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Titel
Influence of improved Stark broadening data on chromium spectral lines
VerfasserChougule, Abhishek
Begutachter / BegutachterinnenPrzybilla, Norbert ; Dimitrijevic, Milan ; Marleau, Francine
Betreuer / BetreuerinnenPrzybilla, Norbert ; Dimitrijevic, Milan
Erschienen2018
HochschulschriftInnsbruck, Univ., Masterarb., 2018
Datum der AbgabeSeptember 2018
SpracheEnglisch
DokumenttypMasterarbeit
Schlagwörter (DE)Starkverbreiterung in Sternen / Stark-Verbreiterung von Cr III - und Cr IV -Linien / modifizierte semi-empirische Methode gegen genäherte Methode für Stark-Verbreiterungsberechnungen / Wichtigkeit der Stark-Verbreiterung in hochoberflächigen Gravitationssternen
Schlagwörter (EN)Stark broadening in stars / Stark broadening of Cr III and Cr IV lines / modified semi-empirical method versus approximated method for Stark broadening calculations / importance of Stark broadening in high surface gravity stars
URNurn:nbn:at:at-ubi:1-24912 Persistent Identifier (URN)
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 Das Werk ist frei verfügbar
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Influence of improved Stark broadening data on chromium spectral lines [16.84 mb]
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Zusammenfassung (Deutsch)

Stellar atmosphere modeling and chemical abundance determinations require the knowledge of spectral line shapes. A spectral line is not infinitely sharp but has a finite width and shape, due to various line broadening mechanisms. This phenomenon is known as broadening of spectral lines. Stark broadening of spectral lines results from the perturbation of atomic/ionic energy levels involved in the electronic transition by interaction with charged particles. Spectral lines of chromium (Cr) in various ionization stages have often been observed in stellar spectra but the theoretical data on Stark broadening for them is scarce.

This work focuses on Stark broadening of Cr lines in the ultraviolet (UV) regionof stellar spectra. The work was divided in two parts: (1) calculation of Stark broadeningdata and (2) the study of its influence on spectral line shapes. We have calculated Stark broadening data using the Modified Semi-Empirical approach (MSE) for 4s-4p transition spectral lines in doubly and triply ionized Cr.

We have used ATLAS9 model atmospheres and the line-formation code SURFACE for calculating synthetic spectra of Cr for several stars under consideration. We compared the theoretical Cr spectral lines based on approximate Stark broadening data with those based on MSE broadening tables. The OB-type main-sequence stars Iota Hercules and Upsilon Orionis, and the subdwarf B-stars CD-24 731, HD199112, and Feige 66 were investigated.

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