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Astron. Astrophys. 363, 815-820 (2000)
Analysis of the hyperfine and isotopic structure of Ga II in the optical spectrum of ![[FORMULA]](img1.gif)
Cnc and HR 7775
K. Nielsen,
H. Karlsson and
G.M. Wahlgren
Atomic Spectroscopy Group, Department of Physics, University of Lund Box 118, 221 00 Lund, Sweden (krister.nielsen@fysik.lu.se)
Received 11 April 2000 / Accepted 3 July 2000
Abstract
Spectra of the HgMn stars ![[FORMULA]](img2.gif)
Cnc
and HR 7775 have been analyzed, under the assumption of local
thermodynamic equilibrium (LTE), with respect to the abundance and
isotopic mixture of gallium. The primary purpose of the investigation
was to level the contradictory results obtained using spectral lines
in different spectral regions (Smith, 1996). The analysis has been
performed by GaII lines in the optical region including
hyperfine and isotopic components from new Fourier Transform
Spectrometer measurements (Karlsson & Litzen, 2000). Gallium has,
for both stars, been determined to be overabundant by two orders of
magnitude compared to the sun, using oscillator strengths derived by
Ryabchikova & Smirnov (1994). The difference in abundance obtained
using spectral lines in the UV and the visual spectral region is
unexplainable by accounting for hyperfine and isotopic structure.
Astrophysical log gf values have been determined for the
GaII 5p - 5d transitions at 5360, 5363 and
5421 Å.
Key words: atomic
processes 
line: profiles
stars:
abundances
stars: chemically
peculiar
stars: individual: Cnc, HR 7775
Send offprint requests to: K. Nielsen
Contents
- 1. Introduction
- 2. Observational data
- 3. Atomic data
- 4. Spectrum analysis
- 5. Conclusions
- Acknowledgements
- References
© European Southern Observatory (ESO) 2000
Online publication: December 11, 2000
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