Stark broadening data for spectral lines of rare-earth elements: Nb III

The electron-impact widths for 15 doubly charged Nb ion lines have been theoretically determined by using the modified semiempirical method. Using the obtained results, we considered the influence of the electron-impact mechanism on line shapes in spectra of chemically peculiar stars and white dwarfs.Comment: 10 pages, 2 figures, 1 table, accepted in Advances in Space Researc

Influence of long-range potentials on Stark broadening of spectral lines of plasma

U rаdu је izvršеnа dеtаlјnа аnаlizа krеtаnjа nаеlеktrisаnе čеsticе pоd uticајеm Kulоnоvоg, pоlаrizаciоnоg i kvаdrupоlnоg pоtеnciјаlа i dоbiјеni su аnаlitički izrаzi zа pаrаmеtrе putаnjе čеsticе. Таkоđе su ispitаni uslоvi zа еgzistеnciјu kritičnоg sudаrnоg pаrаmеtrа, kојi rаzdvаја putаnjе kоје zаvršаvајu u аtоmu оd оnih kоје оdlаzе u bеskоnаčnоst, i rаzrаđеnе mеtоdе zа njеgоvо nаlаžеnjе. Rеzultаti оvоg ispitivаnjа su primеnjеni nа tеоriјu Štаrkоvоg širеnjа (širеnjа spеktrаlnih liniја pоd uticајеm sudаrа sа nаеlеktrisаnim čеsticаmа), pri čеmu је pоsеbnа pаžnjа pоsvеćеnа аdiјаbаtskој grаnici i kvаzistаtičkој i sudаrnој аprоksimаciјi. Izvеdеnа је mоdifikаciја funkciја Štаrkоvоg širеnjа i pоkаzаnо је dа је nајvеći uticај zаkrivlјеnоsti putаnjе nа njih, u blizini kritičnоg sudаrnоg pаrаmеtrа, kојi rаzdvаја putаnjе kоје zаvršаvајu u аtоmu оd оnih kоје оdlаzе u bеskоnаčnоst. Prоmеnа u vеličini funkciја Štаrkоvоg širеnjа ćе nајvišе uticаti nа pаrаmеtrе Štаrkоvоg širеnjа kоd liniја zа kоје је, pri nајvеrоvаtniјој brzini, uticај dоprinоsа nееlаstičnih sudаrа dоminаntаn а еfеktivnа pоlаrizаbilnоst vеlikа. Таkоđе је аnаlizirаnа primеnа sеmiеmpiriјskоg аprоksimаtivnоg prilаzа zа izrаčunаvаnjе pаrаmеtаrа Štаrkоvоg širеnjа zа višеstrukо nаеlеktrisаnе еmitеrе, pri čеmu је izvršеnа mоdifikаciја sеmiklаsičnе tеоriје. Usrеdnjеni оdnоs еkspеrimеntаlnih i tеоriјskih rеzultаtа је 0.75 zа sеmiеmpiriјski, 1.47 zа sеmiklаsični а 1.04 zа mоdifikоvаni sеmiklаsični prilаz.A detailed analysis of the motion of a charged particle under the influence of Coulomb, polarization, and quadrupolar potential has been performed, and analytical expressions for particle path parameters have been obtained. Also, conditions for existence of a critical impact parameter, which separates paths ending in the atom from those going to infinity, have been examined, and methods for its determination have been elaborated. Results of this investigations have been applied to the theory of Stark broadening (broadening of spectral lines under the influence of collisions with charged particles), where a special attention has been paid to the adiabatic limit, and to quasistatic and impact approximations. Modification of Stark broadening functions has been performed and it has been demonstrated that the biggest influence of path curvature on them, is in the vicinity of the critical impact parameter, which separates paths ending in the atom from those going to infinity. The change in the values of the Stark broadening functions will have the largest influence on Stark broadening parameters for lines for which, at the most probable velocity, influence of the contribution of inelastic collisions is dominant and effective polarizability large. The application of semiempirical approximative approach for calculation of Stark broadening parameters for multiply charged emitters, has been analyzed as well, and the modification of semiclassical theory has been performed. The averaged ratio of experimental and theoretical results is 0.75 for semiempirical, 1.47 for semiclassical, and 1.04 for modified semiclassical approach

