# Stark Broadening of Co II Lines in Stellar Atmospheres

^{1}

^{2}

^{3}

^{*}

## Abstract

**:**

**Dataset:**Supplementary File

**Dataset License:**CC BY 4.0

## 1. Introduction

## 2. Dataset and Methods of Research

^{56}Fe or other more neutron-rich heavy isotopes.

^{7}(

^{M}L)nl subconfigurations, which are built on the parent terms (

^{M}L) in Co III, and transitions involving these levels dominate the emission spectrum of Co II. The subconfigurations 3d

^{6}(

^{M}L)4snl in the “doubly excited” system are built on the (

^{M}L) grandparent terms in Co IV, and they were not part of our interests. The Stark widths analyzed and used here [2,3] were calculated for multiplets created from a normal system of configurations, 3d

^{7}(

^{M}L)nl, which is well known for nl = 4 s and 4p, and according to observations those transitions are expected to be in pure LS coupling [28]. The predicted accuracy of the MSE method is around ±50 percent, but even in the cases of emitters with complex spectra, for example Xe II and Kr II, this method often gives better agreement with experiments, with relative error less than ±30 percent [30,31]. Of course, the used model also has some error bars, but our qualitative conclusions are confirmed with calculations using three different papers with model atmospheres for DA and DB white dwarfs and for A type stars. A high precision can not be achieved since we used the published models and included Stark broadening of spectral lines a posteriori. However, the presence of Stark broadening influence electron density and temperature and, consequently, on parameters of the model of atmosphere and for the best precision the Stark broadening data should be introduced a priori, during the calculation of model atmosphere.

_{eff}= 10,000 K [32]. In the case of DA and DB dwarfs, the results of similar investigations are presented in Figure 1 and Figure 2, using the model atmospheres from Wickramasinghe [33]. For the presentation of this dependence according to different T

_{eff}or log g for DB stars, appropriate model atmospheres from Koester were used [34].

## 3. Results and Discussion

^{4}P)4s

^{3}P–(

^{4}P)4p

^{3}D

^{o}and (

^{4}F)4p

^{3}G

^{o}–(

^{4}F)5s

^{3}F, respectively, are in the ultraviolet part of the spectrum, while the last two lines considered by us, λ9519 and λ9969, from multiplets (

^{4}F)5s

^{5}F–(

^{4}F)5p

^{5}G

^{o}and (

^{4}F)5s

^{3}F–(

^{4}F)5p

^{5}F

^{o}, respectively, are in the infrared part of the spectrum. In Figure 1a,b, this analysis is done for DA WD model atmospheres [33] with parameters T

_{eff}= 15,000 K and log g = 8. Stark and Doppler broadening as a function of optical depth τ in the atmosphere at 5150 Å are shown in Figure 1a, and as a function of layer temperature in Figure 1b. The same comparisons but for DB white dwarf atmosphere model with the same parameters are shown in Figure 2a,b. In Figure 3a,b, we can see the behaviors in the function of logarithm of Rosseland optical depth and temperature in the stellar atmospheres for an A-type model atmosphere [32] with parameters log g = 4.5 and T

_{eff}= 10,000 K. Stark width in comparison with Doppler width increases as wavelength increases, because if a wavelength is larger than the corresponding atomic energy levels are closer and because of that, the perturbation of the emitter/absorber is larger and the emitted spectral line is broader. We notice also that Stark widths are proportional to λ

^{2}, while Doppler widths are proportional to λ [3]. For the last line, λ9959, the point where Stark width reaches Doppler width is deeper in the atmosphere than for the previous line, λ9519, because the Stark width values for this line are smaller since the corresponding atomic energy levels are further away than in the previous case and the perturbation is smaller.

_{eff}= 14,000 K where it is several thousand kelvins to the model with T

_{eff}= 30,000 K, where it is larger than 10,000 K.

_{eff}of 12,000 and 30,000 K, with two different values of log g for each temperature. We can see that electron-impact broadening becomes more important in DB white dwarf atmosphere than thermal broadening with the increase in surface gravity.

## 4. Conclusions

## Supplementary Materials

## Author Contributions

## Funding

## Conflicts of Interest

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**Figure 1.**(

**a**) Stark and Doppler broadening for spectral lines λ2533.2, λ2709, λ9519 and λ9969 as a function of optical depth in the atmosphere of a hydrogen-rich (DA) white dwarf. Model atmosphere with T

_{eff}= 15,000 K and log g = 8 is taken from [33]. (

**b**) Same as Fig1a, but as a function of atmospheric layer temperature instead of optical depth.

**Figure 3.**(

**a**) Same as in Figure 1a and Figure 2a, but as a function of logarithm of Rosseland optical depth, for the model atmosphere of A-type star [32] with model parameters log g = 4.5 and T

_{eff}= 10,000 K. (

**b**) Same as Figure 3a, but as a function of atmospheric layer temperature instead of optical depth.

**Figure 4.**Comparison of Stark and Doppler broadening influence on Co II line λ9969 in the atmosphere of DA and DB white dwarfs, respectively, as a function of optical depth. Calculations have been performed for model atmospheres of DA and DB white dwarfs [33] with the same model parameters as in previous figures, T

_{eff}= 15,000 K and log g = 8.

**Figure 5.**Stark and Doppler broadening of Co II spectral line λ9969 as a function of temperature of atmospheric layers in a DB white dwarf. Stark widths are shown for models [32] with five different values of effective temperature, T

_{eff}= 14,000–30,000 K and log g = 8.

**Figure 6.**Stark and Doppler broadening of Co II spectral line λ9969 as a function of temperature of atmospheric layers in a DB white dwarf for two different values of model gravity, log g = 7 and log g = 8, each with two extremal values of effective temperatures, T

_{eff}= 12,000 K and T

_{eff}= 30,000 K.

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**MDPI and ACS Style**

Majlinger, Z.; Dimitrijević, M.S.; Srećković, V.A. Stark Broadening of Co II Lines in Stellar Atmospheres. *Data* **2020**, *5*, 74.
https://doi.org/10.3390/data5030074

**AMA Style**

Majlinger Z, Dimitrijević MS, Srećković VA. Stark Broadening of Co II Lines in Stellar Atmospheres. *Data*. 2020; 5(3):74.
https://doi.org/10.3390/data5030074

**Chicago/Turabian Style**

Majlinger, Zlatko, Milan S. Dimitrijević, and Vladimir A. Srećković. 2020. "Stark Broadening of Co II Lines in Stellar Atmospheres" *Data* 5, no. 3: 74.
https://doi.org/10.3390/data5030074