J/MNRAS/475/257 AGB subpopulations in NGC 6397 (MacLean+, 2018)
AGB subpopulations in the nearby globular cluster NGC 6397.
MacLean B.T., Campbell S.W., De Silva G.M., Lattanzio J., D'Orazi V.,
Cottrell P.L., Momany Y., Casagrande L.
<Mon. Not. R. Astron. Soc., 475, 257-265 (2018)>
=2018MNRAS.475..257M 2018MNRAS.475..257M (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Stars, giant ; Photometry, UBVRI ;
Photometry, infrared ; Abundances
Keywords: stars: abundances - stars: AGB and post-AGB - Galaxy: abundances -
Galaxy: formation - globular clusters: general
Abstract:
It has been well established that Galactic Globular clusters (GCs)
harbour more than one stellar population, distinguishable by the
anticorrelations of light-element abundances (C-N, Na-O, and Mg-Al).
These studies have been extended recently to the asymptotic giant
branch (AGB). Here, we investigate the AGB of NGC 6397 for the first
time. We have performed an abundance analysis of high-resolution
spectra of 47 red giant branch (RGB) and eight AGB stars, deriving Fe,
Na, O, Mg, and Al abundances. We find that NGC 6397 shows no evidence
of a deficit in Na-rich AGB stars, as reported for some other GCs -
the subpopulation ratios of the AGB and RGB in NGC 6397 are identical,
within uncertainties. This agrees with expectations from stellar
theory. This GC acts as a control for our earlier work on the AGB of
M4 (with contrasting results), since the same tools and methods were
used.
Description:
Our stellar targets were selected from the NGC 6397 photometric data
set of Momany et al. (2003A&A...407..303M 2003A&A...407..303M, UBVI from the ESO/MPG WFI,
see Table 1).
High-resolution spectra were collected in 2015 July using 2dF+HERMES
on the Anglo-Australian Telescope which provides R=28000 spectra
in four narrow windows; blue (4715-4900Å), green
(5649-5873Å), red (6478-6737Å), and infrared
(7585-7887Å)
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 79 57 NGC 6397 target details
table5.dat 90 57 Stellar parameters and derived chemical
abundances for each star in NGC 6397
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See also:
J/A+A/527/A148 : NGC6397 red giants chemical composition (Lind+, 2011)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Star Star identification number from
Momany et al. (2003A&A...407..303M 2003A&A...407..303M)
7- 9 A3 --- Type [AGB RGB] Type
11- 26 A16 ---- 2MASS 2MASS ID (HHMMSSss+DDMMSSs)
28- 32 I5 --- L11 ?=- Lind et al. (2011, Cat. J/A+A/527/A148)
ID, [LPC2009] NNNNNNN in Simbad
34- 38 F5.2 mag Vmag V magnitude from
Momany et al. (2003A&A...407..303M 2003A&A...407..303M)
40- 44 F5.2 mag Bmag B magnitude from
Momany et al. (2003A&A...407..303M 2003A&A...407..303M)
46- 50 F5.2 mag Umag ?=- U magnitude from
Momany et al. (2003A&A...407..303M 2003A&A...407..303M)
52- 56 F5.2 mag Imag ?=- I magnitude from
Momany et al. (2003A&A...407..303M 2003A&A...407..303M)
58- 62 F5.2 mag Jmag ?=- 2MASS J magnitude (Cat. VII/233)
64- 68 F5.2 mag Hmag ?=- 2MASS H magnitude (Cat. VII/233)
70- 73 F4.2 mag Kmag ?=- 2MASS K magnitude (Cat. VII/233)
75- 79 F5.2 km/s RV Radial velocity
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Star Star identification number from
Momany et al. (2003A&A...407..303M 2003A&A...407..303M)
7- 9 A3 --- Type [AGB RGB] Type
11- 14 I4 J Teff Effective temperature
16- 19 F4.2 [cm/s2] logg Surface gravity
21- 24 F4.2 km/s vt Micro-turbulent velocity
26- 30 F5.2 [-] [FeI/H] Abundance [FeI/H]
32- 35 F4.2 [-] e_[FeI/H] rms uncertainty on [FeI/H] (1)
37- 41 F5.2 [-] [FeII/H] Abundance [FeII/H]
43- 46 F4.2 [-] e_[FeII/H] rms uncertainty on [FeII/H] (1)
48- 52 F5.2 [-] [O/H] Abundance [O/H]
54- 57 F4.2 [-] e_[O/H] rms uncertainty on [O/H] (1)
59- 63 F5.2 [-] [Na/H] Abundance [Na/H]
65- 68 F4.2 [-] e_[Na/H] rms uncertainty on [Na/H] (1)
70- 74 F5.2 [-] [Mg/H] Abundance [Mg/H]
76- 79 F4.2 [-] e_[Mg/H] rms uncertainty on [Mg/H] (1)
81- 85 F5.2 [-] [Al/H] Abundance [Al/H]
87- 90 F4.2 [-] e_[Al/H] rms uncertainty on [Al/H] (1)
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Note (1): Abundance uncertainties reflect line-to-line scatter (1σ),
and do not take atmospheric sensitivities into account.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 24-Mar-2021