J/AJ/149/15 Spectroscopy of NGC 7789 (Overbeek+, 2015)
NGC 7789: an open cluster case study.
Overbeek J.C., Friel E.D., Jacobson H.R., Johnson C.I., Pilachowski C.A.,
Meszaros S.
<Astron. J., 149, 15 (2015)>
=2015AJ....149...15O 2015AJ....149...15O
ADC_Keywords: Clusters, open ; Stars, giant ; Abundances ; Equivalent widths
Keywords: Galaxy: abundances - stars: abundances -
open clusters and associations: individual: NGC 7789
Abstract:
We have obtained high-resolution spectra of 32 giants in the open
cluster NGC 7789 using the Wisconsin-Indiana-Yale-NOAO Hydra
spectrograph. We explore differences in atmospheric parameters and
elemental abundances caused by the use of the linelist developed for
the Gaia-ESO Survey (GES) compared to one based on Arcturus used in
our previous work. [Fe/H] values decrease when using the GES linelist
instead of the Arcturus-based linelist; these differences are probably
driven by systematically lower (~-0.1dex) GES surface gravities. Using
the GES linelist we determine abundances for 10 elements--Fe, Mg, Si,
Ca, Ti, Na, Ni, Zr, Ba, and La. We find the cluster's average
metallicity [Fe/H]=0.03±0.07dex, in good agreement with literature
values, and a lower [Mg/Fe] abundance than has been reported before
for this cluster (0.11±0.05dex). We also find the neutron-capture
element barium to be highly enhanced--[Ba/Fe]=+0.48±0.08--and
disparate from cluster measurements of neutron-capture elements La and
Zr (-0.08±0.05 and 0.08±0.08, respectively). This is in accordance
with recent discoveries of supersolar Ba enhancement in young clusters
along with more modest enhancement of other neutron-capture elements
formed in similar environments.
Description:
Our data were taken using the Hydra multi-fiber positioner and Bench
Spectrograph on the Wisconsin-Indiana-Yale-NOAO (WIYN; The WIYN
Observatory is a joint facility of the University of
Wisconsin-Madison, Indiana University, Yale University, and the
National Optical Astronomy Observatory) 3.5m, on the nights of 2011
August 20-22. Data were recorded with the STA-1 CCD. The red fiber
cable was used; the echelle grating in 9th order along with the X18
filter resulted in a wavelength range of ∼6050-6380Å with an
effective resolution of R=λ/Δλ∼20000.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 82 39 Properties of sample stars
table2.dat 44 2079 Linelist parameters and equivalent width measurements
table3.dat 65 32 Atmospheric parameters of member stars
table4.dat 31 30 Abundance uncertainties due to atmospheric parameters
table5.dat 55 32 Abundances of α elements
table6.dat 65 32 Other abundances
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/A+A/511/A56 : Abundances of five open clusters (Pancino+, 2010)
J/A+A/431/933 : Abundances of NGC 7789 evolved stars (Tautvaisiene+, 2005)
J/PASP/110/1172 : NGC 7789 radial velocities (Gim+, 1998)
J/PASP/110/1318 : NGC 7789 CCD VI photometry (Gim+, 1998)
J/A+A/295/101 : Variable stars in field of NGC 7789 (Jahn+, 1995)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- Star [2075/12550] Star number (G1)
7- 10 I4 --- K23 ? Star identification from Kustner
(1923VeBon..18....1K 1923VeBon..18....1K), if available
12- 13 I2 h RAh Hour of Right Ascension (B1950.0)
15- 16 I2 min RAm Minute of Right Ascension (B1950.0)
18- 22 F5.2 s RAs Second of Right Ascension (B1950.0)
24 A1 --- DE- Sign of the Declination (B1950.0)
25- 26 I2 deg DEd Degree of Declination (B1950.0)
28- 29 I2 arcmin DEm Arcminute of Declination (B1950.0)
31- 34 F4.1 arcsec DEs Arcsecond of Declination (B1950.0)
36- 41 F6.3 mag Vmag The V-band magnitude (1)
43- 47 F5.3 mag V-I The (V-I) color index (1)
49- 53 F5.3 mag V-K ? The (V-K) color index (2)
55- 59 F5.3 mag J-H ? The (J-H) color index (2)
61- 65 F5.3 mag J-K ? The (J-K) color index (2)
67- 69 I3 --- S/N The signal-to-noise ratio (3)
71- 76 F6.2 km/s RV Radial velocity
78- 82 A5 --- Mm Membership status: M=Member, NM=Non-member,
Bin.M=Binary-member.
