J/A+A/515/A28 Abundances of dwarfs and giants in 2 open clusters (Pace+, 2010)
Abundances and physical parameters for stars in the open clusters NGC 5822 and
IC 4756.
Pace G., Danziger J., Carraro G., Melendez J., Francois P., Matteucci F.,
Santos N.C.
<Astron. Astrophys. 515, A28 (2010)>
=2010A&A...515A..28P 2010A&A...515A..28P
ADC_Keywords: Clusters, open ; Stars, dwarfs ; Stars, giant ; Abundances ;
Equivalent widths ; Spectroscopy
Keywords: open clusters and associations: individual: NGC 5822 -
open clusters and associations: individual: IC 4756 -
stars: abundances - stars: rotation
Abstract:
It has been suggested that the classical chemical analysis may be
affected by systematic errors that would introduce abundance
differences between dwarfs and giants. For some elements, the
abundance difference could be real. We address the issue by observing
2 solar-type dwarfs in NGC 5822 and 3 in IC 4756, and comparing their
composition with that of 3 giants in either of the aforementioned
clusters. We determine iron abundance and stellar parameters for dwarf
stars. Then, abundances of calcium, sodium, nickel, titanium,
aluminium, chromium, and silicon were determined for both giants and
dwarfs. The standard equivalent width analysis was performed
differentially with respect to the Sun. We find an iron abundance for
dwarf stars equal to solar to within the margins of error for IC 4756,
and slightly above for NGC 5822 ([Fe/H]=0.01 and 0.05dex
respectively). We show that, for sodium, silicon, and titanium,
abundances of giants are significantly higher than those of the dwarfs
of the same cluster (about 0.15, 0.15, and 0.35dex). Other elements
may also undergo some enhanced, but all within 0.1dex.
Description:
The table contains equivalent width measurements for each individual
line of the adopted line list, and the corresponding abundance
measurement. The data analysed consist of UVES@VLT spectra of 5 dwarf
and 6 giants members of NGC 5822 and IC 4756. The resolution is of
about R=100000 in the red arm, which covers the range from 4800 to
6800Å, which include all the lines analysed. The S/N is of
about 100 for dwarfs, about 60 only for TATM 11003, and about 150 for
giants.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 88 11 List of stars studied
table2.dat 36 1468 Equivalent widths and abundances from individual lines
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Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Star name, as used in table2 (1)
17- 37 A21 --- SName Simbad name
43- 44 I2 h RAh Simbad Hour of Right Ascension (J2000.0)
46- 47 I2 min RAm Simbad Minute of Right Ascension (J2000.0)
49- 53 F5.2 s RAs Simbad Second of Right Ascension (J2000.0)
54 A1 --- DE- Simbad Sign of the Declination (J2000.0)
55- 56 I2 deg DEd Simbad Degree of Declination (J2000.0)
58- 59 I2 arcmin DEm Simbad Arcminute of Declination (J2000.0)
61- 64 F4.1 arcsec DEs Simbad Arcsecond of Declination (J2000.0)
66- 70 F5.2 mag Bmag Simbad B band magnitude
72- 76 F5.2 mag Vmag Simbad V band magnitude
79- 82 I4 K Teff Effective temperature (from spectroscopy)
85- 88 F4.2 [cm/s2] logg Gravity
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Note (1): Used names:
* HER = Herzog and Sanders (1975A&AS...19..211H 1975A&AS...19..211H) (dwarfs)
* TATM = Twarog, Anthony-Twarog and McClure (1993PASP..105...78T 1993PASP..105...78T) (dwarfs)
* IC5746No = Kopff (1943AN....274...69K 1943AN....274...69K) (giants)
* NGC5822No = Bozkurt (1974RMxAA...1...89B 1974RMxAA...1...89B) (giants)
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Star name, as in "stars.dat" file
14- 20 F7.2 0.1nm lambda Line wavelength
22- 24 A3 --- Ion Element and ionization stage
26- 30 F5.1 0.1pm EW Line equivalent width
32- 36 F5.2 [Sun] [X/H] Abundance relative to the Sun
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Acknowledgements:
Giancarlo Pace, gpace(at)astro.up.pt
(End) Giancarlo Pace [CAUP, Portugal], Patricia Vannier [CDS] 12-Feb-2010