J/A+A/557/A128 Stellar [Fe/H] and [Na/H] in NGC6752 (Carretta, 2013)
The fraction of first and second generation stars in globular clusters.
I. The case of NGC 6752.
Carretta E.
<Astron. Astrophys. 557, A128 (2013)>
=2013A&A...557A.128C 2013A&A...557A.128C
ADC_Keywords: Clusters, globular ; Abundances
Keywords: stars: abundances - stars: Population II - Galaxy: abundances -
Galaxy: stellar content - Galaxy: globular clusters -
Galaxy: globular clusters: individual: NGC 6752
Abstract:
We present a new method to estimate the fraction of stars with
chemical composition of first and second(s) generation(s) currently
hosted in Galactic globular clusters (GCs). We compare cluster and
field stars of similar metallicity in the [Fe/H]-[Na/H] plane. Since
the phenomenon of multiple populations is only restricted to the
cluster environment, the number of GC stars whose location coincides
with that of field stars provides the fraction of first generation
stars in that cluster. By exclusion, the fraction of second generation
stars is derived. We assembled a dataset of 1891 field stars of the
thin disk, thick disk, and halo of the Milky Way in the metallicity
range -3.15≤[Fe/H]≤+0.48dex and with Na abundance from high
resolution spectra. They are mostly dwarfs, but include also giants.
Considering only the range in metallicity spanned by most GCs
extensively studied for the Na-O anticorrelation
(-2.36≤[Fe/H]≤-0.33dex), we have 804 stars. The total sample is
homogeneized by offsets in [Fe/H] and [Na/H] with respect to a
reference sample using the same line list and NLTE correction for Na
adopted in a recent extensive survey of GC stars. This fully accounts
for offsets among analyses due to different temperature scales, line
lists, adopted (or neglected) corrections for departures from LTE. We
illustrate our method estimating the fraction of first and second
generation stars in the well studied GC NGC 6752. As a by-product, the
comparison of [Na/H] values in GC and field stars suggests that at
least two classes of old stellar systems probably contributed to the
halo assembly: one group with characteristics similar to the currently
existing GCs, and the other more similar to the present-day dwarf
satellite galaxies.
Description:
We present the list of (unique) field stars used in the paper, with
atmospheric parameters, [Fe/H], [Na/H].
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 78 1891 ID, coordinates, atmospheric parameters,
[Fe/H] and [Na/H] abundances
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See also:
I/239 : The Hipparcos and Tycho Catalogues (ESA 1997)
J/AJ/120/1841 : Halo & disk stars abundances and kinematics (Fulbright 2000)
J/A+A/354/169 : Metal-poor field stars abundances (Gratton+, 2000)
J/A+A/356/238 : Metal-poor stars atmospheric parameters III (Carretta+ 2000)
J/A+A/404/187 : Equivalent widths for metal-poor stars (Gratton+, 2003)
J/A+AS/141/491 : Chemical composition of halo and disk stars (Nissen+, 2000)
J/A+A/433/185 : 102 F & G dwarfs detailed abundance analysis (Bensby+, 2005)
J/A+A/440/321 : Chemical abundances in 43 metal-poor stars (Jonsell+, 2005)
J/A+A/440/901 : Reddening and metallicity of NGC 6752 (Gratton, 2005)
J/MNRAS/367/1329 : Elemental abundances for 176 stars (Reddy+, 2006)
J/A+A/511/L10 : Abundances and space velocities of 94 stars (Nissen+, 2010)
J/A+A/464/927 : Abundances of red giants in NGC 6752 (Carretta+, 2007)
J/AZh/88/750 : Galactic sub-structures stars abundances (Mishenina+, 2011)
J/A+A/545/A32 : Chemical abundances of 1111 stars (Adibekyan+, 2012)
J/MNRAS/423/2901 : NGC 6752 multiwavelength survey (Thomson+, 2012)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Seq [1/1891] Star Sequential number
6- 15 A10 --- Name Star name (HR, HD, BD, CD, or G identification)
17- 21 F5.2 [cm/s2] logg ?=9.99 Surface gravity
23- 26 I4 K Teff ?=9999 Effective temperature
28- 32 F5.2 [Sun] [Fe/H] [-3.15/0.48] Average [Fe/H] (2)
34- 38 F5.2 [Sun] [Na/H] [-3.44/0.94] Average [Na/H] (2)
40- 41 A2 --- Code Sample code (1)
43- 48 I6 --- Hip Hipparcos (Cat. I/239) number
50- 51 I2 h RAh Right ascension (J2000.0)
53- 54 I2 min RAm Right ascension (J2000.0)
56- 63 F8.5 s RAs Right ascension (J2000.0)
65 A1 --- DE- Declination sign (J2000.0)
66- 67 I2 deg DEd Declination (J2000.0)
69- 70 I2 arcmin DEm Declination (J2000.0)
72- 78 F7.4 arcsec DEs Declination (J2000.0)
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Note (1): Codes as follows:
G = Gratton et al., 2003, Cat. J/A+A/404/187
CA = Carretta et al., 2000, Cat. J/A+A/356/238
GR = Gratton et al., 2000, Cat. J/A+A/354/169
N = Nissen & Schuster 2010, J/A+A/511/L10
F = Fullbright 2000, Cat. J/AJ/120/1841
H = Hanson et al., 1998AJ....116.1286H 1998AJ....116.1286H
GE = Gehren et al., 2006A&A...451.1065G 2006A&A...451.1065G
J = Jonsell et al., 2005, Cat. J/A+A/440/321
M3 = Mishenina et al., 2003, Cat. J/AZh/47/422
A = Adibekyan et al., 2012, Cat. J/A+A/545/A32
R = Reddy et al., 2006, Cat. J/MNRAS/367/1329
M1 = Mishenina et al., 2011, Cat. J/AZh/88/750
B = Bensby et al., 2005, Cat. J/A+A/433/185
C = Chen et al., 2000, Cat. J/A+AS/141/491
AV = more than one sample
Note (2): values with offset to our scale (as defined by the G sample:
Gratton et al. 2003, Cat. J/A+A/404/187)
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Acknowledgements:
Eugenio Carretta, eugenio.carretta(at)oabo.inaf.it
(End) Patricia Vannier [CDS] 19-Aug-2013