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Note (1): V and V-I photometry from Gim et al. 1998 (cat. J/PASP/110/1318).
Photometry is not extinction corrected.
Note (2): JHK photometry from 2MASS (http://www.ipac.caltech.edu/2mass/).
Photometry is not extinction corrected.
Note (3): Per pixel, measured from the final averaged spectrum around
λ6072.
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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- 5 I5 --- Star [2075/12550] Star number (G1)
7- 13 F7.2 0.1nm lambda Wavelength λ; in Å
15- 18 F4.1 --- Ion Ion code (atomic_number.ionization e.g. 26.0=FeI)
20- 24 F5.3 eV EP Excitation potential
26- 31 F6.3 [-] Gloggf ? Log of oscillator strength from Gaia-ESO Survey
(GES) linelist
33- 38 F6.3 [-] Aloggf ? Log of oscillator strength from
Arcturus-based linelist
40- 44 F5.1 10-13m EW Equivalent width; in mÅ (1)
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Note (1): Mg equivalent widths are included because they are referenced in
comparison to the reported abundances determined via spectral synthesis.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- Star [2075/12550] Star number (G1)
7- 10 I4 K GTeff Effective temperature from Gaia-ESO Survey (GES)
linelist
12- 14 F3.1 [cm/s2] Glogg Log of the surface gravity from GES linelist
16- 19 F4.2 km/s Gvt GES microturbulent velocity
21- 25 F5.2 [Sun] G[Fe/H] GES iron abundance
27- 30 F4.2 [Sun] e_G[Fe/H] 1σ error in G[Fe/H]
32- 33 I2 --- GNI Number of GES FeI measurements
35 I1 --- GNII Number of GES FeII measurements
37- 40 I4 K ATeff Arcturus effective temperature
42- 44 F3.1 [cm/s2] Alogg Log of the surface gravity from Arcturus-based
linelist
46- 49 F4.2 km/s Avt Arcturus microturbulent velocity
51- 55 F5.2 [Sun] A[Fe/H] Arcturus iron abundance
57- 60 F4.2 [Sun] e_A[Fe/H] 1σ error in A[Fe/H]
62- 63 I2 --- ANI Number of Arcturus FeI measurements
65 I1 --- ANII Number of Arcturus FeII measurements
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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- 5 I5 --- Star Star number (5594, 7091, 11622) (G1)
7 A1 --- f_Star Display the starting parameters (1)
9- 13 A5 --- Ion Element
15- 19 F5.2 K err.T Uncertainty in elemental abundance due to a
change of +100K in effective temperature
21- 25 F5.2 [cm/s2] err.g Uncertainty in elemental abundance due to a
change of +0.2[cm/s2] in log of surface
gravity (log(g))
27- 31 F5.2 km/s err.vt Uncertainty in elemental abundance due to a
change of +0.1km/s in microturbulent
velocity (vt)
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Note (1): Flags on Star are defined as follows:
a = Starting parameters for 5594 are T=5000K, log(g)=2.5, vt=1.20km/s;
b = Starting parameters for 7091 are T=4200K, log(g)=1.3, vt=1.50km/s;
