J/ApJ/713/L1 Lithium and proton-capture elements in 47 Tuc (D'Orazi+, 2010)
Lithium and proton-capture elements in globular cluster dwarfs:
the case of 47 Tuc.
D'Orazi V., Lucatello S., Gratton R., Bragaglia A., Carretta E., Shen Z.,
Zaggia S.
<Astrophys. J., 713, L1-L5 (2010)>
=2010ApJ...713L...1D 2010ApJ...713L...1D
ADC_Keywords: Abundances ; Clusters, globular ; Effective temperatures ;
Stars, dwarfs
Keywords: globular clusters: individual (NGC 104) - stars: abundances -
stars: individual (Population II)
Abstract:
Previous surveys in a few metal-poor globular clusters (GCs) showed
that the determination of abundances for Li and proton-capture
elements offers a key tool to address the intracluster pollution
scenario. In this Letter, we present Na, O, and Li abundances in a
large sample of dwarf stars in the metal-rich GC 47 Tucanae. We found
a clear Na-O anticorrelation, in good agreement with what obtained for
giant members by Carretta et al. (2009, Cat. J/A+A/505/117). While
lithium and oxygen abundances appear to be positively correlated with
each other, there is a large scatter, well exceeding observational
errors, and no anticorrelation with sodium. These findings suggest
that Li depletion, due to mechanisms internal to the stars (which are
cooler and more metal-rich than those on the Spite plateau), combines
with the usual pollution scenario responsible for the Na-O
anticorrelation.
Description:
We retrieved from the ESO Archive FLAMES-Giraffe spectra (MEDUSA
configuration) of 109 unevolved members of the metal-rich GC 47 Tuc
(Program 081.D-0287; PI: Z. Shen). The observations were carried out
in Service mode in 2008 August-September; gratings HR15n (R∼17000),
HR18 (R∼18400), and HR20A (R∼16000) were used to cover LiI (6707Å),
OI (7771, 7773, 7774Å), and NaI (8183, 8194Å) features,
respectively.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 80 100 Properties of target stars
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See also:
VII/202 : Globular Clusters in the Milky Way (Harris, 1997)
J/A+A/505/117 : Abundances of red giants in 15 GCs (Carretta+, 2009)
J/A+A/503/545 : Equivalent widths of Li, Na, Fe, Ca in NGC 6397 (Lind+, 2009)
J/AJ/135/1551 : Abundances of stars in 47 Tuc (Koch+, 2008)
J/AJ/125/197 : CN abundances of the 47 Tuc main sequence (Harbeck+, 2003)
J/A+AS/117/227 : Dwarf effective temperatures (Alonso+ 1996)
J/A+AS/106/161 : (V,I) photometry in NGC 6356 and 47 Tuc (Bica+ 1994)
J/ApJS/85/293 : HST Observations of core of 47 Tuc (de Marchi+ 1993)
J/PASP/99/739 : BV photometry in 4 fields of 47 Tuc (Hesser+, 1987)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID [1/114] Stellar identification number
(<[DLG2010] NNN> in Simbad)
5- 11 F7.5 deg RAdeg Right Ascension (J2000)
13- 20 F8.4 deg DEdeg Declination (J2000)
22- 27 F6.3 mag Vmag The V band magnitude (1)
29- 34 F6.3 mag Bmag The B band magnitude (1)
36- 39 I4 K Teff Effective temperature (1)
41- 44 F4.2 [cm/s2] log(g) Log of the gravity
46- 50 F5.3 [-] lognO ?=9.999 Log of the oxygen number abundance (2)
52- 56 F5.3 [-] e_lognO ?=9.999 Error in LognO
58- 62 F5.3 [-] lognNa ?=9.999 Log of the sodium number abundance (2)
64- 68 F5.3 [-] e_lognNa ?=9.999 Error in LognNa
70- 74 F5.3 [-] lognLi ?=9.999 Log of the lithium number abundance (2)
76- 80 F5.3 [-] e_lognLi ?=0.000 Error in LognLi
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Note (1): We obtained initial effective temperatures (Teff) from the
de-reddened (E(B-V)=0.04; Harris 1996, see Cat. VII/202) B-V colors
(data are from unpublished photometry by Y. Momany (2004, private
communication) and the calibration by Alonso et al. (1996, Cat.
J/A+AS/117/227). The adopted values were derived from a relation
between V magnitude and color-based Teff. See section 2 for further
details.
Note (2): the Solar values are:
lognO = 8.79; lognNa = 6.21; lognLi = 2.78±0.08
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 16-Apr-2012