J/A+A/505/L13 Lithium in globular NGC 6397 (Gonzalez Hernandez+, 2009)
Lithium in the Globular Cluster NGC 6397:
Evidence for dependence on evolutionary status.
Gonzalez Hernandez J.I., Bonifacio P., Caffau E., Steffen M., Ludwig H.-G.,
Behara N.T., Sbordone L., Cayrel R., Zaggia S.
<Astron. Astrophys. 505, L13 (2009)>
=2009A&A...505L..13G 2009A&A...505L..13G
ADC_Keywords: Clusters, globular ; Stars, dwarfs ; Stars, giant ;
Equivalent widths ; Effective temperatures
Keywords: stars: abundances - stars: atmospheres -
stars: fundamental parameters - stars: population II -
Galaxy: globular clusters: individual: NGC 6397
Abstract:
Most globular clusters are believed to host a single stellar
population. They can thus be considered a good place to study the
Spite plateau and to search for possible evolutionary modifications of
the Li content.
We want to determine the Li content of subgiant (SG) and main sequence
(MS) stars of the old, metal-poor globular cluster NGC 6397. This work
was aimed not only at studying possible Li abundance variations but
also to investigate the cosmological Li discrepancy.
Description:
Photometric data of the dwarf and subgiant stars of the globular
cluster NGC 6397. We also provide the signal-to-noise of the spectra,
the 3D and 1D Hα-based effective temperatures, 3D Li abundances,
and the equivalent widths and errors: dEWa: Error of the equivalent
width measurements estimated from a fitting routine that uses as free
parameters the velocity shift, the continuum location, and the
equivalent width of the Li line. dEWb: Error of the equivalent width
associated to the signal-to-noise ratio and the wavelength dispersion
of the spectra, derived using Cayrel's formula (Cayrel, 1988, IAU
Symp. 132: The Impact of Very High S/N Spectroscopy on Stellar
Physics, 132, 345).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 80 163 Effective temperature, Equivalent Width and
Li abundances in stars of NGC 6397
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See also:
J/A+A/287/769 : UV photometry of NGC 6397 (Burgarella+ 1994)
J/PASP/106/404 : NGC 6535 BV CCD photometry (Sarajedini, 1994)
J/ApJS/99/637 : Equivalent widths for 54 red giants (Norris+ 1995)
J/PASP/108/682 : Low-Mass Stars in Outer Field in NGC 6397 (Mould+, 1996)
J/A+AS/122/1 : BV photometry of variables in NGC 6397 (Kaluzny, 1997)
J/A+A/425/509 : VI photometry of NGC 6397 (Andreuzzi+, 2004)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name Name of the star (MSSNNNNNN or SGBNNNNNN)
11- 12 I2 h RAh Right ascension (J2000)
14- 15 I2 min RAm Right ascension (J2000)
17- 21 F5.2 s RAs Right ascension (J2000)
23 A1 --- DE- Declination sign (J2000)
24- 25 I2 deg DEd Declination (J2000)
27- 28 I2 arcmin DEm Declination (J2000)
30- 33 F4.1 arcsec DEs Declination (J2000)
35- 39 F5.2 mag Vmag V magnitude in the Johnson system
41- 45 F5.3 mag B-V ? B-V magnitude in the Johnson system
47- 49 I3 -- SNR Signal-to-noise ratio (1)
51- 54 I4 K Teff(3D) 3D Hα-based Effective temperature
56- 59 I4 K Teff(1D) 1D Hα-based Effective temperature
61- 65 F5.2 0.1pm EW Equivalent width of Li 6708 line (in mÅ)
67- 70 F4.2 0.1pm e_EWa rms uncertainty in the equivalent width
measurements estimated from a fitting
routine (2)
72- 75 F4.2 0.1pm e_EWb rms uncertainty in the equivalent width
associated to S/N ratio and dispersion of
the spectra (3)
77- 80 F4.2 [---] A(Li) 3D,NLTE Li abundance (log scale, H=12)
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Note (1): Dimensionless parameter
Note (2): Uncertainty in the equivalent width measurements estimated from a
fitting routine that uses as free parameters the velocity shift, the
continuum location, and the equivalent width of the Li line.
Note (3): Error of the equivalent width associated to the signal-to-noise
ratio and the wavelength dispersion of the spectra, derived using
Cayrel's formula (Cayrel 1988, IAU Symp., 132, 345).
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Acknowledgements:
Jonay I. Gonzalez Hernandez, jonay(at)astrax.fis.ucm.es
References:
Bonifacio et al., 2002A&A...390...91B 2002A&A...390...91B
(End) Patricia Vannier [CDS] 04-Sep-2009