J/A+A/600/A104 Potassium abundance in 3 globular clusters (Mucciarelli+, 2017)
The potassium abundance in the globular clusters NGC104, NGC6752 and NGC6809.
Mucciarelli A., Merle T., Bellazzini M.
<Astron. Astrophys. 600, A104 (2017)>
=2017A&A...600A.104M 2017A&A...600A.104M (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Stars, population II ; Abundances
Keywords: techniques: spectroscopic - globular clusters: individual: NGC104 -
globular clusters: individual: NGC6752 -
globular clusters: individual: NGC6809 - stars: abundances
Abstract:
We derived Potassium abundances in red giant branch stars in the
Galactic globular clusters NGC 104 (144 stars), NGC 6752 (134 stars)
and NGC 6809 (151 stars) using high-resolution spectra collected with
FLAMES at the ESO - Very Large Telescope. In the considered samples we
do not find significant intrinsic spreads in [K/Fe] (confirming the
previous findings by Carretta et al.), at variance with the cases of
the massive clusters NGC 2419 and NGC 2808. Additionally, marginally
significant [K/Fe]-[O/Fe] anti-correlations are found in NGC 104 and
NGC 6809, and [K/Fe]-[Na/Fe] correlations are found in NGC 104 and
NGC 6752. No evidence of [K/Fe]-[Mg/Fe] anti-correlation are found.
The results of our analysis are consistent with a scenario in which
the process leading to the multi-populations in globular clusters
implies also enrichment in the K abundance, the amplitude of the
associated [K/Fe] enhancement becoming measurable only in stars
showing the most extreme effects of O and Mg depletion. Stars enhanced
in [K/Fe] have been found so far only in clusters harbouring some
Mg-poor stars, while the other globulars, without a Mg-poor
sub-population, show small or null [K/Fe] spreads.
Description:
Potassium-over-iron abundance ratios for red giant branch stars in
three globular clusters obtained using FLAMES spectra: 144 stars in
NGC104, 134 stars in NGC6752, 151 stars in NGC6809. Atmospheric
parameters (effective temperature, surface gravities and
micorturbulent velocities) are provided. All the abundances include
NLTE corrections.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 48 429 Atmospheric parameters and [K/Fe] abundance ratios
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See also:
J/A+A/464/927 : NGC 6752 red giants abundances (Carretta+, 2007)
J/A+A/505/117 : 15 globular clusters red giants abundances (Carretta+, 2009)
J/A+A/505/139 : 17 globular clusters red giants abundances (Carretta+, 2009)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Cluster Cluster name
9- 15 I7 --- ID Star ID (1)
17- 20 I4 K Teff Effective temperature
22- 25 F4.2 [cm/s2] log(g) Surface gravity
27- 30 F4.2 km/s vt Microturbulent velocity
32- 37 F6.2 mA EW Equivalent width of the K line at 7699 Å
39- 43 F5.2 [Sun] [K/Fe] Relative abundance [K/Fe]
45- 48 F4.2 [Sun] e_[K/Fe] Uncertainty on [K/Fe]
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Note (1): from Carretta et al.,
2007, Cat. J/A+A/464/927 (Cl* NGC 6752 CBG NNNNN),
2009a, Cat. J/A+A/505/117 ([CBG2009] NGC NNNN NNNNNNN) and
2009b, Cat. J/A+A/505/139 ([CBG2009] NGC NNNN NNNNNNN).
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Acknowledgements:
Alessio Mucciarelli, alessio.mucciarelli2(at)unibo.it
(End) Patricia Vannier [CDS] 14-Feb-2017