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J/A+A/615/A17     Red giant Aluminium abundances in NGC 2808   (Carretta+, 2018)

Aluminium abundances in five discrete stellar populations of the globular cluster NGC 2808. Carretta E., Bragaglia A., Lucatello S., Gratton R.G., D'Orazi V, Sollima A. <Astron. Astrophys. 615, A17 (2018)> =2018A&A...615A..17C (SIMBAD/NED BibCode)
ADC_Keywords: Abundances ; Clusters, globular ; Spectroscopy ; Stars, giant Keywords: stars: abundances - stars: atmospheres - stars: Population II - globular clusters: general - globular clusters: individual: NGC 2808 Abstract: We observed a sample of 90 red giant branch (RGB) stars in NGC 2808 using FLAMES/GIRAFFE and the high resolution grating with the set up HR21. These stars have previous accurate atmospheric parameters and abundances of light elements. We derived aluminium abundances for them from the strong doublet AlI 8772-8773 Angstrom as in previous works of our group. In addition, we were able to estimate the relative CN abundances for 89 of the stars from the strength of a large number of CN features. When adding self consistent abundances from previous UVES spectra analysed by our team, we gathered [Al/Fe] ratios for a total of 108 RGB stars in NGC 2808. The full dataset of proton-capture elements is used to explore in details the five spectroscopically detected discrete components in this globular cluster. We found that different classes of polluters are required to reproduce the (anti)-correlations among all proton-capture elements in the populations P2, I1, and I2 with intermediate composition. This is in agreement with the detection of lithium in lower RGB second generation stars, requiring at least two kind of polluters. To have chemically homogeneous populations the best subdivision of our sample is into six components, as derived from statistical cluster analysis. By comparing different diagrams [element/Fe] vs [element/Fe] we show for the first time that a simple dilution model is not able to reproduce all the sub-populations in this cluster. Polluters of different masses are required. NGC 2808 is confirmed to be a tough challenge to any scenario for globular cluster formation. Description: FLAMES-GIRAFFE HR21 spectra of 90 RGB stars in the GC NGC2808 are analyzed and Al, (C)N abundances are derived. These abundances are used in connection with previous data on Fe, Na, and O to study the multiple populations in this cluster. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 49 90 Names, coordinates, Vmag, RV table3.dat 40 140 Group classification, [Al/Fe], [N/Fe]
See also: J/ApJ/810/148 : Red giant abundances in NGC 2808 (Carretta, 2015) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
3- 7 I5 --- Star Star ID, Cl* NGC 2808 PKD NNNNN in Simbad 9- 18 F10.6 deg RAdeg Right ascension (J2000.0) 20- 29 F10.6 deg DEdeg Declination (J2000.0) 31- 35 F5.1 --- S/N Signal-to-noise ratio 37- 42 F6.2 km/s HRV Heliocentric radial velocity 44- 49 F6.3 mag Vmag V magnitude
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
3- 7 I5 --- Star Star ID, Cl* NGC 2808 PKD NNNNN in Simbad 9 A1 --- Flag [UG] U (UVES) or G (GIRAFFE) spectrum 11 I1 --- Group [0/5] Group classification from Carretta (2015ApJ...810..148C, Cat. J/ApJ/810/148) (1) 13- 18 F6.3 [-] [Al/Fe] ? Abundance ratio [Al/Fe] 20- 24 F5.3 [-] e_[Al/Fe] ? Error on [Al/Fe] 26- 31 F6.3 [-] [N/Fe] ? Abundance ratio [N/Fe] 33- 37 F5.3 [-] e_[N/Fe] ? Error on [N/Fe] 39- 40 I2 --- NCN Number of CN features used
Note (1): Group classification as follows: 0 = not classified 1 = P1, with primordial or almost abundance ratio 2 = P2, with primordial or almost primordial abundance ratio 3 = I1, with intermediate composition 4 = I2, with intermediate composition 5 = E, with severely extreme changes from the original composition
Acknowledgements: Eugenio Carratta, eugenio.carretta(at)oabo.inaf.it
(End) Patricia Vannier [CDS] 12-Feb-2018
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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