Chemical evolution of the Magellanic Clouds. VI. Chemical composition of nine F supergiants from different regions of the large Magellanic Cloud.
Abstract
In an effort to increase the available information on the chemical content of the Magellanic Clouds, we investigated nine F supergiants from the field of the LMC by high-resolution spectroscopy, in order to obtain the elemental abundance ratios for C, O, α-elements, Fe peak and heavy elements. The stars are widely distributed over the LMC. An LTE analysis has given the following results: 1. All investigated stars are metal deficient ([Fe/H] value covers the interval from -0.34dex to -0.14dex; mean value: -0.27dex). 2. The iron abundance appears to be surprisingly uniform, although the stars were chosen in different regions of the LMC. The star-to star scatter is within the observation uncertainty. 3. For all stars[C/Fe]<~0 but still exceeds the value observed in LMC HII regions by +0.2dex. 4. The [O/Fe] ratio is very similar to the one found for the Galactic supergiant Canopus, and the star-to-star scatter is small (σ=0.1dex) 5. Sodium does not seem to be enhanced (in average) in the LMC supergiants. 6. Among α-elements Si, S, Ca and Ti are enhanced in LMC supergiants, but Mg is slightly underabundant (with respect to Fe) when compared with solar value. 7. Heavy s- and r- process elements are overabundant by +0.3dex in average. This overabundance could be somewhat smaller for Eu, a pure r- process element.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- January 1995
- Bibcode:
- 1995A&A...293..347H
- Keywords:
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- STARS: ABUNDANCES;
- STARS: SUPERGIANTS;
- MAGELLANIC CLOUDS;
- GALAXIES: ABUNDANCES