate formula of Cowley. With the obtained results, the influence of Stark broadening on Lu III lines was investigated in the spectra of A-type stars. The obtained data will be included in the STARK-B database, which is part of the Virtual Atomic and Molecular Data Center – VAMDC.

The STARK-B database VAMDC node: a repository for spectral line broadening and shifts due to collisions with charged particles

Accurate spectroscopic diagnostics and modeling require the knowledge of numerous collisional line profiles. Access to such data via an online database has become indispensable. The STARK-B database is aimed at meeting these needs for widths and shifts of isolated lines of neutral and ionized elements due to electron and ion impacts. This database of the Paris Observatory is a result of scientific cooperation between S Sahal-Bréchot (LERMA) and M S Dimitrijević (AOB). Access to it is free, and it was opened online at the end of 2008. STARK-B is a node of the Virtual Atomic and Molecular Data Centre (VAMDC) and thus complies with VAMDC and Virtual Observatory standards. VAMDC is a European Union-funded collaboration among groups involved in the generation and use of interoperable atomic and molecular data. STARK-B now contains all our semiclassical-perturbation (SCP) calculated data for more than 123 neutral or ionized elements as published in international refereed journals. It is devoted to modeling and spectroscopic diagnostics of stellar atmospheres and envelopes, laboratory plasmas, laser equipment, and technological plasmas. Hence, the range of temperatures and densities covered by the tables is broad and depends on the ionization degree of the radiating atom. The modified semiempirical (MSE) results of calculations have begun to be implemented. In this paper, we highlight the key points of the method and the assumptions used in the calculations, which have lately been revisited. Then we present the database and its recent developments, as well as our ongoing work and our plans for the future.

Widths and Shifts of Isolated Lines of Neutral and Ionized Atoms Perturbed by Collisions With Electrons and Ions: An Outline of the Semiclassical Perturbation (SCP) Method and of the Approximations Used for the Calculations

“Stark broadening” theory and calculations have been extensively developed for about 50 years. The theory can now be considered as mature for many applications, especially for accurate spectroscopic diagnostics and modeling, in astrophysics, laboratory plasma physics and technological plasmas, as well. This requires the knowledge of numerous collisional line profiles. In order to meet these needs, the “SCP” (semiclassical perturbation) method and numerical code were created and developed. The SCP code is now extensively used for the needs of spectroscopic diagnostics and modeling, and the results of the published calculations are displayed in the STARK-B database. The aim of the present paper is to introduce the main approximations leading to the impact of semiclassical perturbation method and to give formulae entering the numerical SCP code, in order to understand the validity conditions of the method and of the results; and also to understand some regularities and systematic trends. This would also allow one to compare the method and its results to those of other methods and codes. 1

The STARK-B database as a resource for “STARK” widths and shifts data: State of advancement and program of development

“Stark” broadening theories and calculations have been extensively developed for about 50 years and can now be applied to many needs, especially for accurate spectroscopic diagnostics and modeling. This requires the knowledge of numerous collisional line profiles. Nowadays, the access to such data via an online database becomes essential. STARK-B is a collaborative project between the Astronomical Observatory of Belgrade and the Laboratoire d’Étude du Rayonnement et de la matière en Astrophysique (LERMA). It is a database of calculated widths and shifts of isolated lines of atoms and ions due to electron and ion collisions (impacts). It is devoted to modeling and spectroscopic diagnostics of stellar atmospheres and envelopes, laboratory plasmas, laser equipments and technological plasmas. Hence, the domain of temperatures and densities covered by the tables is wide and depends on the ionization degree of the considered ion. STARK-B has been fully opened since September 2008 and is in free access.The first stage of development was ended in autumn 2012, since all the existing data calculated with the impact semiclassical-perturbation method and code by Sahal-Bréchot, Dimitrijević and coworkers have now been implemented. We are now beginning the second stage of the development of STARK-B. The state of advancement of the database and our program of development are presented here, together with its context within VAMDC. VAMDC (Virtual Atomic and Molecular Data Center) is an international consortium which has built a secure, documented, flexible interoperable platform e-science permitting an automated exchange of atomic and molecular data.

Virtual Laboratory Astrophysics: the STARK-B database for spectral line broadening by collisions with charged particles and its link to the European project VAMDC

Atomic physics in plasmas has been an essential tool for many years. Accurate spectroscopic diagnostics and modeling require the knowledge of numerous collisional line profiles. "Stark broadening" theories and calculations have been extensively developed for about 50 years. Nowadays, the access to such data via an on line database becomes essential. The aim of STARK-B is to reply to this need. It is a collaborative project between the Astronomical Observatory of Belgrade (AOB) and the "Laboratoire d'Étude du Rayonnement et de la matière en Astrophysique" (LERMA) of the Paris Observatory and CNRS. It is a database of widths and shifts of isolated lines of atoms and ions due to electron and ion impacts that we have calculated and published in international refereed journals (more than 150 papers by Dimitrijević & Sahal-Bréchot, and colleagues). It is devoted to modeling and spectroscopic diagnostics of stellar atmospheres and envelopes, laboratory plasmas, magnetic fusion plasmas, laser equipments and technological plasmas. Hence, the domain of temperatures and densities covered by the tables is wide and depends on the ionization degree of the considered ion. The STARK-B database is in free access and is is a part of VAMDC: the Virtual Atomic and Molecular Data Centre is an European Union funded collaboration between groups involved in the generation and use of atomic and molecular data. VAMDC aims to build a secure, documented, flexible and interoperable e-science environment-based interface to existing atomic and molecular data. STARK-B and its VAMDC context are presented in this paper.

Virtual laboratory astrophysics : The STARK-B database

Stark broadening theories and calculations have been exten- sively developed for about 50 years. The theory can now be considered as mature for many applications, especially for accurate spectroscopic diagnostics and modelling. This requires the knowledge of numerous collisional line profiles, especially for very low abundant atoms and ions which are used as probes for modern spectroscopic diagnostics in as- trophysics. Nowadays, the access to such data via an on line database becomes essential. STARK-B (http://stark-b.obspm.fr )i s a col- laborative project between the Astronomical Observatory of Belgrade and the Laboratoire d'´ Etude du Rayonnement et de la matiere en Astrophysique (LERMA). It is a database of calculated widths and shifts of isolated lines of atoms and ions due to electron and ion col- lisions (impacts). It is devoted to modelling and spectroscopic diag- nostics of stellar atmospheres and envelopes, laboratory plasmas, laser equipments and technological plasmas. Hence, the domain of temper- atures and densities covered by the tables is wide and depends on the ionization degree of the considered ion. The STARK-B database is a part of VAMDC (Virtual Atomic and Molecular Data Centre, http:// www.vamdc.eu), which is an European Union funded collaboration be- tween groups involved in the generation and use of atomic and molec- ular data. VAMDC aims to build a secure, documented, flexible and interoperable e-science environment-based interface to existing atomic and molecular data.

Stark Broadening of In III Lines in Astrophysical and Laboratory Plasma

Abstract In the deeper layers of hot stellar photospheres the Stark widths of spectral lines can be comparable and even larger than the thermal Doppler widths. Using the semiclassical perturbation method, we investigate the influence of the collisions with charged particles for the In III lines. We determine a number of Stark broadening parameters important in the atmospheres of A-type stars and white dwarfs. Also, the obtained results are compared with the available experimental data. The results will be included in the STARK-B database, the Virtual Atomic and Molecular Data Center and the Serbian Virtual Observatory.