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J/A+A/567/A72 Stellar parameters and anticorrelated abundances (Gruyters+, 2014)
The following files can be converted to FITS (extension .fit or fit.gz)
stars.dat anticorr.dat
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Query from: http://vizier.cds.unistra.fr/viz-bin/VizieR?-source=J/A+A/567/A72
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Beginning of ReadMe :J/A+A/567/A72 Stellar parameters and abundances in NGC 6752 (Gruyters+, 2014)
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Atomic diffusion and mixing in old stars.
V. A deeper look into the globular cluster NGC 6752.
Gruyters P., Nordlander T., Korn A.J.
<Astron. Astrophys. 567, A72 (2014)>
=2014A&A...567A..72G
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ADC_Keywords: Abundances ; Clusters, globular ; Models, atmosphere ;
Photometry, uvby ; Spectroscopy
Keywords: stars: abundances - stars: atmospheres -
stars: fundamental parameters -
globular cluster: individual: NGC 6752 - techniques: spectroscopic
Abstract:
Abundance trends in heavier elements with evolutionary phase have been
shown to exist in the globular cluster NGC 6752. These trends are a
result of atomic diffusion and additional (non-convective) mixing.
Studying such trends can provide us with important constraints on the
extent to which diffusion modifies the internal structure and surface
abundances of solar-type, metal-poor stars.
Taking advantage of a larger data sample, we investigate the reality
and the size of these abundance trends and address questions and
potential biases associated with the various stellar populations that
make up NGC 6752.
We perform an abundance analysis by combining photometric and
spectroscopic data of 194 stars located between the turnoff point and
the base of the red giant branch. Stellar parameters are derived from
uvby Stromgren photometry. Using the quantitative-spectroscopy package
SME, stellar surface abundances for light elements such as Li, Na, Mg,
Al, and Si as well as heavier elements such as Ca, Ti, and Fe are
derived in an automated way by fitting synthetic spectra to individual
lines in the stellar spectra, obtained with the VLT/FLAMES-GIRAFFE
spectrograph.
Based on uvby Stromgren photometry, we are able to separate three
stellar populations in NGC 6752 along the evolutionary sequence from
the base of the red giant branch down to the turnoff point. We find
weak systematic abundance trends with evolutionary phase for Ca, Ti,
and Fe which are best explained by stellar-structure models including
atomic diffusion with efficient additional mixing. We derive a new
value for the initial lithium abundance of NGC 6752 after correcting
for the effect of atomic diffusion and additional mixing which falls
slightly below the predicted standard BBN value.
We find three stellar populations by combining photometric and
spectroscopic data of 194 stars in the globular cluster NGC 6752.
Abundance trends for groups of elements, differently affected by
atomic diffusion and additional mixing, are identified. Although the
statistical significance of the individual trends is weak, they all
support the notion that atomic diffusion is operational along the
evolutionary sequence of NGC 6752.
Description:
Coordinates, photometric parameters, stellar parameters and abundances
of anticorrelated elements for 193 stars. Additionally, photometric
assignments of chemical populations are supplied.