J/A+A/464/927 Abundances of red giants in NGC 6752 (Carretta+, 2007)
Na-O Anticorrelation and HB.
II. The Na-O anticorrelation in the globular cluster NGC 6752
Carretta E., Bragaglia A., Gratton R.G., Lucatello S., Momany Y.
<Astron. Astrophys. 464, 927 (2007)>
=2007A&A...464..927C 2007A&A...464..927C
ADC_Keywords: Clusters, globular ; Stars, population II ; Abundances ;
Radial velocities
Keywords: stars: abundances - stars: atmospheres - stars: Population II -
Galaxy: globular clusters: general -
Galaxy: globular clusters: individual: NGC 6752
Abstract:
We are studying the Na-O anticorrelation in several globular clusters
of different Horizontal Branch (HB) morphology in order to derive a
possible relation between (primordial) chemical inhomogeneities and
morphological parameters of the cluster population.
We used the multifiber spectrograph FLAMES on the ESO Very Large
Telescope UT2 and derived atmospheric parameters and elemental
abundances of Fe, O and Na for about 150 red giant stars in the
Galactic globular cluster NGC 6752.
The average metallicity we derive is [Fe/H]=-1.56, in agreement with
other results from red giants, but lower than obtained for dwarfs or
early subgiants.
In NGC 6752 there is not much space for an intrinsic spread in
metallicity: on average, the rms scatter in [Fe/H] is
0.037±0.003dex, while the scatter expected on the basis of the major
error sources is 0.039±0.003dex.
The distribution of stars along the Na-O anticorrelation is different
to what was found in the first paper of this series for the globular
cluster NGC 2808: in NGC 6752 it is skewed toward more Na-poor stars,
and it resembles more the one in M 13.
Detailed modeling is required to clarify whether this difference may
explain the very different distributions of stars along the HB.
Description:
Spectra for 151 RGB stars in NGC 6752 were obtained with FLAMES@VLT
using two gratings (HR11, HR13). Abundances of Fe, O, Na were derived
using equivalent widths, model atmospheres and atmospheric parameters
based on photometry.
For each star we give identification, equatorial coordinates, VBJK
magnitudes, S/N, heliocentric radial velocity for both gratings, Teff,
logg, [A/H], vt, [Fe/H], [O/Fe], [Na/Fe]. Equivalent widths are
given in tablea.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 88 151 Identification, equatorial coordinates, VBJK
magnitudes, S/N, heliocentric radial velocity
table3.dat 54 137 Atmospheric parameters and iron abundance
table5.dat 37 137 O and Na abundances
tablea.dat 37 8220 Equivalent widths for 137 objects
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See also:
J/A+A/455/271 : Abundances of red giants in NGC 6441 (Gratton+, 2006)
J/A+A/464/939 : Abundances of red giants in NGC 6218 (Carreta+, 2007)
J/A+A/464/953 : Abundances of red giants in NGC 6441 (Gratton+, 2007)
J/A+A/464/967 : Abundances of red giants in NGC 6388 (Carreta+, 2007)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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2- 6 I5 --- ID Identification (from Momany et al.,
2004A&A...420..605M 2004A&A...420..605M)
8- 9 I2 h RAh Right ascension (J2000.0)
11- 12 I2 min RAm Right ascension (J2000.0)
14- 19 F6.3 s RAs Right ascension (J2000.0)
21 A1 --- DE- Declination sign (J2000.0)
22- 23 I2 deg DEd Declination (J2000.0)
25- 26 I2 arcmin DEm Declination (J2000.0)
28- 32 F5.2 arcsec DEs Declination (J2000.0)
34- 39 F6.3 mag Vmag ? Johnson V magnitude
41- 46 F6.3 mag Bmag ? Johnson B magnitude
48- 53 F6.3 mag Jmag ? 2MASS J magnitude
55- 60 F6.3 mag Kmag ? 2MASS J magnitude
62- 64 I3 --- S/N Signal-to-Noise ratio
66- 71 F6.2 km/s HRV11 ? Heliocentric radial velocity for grating HR11
73- 78 F6.2 km/s HRV13 ? Heliocentric radial velocity for grating HR13
80- 84 A5 --- HR [11,13 ] Grating(s) used
86- 88 A3 --- Flag [F*+, ] Notes (1)
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Note (1): Notes as follows:
F = field star
* = stars with unreliable V-K
+ = not used in analysis
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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2- 6 I5 --- ID Identification (from Momany et al.,
2004A&A...420..605M 2004A&A...420..605M)
8- 11 I4 K Teff Effective temperature
13- 16 F4.2 [cm/s2] logg Gravity
18- 22 F5.2 [Sun] [A/H] Metallicity
24- 27 F4.2 km/s Vt Microturbulent velocity
29- 30 I2 -- o_FeI Number of lines of Fe I
32- 36 F5.2 [Sun] [Fe/H]I Average star [Fe/H]I
38- 41 F4.2 [Sun] e_[Fe/H]I rms uncertainty on [Fe/H]I
43 I1 -- o_FeII ? Number of lines of Fe II
45- 49 F5.2 [Sun] [Fe/H]II ? Average star [Fe/H]II
51- 54 F4.2 [Sun] e_[Fe/H]II ? rms uncertainty on [Fe/H]II
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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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2- 6 I5 --- ID Identification (from Momany et al.,
2004A&A...420..605M 2004A&A...420..605M)
8 I1 --- o_O ? Number of lines of O
10- 14 F5.2 [Sun] [O/Fe] ? Average [O/Fe]
16- 19 F4.2 [Sun] e_[O/Fe] ? rms uncertainty on [O/Fe]
22 I1 --- o_Na ? Number of lines of Na
24- 28 F5.2 [Sun] [Na/Fe] ? Average [Na/Fe]
30- 33 F4.2 [Sun] e_[Na/Fe] ? rms uncertainty on [Na/Fe]
35 I1 --- Flag1 [1/3] Flag for grating (1)
37 I1 -- Flag2 [0/1] Flag for measure/limit for O (2)
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Note (1): Flags for grating as follows:
1 = HR13 only
2 = both HR11 & HR13
3 = only HR11
Note (2): Flags for measure/limit for O as follows:
0 = O upper limit
1 = O measured
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Byte-by-byte Description of file: tablea.dat
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Bytes Format Units Label Explanations
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1- 5 I5 ---- ID Identification (from Momany et al.,
2004A&A...420..605M 2004A&A...420..605M)
7- 10 F4.1 --- --- Atomic number and ionization stage (1)
13- 19 F7.2 0.1nm lambda Wavelength
21- 24 F4.2 eV EP Excitation potential
26- 31 F6.2 [cm/s2] loggf Surface gravity
33- 37 F5.1 0.1pm EW Equivalent width
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Note (1): NN.1 for neutral, NN.2 for singly ionized
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Acknowledgements:
Eugenio Carretta, eugenio.carretta(at)oabo.inaf.it
References:
Carreta et al., Paper I, NGC 2808 2006A&A...450..523C 2006A&A...450..523C
Gratton et al., Paper III, NGC 6441 2006A&A...455..271G 2006A&A...455..271G, Cat. J/A+A/455/271
Carreta et al., Paper IV, NGC 6218 2007A&A...464..939C 2007A&A...464..939C, Cat. J/A+A/464/939
Gratton et al., Paper V, NGC 6441 2007A&A...464..953G 2007A&A...464..953G, Cat. J/A+A/464/953
Carreta et al., Paper VI, NGC 6388 2007A&A...464..967C 2007A&A...464..967C, Cat. J/A+A/464/967
(End) Patricia Vannier [CDS] 22-Feb-2007