Stark widths of Sc IV spectral lines within 4s-4p transition array

Stark full widths at half maximum of six 4s - 4p Sc IV spectral lines, broadened by collisions with electrons, have been calculated for electron density of 1017 cm-3 by using the modified semi-empirical method. The results are provided for temperatures from 10 000 K to 160 000 K. They are used also to discuss the similarities of Sc IV spectral lines within multiplet, supermultiplet and transition array. Obtained results will be included in the STARK-B database which is also a part of Virtual atomic and molecular data center (VAMDC)

Numerical Calculation of Hubble Hierarchy Parameters and Observational Parameters of Inflation

We present results obtained by a software we developed for computing observational cosmological inflation parameters: the scalar spectral index ($n_s$) and the tensor-to-scalar ratio ($r$) for a standard single field and tachyon inflation, as well as for a tachyon inflation in the second Randall-Sundrum model with an additional radion field. The calculated numerical values of observational parameters are compared with the latest results of observations obtained by the Planck Collaboration. The program is written in C/C++. The \textit{GNU Scientific Library} is used for some of the numerical computations and R language is used for data analysis and plots.Comment: 8 pages, 5 figures, based on talk presented at The 10th Jubilee Conference of the Balkan Physical Union (BPU10), 26-30 August 2018 (Sofia, Bulgaria

Inflationary RSII Model with a Matter in the Bulk and Exponential Potential of Tachyon Field

In this paper we study a tachyon cosmological model based on dynamics of a 3-brane in the second Randall-Sundrum (RSII) model extended to include matter in the bulk. The presence of matter in the bulk changes warp factor which leads to modification of inflationary dynamics. The additional brane behaves effectively as a tachyon. We calculate numerically observation parameters of inflation: the scalar spectral index ($n_s$) and the tensor-to-scalar ratio ($r$) for the exponential potential of tachyon field.Comment: 9 pages, 1 figure, will be published in the Special Issue of Facta Universitatis, Series: Physics, Chemistry and Technology devoted to the SEENET-MTP Balkan Workshop BSW2018 (3-14 June 2018

The OIV 1407.3\AA /1401.1\AA\ emission-line ratio in a plasma

Line ratio of O IV 1407.3 \AA/1401.1 \AA\- is calculated using mostly our own atomic and collisional data. Energy levels and oscillator strengths needed for this calculation have been calculated using a Hartree-Fock relativistic (HFR) approach. The electron collision strengths introduced in the statistic equilibrium equations are fitted by polynomials for different energies. Comparison has also been made with available theoretical results. The provided line ratio has been obtained for a set of electron densities from $10^{8}$ cm$^{-3}$ to $10^{13}$ cm$^{-3}$ and for a fixed temperature of 50 000 K.Comment: 6 pages, 1 figure, 2 tables. Accepted for publication in Advances in Space Researc

The STARK-B database as a resource for \textquotedblleft STARK" widths and shifts data: State of advancement and program of development

\textquotedblleft 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'\'Etude du Rayonnement et de la mati\`ere 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-Br\'echot, Dimitrijevi\'c 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.Comment: 4 pages, in press in Advances in Space Researc

Stark Broadening in Compact Stars: Xe VI Lines

International audienceWe will consider Stark broadening of non hydrogenic spectral lines in the impact approximation in compact stars: pre-white dwarf and white dwarf atmospheres. In order to show an example, Stark broadening parameters have been calculated, using the impact semiclassical perturbation approach for four Xe VI spectral lines. Obtained results have been used to demonstrate the influence of Stark broadening in DA and DB white dwarf atmospheres

INFLATIONARY RSII MODEL WITH A MATTER IN THE BULK AND EXPONENTIAL POTENTIAL OF TACHYON FIELD

In this paper, we study a tachyon cosmological model based on the dynamics of a 3-brane in the second Randall-Sundrum (RSII) model extended to include matter in the bulk. The presence of matter in the bulk changes the warp factor which leads to the modification of inflationary dynamics. The additional brane behaves effectively as a tachyon. We calculate numerically observation parameters of inflation: the scalar spectral index (ns) and the tensor-to-scalar ratio (r) for the exponential potential of the tachyon field