J/MNRAS/446/3556 O, Na, Ba and Eu abundances in open clusters (MacLean+, 2015)
O, Na, Ba and Eu abundance patterns in open clusters.
MacLean B.T., De Silva G.M., Lattanzio J.
<Mon. Not. R. Astron. Soc., 446, 3556-3561 (2015)>
=2015MNRAS.446.3556M 2015MNRAS.446.3556M (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Abundances
Keywords: stars: abundances - Galaxy: abundances - Galaxy: formation -
open clusters and associations: general
Abstract:
Open clusters are historically regarded as single-aged stellar
populations representative of star formation within the Galactic disc.
Recent literature has questioned this view, based on discrepant Na
abundances relative to the field, and concerns about the longevity of
bound clusters contributing to a selection bias: perhaps long-lived
open clusters are chemically different to the star formation events
that contributed to the Galactic disc. We explore a large sample of
high-resolution Na, O, Ba and Eu abundances from the literature,
homogenized as much as reasonable including accounting for non-local
thermodynamic equilibrium (NLTE) effects, variations in analysis and
choice of spectral lines. Compared to a template globular cluster and
representative field stars, we find no significant abundance trends,
confirming that the process producing the Na-O anticorrelation in
globular clusters is not present in open clusters. Furthermore,
previously reported Na enhancement of open clusters is found to be an
artefact of NLTE effects, with the open clusters matching a subset of
chemically tagged field stars.
Description:
We sourced high-resolution spectroscopic abundances of Na and O as
well as Ba and Eu in Galactic OCs from the literature, in order to
gather the largest sample size possible. If a study did not measure
either pair of these elements, it was not included in our sample. To
minimize systematic effects and ensure a high level of abundance
accuracy, we limited our data set to studies based on a minimum
spectral resolution of R=20000. Due to the fact that the
anticorrelations in GCs and chemical homogeneity in OCs are observed
as star-to-star abundance variations, we originally limited our OC
sample to clusters where a total of five or more individual stellar
abundances were available.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
clusters.dat 40 21 List of open cluster studied
table2.dat 95 1134 Open cluster sample, with star names as given in
each paper and references for each star
refs.dat 98 25 References
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See also:
J/A+A/360/499 : Equivalent widths of 9 stars of M 67 (Tautvaisiene+, 2000)
J/A+A/431/933 : Abundances of NGC 7789 evolved stars (Tautvaisiene+, 2005)
J/A+A/433/185 : 102 F & G dwarfs detailed abundance analysis (Bensby+, 2005)
J/A+A/562/A71 : Solar neighbourhood dwarfs chemical abund. (Bensby+, 2014)
J/A+A/548/A122 : Berkeley 39 stars photometry & abundances (Bragaglia+, 2012)
J/A+A/489/403 : Line abundances for solar stars (Pace+, 2008)
J/MNRAS/419/1350 : Red giants abundances in 4 open clusters (Reddy+, 2012)
Byte-by-byte Description of file: clusters.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Cluster Cluster name
16- 17 I2 h RAh ? Simbad right ascension (J2000)
19- 20 I2 min RAm ? Simbad right ascension (J2000)
22- 25 F4.1 s RAs ? Simbad right ascension (J2000)
28 A1 --- DE- Simbad declination sign (J2000)
29- 30 I2 deg DEd ? Simbad declination (J2000)
32- 33 I2 arcmin DEm ? Simbad declination (J2000)
35- 36 I2 arcsec DEs ? Simbad declination (J2000)
38- 40 I3 --- Nstar Number of stars for the cluster in table2
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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- 13 A13 --- Cluster Cluster name
15- 25 A11 --- Star Star designation (1)
27- 31 F5.2 [-] [Fe/H] ?=- Metallicity [Fe/H] (2)
33- 36 F4.2 [-] e_[Fe/H] ? rms uncertainty on [Fe/H]
38- 42 F5.2 [-] [O/Fe] ?=- Abundance [O/Fe] (2)
44- 47 F4.2 [-] e_[O/Fe] ? rms uncertainty on [O/Fe]
49- 53 F5.2 [-] [Na/Fe] ?=- Abundance [Na/Fe] (2)
55- 58 F4.2 [-] e_[Na/Fe] ? rms uncertainty on [Na/Fe]
60- 64 F5.2 --- Corr ?=- NLTE correction on Na abundances (3)
66- 69 F4.2 --- e_Corr ? rms uncertainty on NLTE correction
71- 75 F5.2 [-] [Ba/Fe] ?=- Abundance [Ba/Fe] (2)
77- 80 F4.2 [-] e_[Ba/Fe] ? rms uncertainty on [Ba/Fe]
83- 87 F5.2 [-] [Eu/Fe] ?=- Abundance [Eu/Fe] (2)
89- 92 F4.2 [-] e_[Eu/Fe] ?=- rms uncertainty on [Eu/Fe]
94- 95 I2 --- Ref ?=- Reference, in refs.dat file
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Note (1): The last row of every cluster (Star=Avg) is the average abundances
with rms error.
Note (2): Normalized values, corrected for NLTE effects
Note (3): calculated as per Lind et al. (2011A&A...528A.103L 2011A&A...528A.103L) and described
in Section 2.2.
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Ref Reference number
4- 22 A19 --- BibCode BibCode
24- 52 A29 --- Aut Author's name
54- 98 A45 --- Com Comments
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 29-Jun-2015