Stark Broadening Effect in Stellar Atmospheres: Nd
                    <scp>ii</scp>
                    Lines

Popović, L. Č.; Simić, Saša; Milovanović, N.; Dimitrijević, M. S.

doi:10.1086/321778

Cited by 37 publications

(21 citation statements)

References 14 publications

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“…For example, the importance of the Stark broadening effect in stellar atmospheres of A and B type stars was studied by Popović et al [9] and Simić et al [10]. Based on Si VI lines, Hamdi et al [11] demonstrated that the Stark broadening mechanism is dominant in broad regions in the studied atmospheres of DO white dwarfs.…”

Section: Introductionmentioning

confidence: 99%

Stark Widths of Ar II Spectral Lines in the Atmospheres of Subdwarf B Stars

Hamdi

Nessib

Dimitrijević

2017

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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.

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Section: Introductionmentioning

confidence: 99%

Stark Widths of Ar II Spectral Lines in the Atmospheres of Subdwarf B Stars

Hamdi

Nessib

Dimitrijević

2017

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“…There are different methods of computing the Stark broadening Γ function of the spectral lines (e.g. Cowley 1971;Kurucz et al 1974;Popovic et al 2001). Kurucz et al (1974) and Cowley (1971) describe two separate methods of calculating the Stark broadening Γ independent of temperature, while the Popovic et al (2001) method scales the Kurucz et al (1974) broadening by the square root of the temperature.…”

Section: Broadening Of He I Linesmentioning

confidence: 99%

“…Cowley 1971;Kurucz et al 1974;Popovic et al 2001). Kurucz et al (1974) and Cowley (1971) describe two separate methods of calculating the Stark broadening Γ independent of temperature, while the Popovic et al (2001) method scales the Kurucz et al (1974) broadening by the square root of the temperature. For most of the spectral lines, the ATLAS9 and SYNTHE codes use the Kurucz et al (1974) method for calculating the Stark broadening.…”

Section: Broadening Of He I Linesmentioning

confidence: 99%

On the nature of sn stars

Saffe

Levato

2014

A&A

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The sn stars were first discoved by Abt & Levato when studying the spectral types in different open clusters. These stars present sharp Balmer lines, sharp metallic lines (C II, Si II, Ca II, Ti II, Fe II), and broad coreless He I lines. Some of the sn stars seem to be related to CP stars. Initially Abt & Levato proposed a shell-like nature to explain the sn stars, although this scenario was subsequently questioned. There is no general agreement about their origin. We aim to derive abundances for a sample of 9 stars, including sn and non-sn stars, to determine the possible relation between sn and CP stars and compare their chemical abundances. That most sn stars belong to open clusters allows us to search for a possible relation with fundamental parameters, including the age and rotation. We also study the possible contribution of different effects to the broad He I lines observed in these stars, such as Stark broadening and the possible He-stratification. Effective temperature and gravity were estimated by Strömgren photometry and then refined by requiring ionization and excitation equilibrium of Fe lines. We derived the abundances by fitting the observed spectra with synthetic spectra using an iterative procedure with the SYNTHE and ATLAS9 codes. We derived metallic abundances of 23 different chemical elements for 9 stars and obtained low projected rotational velocities for the sn stars in our sample (v sin i up to 69 km s −1 ). We also compared 5 stars that belong to the same cluster (NGC 6475) and show that the sn characteristics appear in the 3 stars with the lower rotational velocity. However, the apparent preference of sn stars for objects with the lower v sin i values should be taken with caution due to the small number of objects studied here. We analysed the photospheric chemical composition of sn stars and show that approximately ∼40% of them display chemical peculiarities (such as He-weak and HgMn stars) within a range of temperature of 10 300 K−14 500 K. However, there are also sn stars with solar or nearly-solar (i.e. non-CP) chemical composition. We have studied the possible contribution of different processes to the broad He I lines present in the sn stars. Although NLTE effects could not be completely ruled out, it seems that NLTE is not directly related to the broad He I profiles observed in the sn stars. The broad-line He I 4026 Å is the clearest example of the sn characteristics in our sample. We succesfully fit this line in 4 out of 7 sn stars by using the appropriate Stark broadening tables, while small differences appear in the other 3 stars. Studying the plots of abundance vs. depth for the He I lines resulted in some sn stars probably being stratified in He. However, a further study of variability in the He I lines would help for determining whether a possible non-uniform He superficial distribution could also play a role in these sn stars. We conclude that the broad He I lines that characterize the sn class could be modelled (at least in some of these stars) by the usual radiati...

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“…Dimitrijević 1989;Popović et al 1999Popović et al , 2001. This broadening mechanism also may be important in the case of cooler stars, e.g.…”

Section: Introductionmentioning

confidence: 98%

The electron-impact broadening parameters for Co III spectral lines

Tankosic

Popović

Dimitrijević

2003

A&A

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Abstract. In hot star atmospheres, the Stark broadening mechanism is the main pressure broadening mechanism. An interesting application where such a mechanism is of interest is the modeling and investigation of hot star spectra, stellar atmospheres and subphotospheric layers. Consequently, for the investigation and modeling of the Hg-Mn star and other type of hot star atmospheres, the Stark broadening parameters for Co III spectral lines may be of interest.Here we present Stark broadening data for 20 Co III spectral lines (from a 6 D -z 6 D o and a 6 D -z 6 F o Co III multiplets), as a function of temperature, calculated by using the modified semi-empirical approach. The importance of the electron-impact effect in the case of the Co III 194.98 nm line for several stellar atmosphere models has been tested.

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Stark Broadening Effect in Stellar Atmospheres: Nd ii Lines

Cited by 37 publications

References 14 publications

Stark Widths of Ar II Spectral Lines in the Atmospheres of Subdwarf B Stars

Stark Widths of Ar II Spectral Lines in the Atmospheres of Subdwarf B Stars

On the nature of sn stars

The electron-impact broadening parameters for Co III spectral lines

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