J/AJ/134/1216 Abundances of NGC 7142, 6939, and IC 4756 stars (Jacobson+, 2007)
Na, al, and O abundances of open clusters NGC 7142, NGC 6939, and IC 4756.
Jacobson H.R., Friel E.D., Pilachowski C.A.
<Astron. J., 134, 1216-1230 (2007)>
=2007AJ....134.1216J 2007AJ....134.1216J
ADC_Keywords: Clusters, open ; Abundances
Keywords: Galaxy: abundances -
open clusters and associations: individual
(NGC 7142, NGC 6939, IC 4756) - stars: abundances
Abstract:
We present an analysis of echelle spectra of stars in three open
clusters obtained with the Hydra multiobject spectrograph on the WIYN
3.5m telescope. Abundances of Fe, O, Si, Ca, Na, Al, and Ni have been
determined via equivalent width analysis and spectrum synthesis. Mean
abundances for each cluster are compared to those of previous studies
and of other clusters in the literature, with emphasis on exploring
the enhancements of Na and Al seen in many open clusters. All three
clusters show enhanced values of [Na/Fe] and [Al/Fe], while the
abundances of Fe, O, Si, and Ca are consistent with their ages and
locations in the Galactic disk.
Description:
Single-order echelle spectra of stars in each cluster were obtained
with the Hydra multiobject spectrograph on the WIYN 3.5m telescope in
the fall of 2005.
Objects:
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RA (2000) DE Designation(s)
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21 45 09 +65 46.5 NGC 7142 = Cl Collinder 442
20 31 30 +60 39.7 NGC 6939 = Cl Melotte 231
18 38 31.2 +05 29 24 IC 4756 = Cl Melotte 210
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 72 44 NGC 7142, NGC 6939 and IC 4756 stars observed
table4.dat 46 927 Equivalent widths
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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- 8 A8 --- Cluster Cluster name
10- 13 I4 --- Star Star number within the cluster (1)
15- 18 I4 --- WEBDA ? WEBDA star number
20- 24 F5.2 mag Vmag V magnitude
26- 29 F4.2 mag B-V B-V colour index
31- 34 F4.2 mag V-K V-K colour index
36- 39 F4.2 mag J-K J-K colour index (2MASS)
41- 43 I3 --- S/N Signal-to-noise ratio
(Average of Na and Al data)
45- 49 F5.1 km/s RV Radial velocity
51- 56 F6.2 km/s RV2 ? Radial velocity from Mermilliod & Mayor,
1990A&A...237...61M 1990A&A...237...61M
58- 69 A12 --- Memb Membership, with comments
72 A1 --- EW [*] indicates equivalent width data in table4
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Note (1): Identification lists are:
* For NGC 7142, Identification from Crinklaw & Talbert,
(1991PASP..103..536C 1991PASP..103..536C), Cl* NGC 7142 CT NNN in Simbad
* For NGC 6939, Identification from Kustner (1923VeBon..18....1K 1923VeBon..18....1K),
NGC 6939 NNN in Simbad
* For IC 4756, Identification from Kopff (1943AN....274...69K 1943AN....274...69K)
IC 4756 NNNN in Simbad
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Cluster Cluster name
10- 12 I3 --- Star Star number within the cluster
14- 18 A5 --- Ion Ion identification
20- 27 F8.3 0.1nm lambda Wavelength in Angstroms
29- 33 F5.3 eV ExPot Excitation potential
35- 40 F6.3 [-] log(gf) Log of the oscillator strength
42- 46 F5.1 10-13m EW ? Equivalent width
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 04-Oct-2009