c = Starting parameters for 11622 are T=4750K, log(g)=2.3, vt=1.45km/s.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Star [2075/12550] Star number (G1)
7- 10 F4.2 [Sun] [Mg/Fe] Magnesium-to-iron abundance ratio (1)
12- 15 F4.2 [Sun] e_[Mg/Fe] 1σ error in [Mg/Fe] (1)
17 I1 --- NMg Number of lines used for Mg (2)
19- 22 F4.2 [Sun] [Si/Fe] Silicon-to-iron abundance ratio (3)
24- 27 F4.2 [Sun] e_[Si/Fe] 1σ error in [Si/Fe] (3)
29 I1 --- NSi Number of lines used for Si (4)
31- 35 F5.2 [Sun] [Ca/Fe] Calcium-to-iron abundance ratio (3)
37- 40 F4.2 [Sun] e_[Ca/Fe] ? 1σ error in [Ca/Fe] (3)
42 I1 --- NCa Number of lines used for Ca
44- 48 F5.2 [Sun] [Ti/Fe] Titanium-to-iron abundance ratio (3)
50- 53 F4.2 [Sun] e_[Ti/Fe] 1σ error in [Ti/Fe] (3)
55 I1 --- NTi Number of lines used for Ti
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Note (1): The stellar average is the result of fitting all three lines
simultaneously with synthesis. We have found a cluster average of
[Mg/H]=0.15±0.07, and [Mg/Fe]=0.11±0.05.
Note (2): We have measured three magnesium lines from the Gaia-ESO Survey (GES)
linelist at λ6318.72, 6319.24, and 6319.50Å. All Mg lines were
measured simultaneously via spectral synthesis.
Note (3): The final [X/Fe] value is the average of [X/Fe] values for all lines,
using each star's individual [Fe/H], and the given uncertainty is the
standard deviation of those values. We omit errors for stellar abundances
based on one line. We find (weighted) cluster averages [Si/H]=0.22±0.07,
[Si/Fe]=0.17±0.04, [Ca/H]=0.10±0.10, [Ca/Fe]=0.07±0.08,
[Ti/H]=0.03±0.12, [Ti/Fe]=-0.02±0.10.
Note (4): The Gaia-ESO Survey (GES) linelist has no SiI lines with reliable
log(gf) values in our wavelength range, so we have used the four lines from
the Arcturus-based linelist instead.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Star [2075/12550] Star number (G1)
7- 10 F4.2 [Sun] [Na/Fe] Sodium-to-iron abundance ratio
12- 15 F4.2 [Sun] e_[Na/Fe] ? 1σ error in [Na/Fe]
18 I1 --- NNa Number of lines used for Na
20- 24 F5.2 [Sun] [Ni/Fe] Nickel-to-iron abundance ratio
26- 29 F4.2 [Sun] e_[Ni/Fe] 1σ error in [Ni/Fe]
31 I1 --- NNi Number of lines used for Ni
33- 37 F5.2 [Sun] [Zr/Fe] Zirconium-to-iron abundance ratio
39- 42 F4.2 [Sun] e_[Zr/Fe] 1σ error in [Zr/Fe]
44 I1 --- NZr Number of lines used for Zr
46- 49 F4.2 [Sun] [Ba/Fe] Barium-to-iron abundance ratio
51- 54 F4.2 [Sun] e_[Ba/Fe] 1σ error in [Ba/Fe]
56- 60 F5.2 [Sun] [La/Fe] Lanthanum-to-iron abundance ratio
62- 65 F4.2 [Sun] e_[La/Fe] 1σ error in [La/Fe]
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Global notes:
Note (G1): From Gim et al. 1998 (cat. J/PASP/110/1318),
WEBDA (http://www.univie.ac.at/webda).
History:
* 09-Feb-2015: From electronic version of the journal
* 29-Mar-2016: Equinox corrected into B1950.0 in Table1 from
Erratum AJ, 149, 177
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 09-Feb-2015