J/ApJ/749/124 Spectroscopy on LMC clusters (Colucci+, 2012)
Comparison of convective overshooting models and their impact on abundances
from integrated light spectroscopy of young (<3Gyr) star clusters.
Colucci J.E., Bernstein R.A.
<Astrophys. J., 749, 124 (2012)>
=2012ApJ...749..124C 2012ApJ...749..124C
ADC_Keywords: Abundances ; Equivalent widths ; Magellanic Clouds ;
Clusters, globular ;
Keywords: galaxies: abundances - galaxies: individual: (LMC) -
galaxies: star clusters: general - stars: abundances -
globular clusters: individual (NGC1978, NGC1718, NGC1866, NGC1711,
NGC2100)
Abstract:
As part of an ongoing program to measure detailed chemical abundances
in nearby galaxies, we use a sample of young- to intermediate-age
clusters in the Large Magellanic Cloud with ages of 10Myr-2Gyr to
evaluate the effect of isochrone parameters, specifically core
convective overshooting, on Fe abundance results from high-resolution,
integrated light spectroscopy. In this work we also obtain fiducial Fe
abundances from high-resolution spectroscopy of the cluster individual
member stars. We compare the Fe abundance results for the individual
stars to the results from isochrones and integrated light spectroscopy
to determine whether isochrones with convective overshooting should be
used in our integrated light analysis of young- to intermediate-age
(10Myr-3Gyr) star clusters. We find that when using the isochrones
from the Teramo group, we obtain more accurate results for young- and
intermediate-age clusters over the entire age range when using
isochrones without convective overshooting. While convective
overshooting is not the only uncertain aspect of stellar evolution, it
is one of the most readily parameterized ingredients in stellar
evolution models, and thus important to evaluate for the specific
models used in our integrated light analysis. This work demonstrates
that our method for integrated light spectroscopy of star clusters can
provide unique tests for future constraints on stellar evolution
models of young- and intermediate-age clusters.
Description:
Our integrated light spectra of NGC 1978, NGC 1866, NGC 1711, and
NGC 2100 were obtained using the echelle spectrograph on the 2.5m du
Pont telescope at Las Campanas during the dark time in 2000 December
and 2001 January. The wavelength coverage is approximately 3700-7800Å.
The spectra of individual stars in the LMC clusters were obtained with
the MIKE double echelle spectrograph on the Magellan Clay Telescope
during three different observing runs in 2003 and 2004. We primarily
use lines with wavelengths between 4500 and 7500Å (red side only)
in our analysis, which is a region in common to all three runs.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 74 11 Stellar targets
table2.dat 93 171 Line parameters and stellar equivalent widths
table4.dat 73 11 Final Stellar Parameters and Fe Abundance Results
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See also:
J/ApJ/746/29 : High-resolution GC abundances. IV. 8 LMC GCs (Colucci+, 2012)
J/ApJ/735/55 : High-resolution GCs abundances. III. LMC (Colucci+, 2011)
J/ApJ/717/277 : Chemical composition of old LMC clusters (Mucciarelli+, 2010)
J/ApJ/695/L134 : Chemical anomalies in old LMC clusters (Mucciarelli+, 2009)
J/A+A/371/L5 : CCD Δa-photometry of NGC 1866 (Maitzen+, 2001)
J/AJ/119/1748 : WFPC 2 imaging of young LMC clusters (Keller+, 2000)
J/AJ/116/723 : LMC star clusters ages and metallicity (Bica+ 1998)
J/A+AS/112/367 : Selected Regions C and E in the LMC (Will+, 1995)
J/MNRAS/260/782 : CCD photometry of NGC 2004 and 2100 (Balona+ 1993)
J/ApJS/71/25 : NGC 1866 CCD photometry (Brocato+ 1989)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name Star name (NNNN-NNNN)
11- 18 F8.5 deg RAdeg [72/86] Right ascension (J2000) (1)
20- 28 F9.5 deg DEdeg [-70/-65] Declination (J2000) (1)
30- 37 A8 --- Date Run date
39- 43 I5 s Texp [2100/14800] Exposure time
45- 47 I3 pix-1 S/N [54/123] Signal-to-noise ratio at 6500Å
49- 57 A9 0.1nm lambda Wavelength range in angstroms
59- 63 F5.2 mag Vmag [13/17.1] V-band magnitude (1)
65- 69 F5.2 mag (m-M)0 [18.4/18.5] Distance modulus (2)
71- 74 F4.2 mag E(B-V) [0.06/0.3] Color excess (2)
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Note (1): Coordinates and magnitudes for each cluster were taken from these
catalogs:
NGC 1978 = Will et al. (1995, Cat. J/A+AS/112/367;
<Cl* NGC 1978 WBT NNNN> in Simbad),
NGC 1866 = Brocato et al. (1989, Cat. J/ApJS/71/25;
<Cl* NGC 1866 BBC NNNN> in Simbad)
NGC 1711 = Sagar et al. (1991A&AS...90..387S 1991A&AS...90..387S;
<Cl* NGC 1711 SRD NNNN> in Simbad)
NGC 2100 = Robertson, J.W. (1974A&AS...15..261R 1974A&AS...15..261R;
<Cl* NGC 2100 Rob ANNN> in Simbad).
Note (2): Adopted distance moduli and reddening values for the clusters
were taken from:
NGC 1978 = Ferraro et al. (2006ApJ...645L..33F 2006ApJ...645L..33F),
NGC 1866 = Mucciarelli et al. (2011MNRAS.413..837M 2011MNRAS.413..837M),
NGC 1711 = Dirsch et al. (2000A&A...360..133D 2000A&A...360..133D),
NGC 2100 = Keller et al. (2000, Cat. J/AJ/119/1748).
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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 A5 --- Ion Species identification, FeI or FeII (1)
7- 14 F8.3 0.1nm lambda [4508/7942] Wavelength; in Angstroms (1)
16- 20 F5.3 eV ExPot [0/5.6] Excitation Potential (1)
22- 27 F6.3 [-] log(gf) [-6.4/0.7] log oscillator strength (2)
29- 33 F5.1 0.1pm EW1978-737 ? Equivalent width in 1978-737 (3)
35- 39 F5.1 0.1pm EW1978-730 ? Equivalent width in 1978-730 (3)
41- 45 F5.1 0.1pm EW1866-954 ? Equivalent width in 1866-954 (3)
47- 51 F5.1 0.1pm EW1866-1653 ? Equivalent width in 1866-1653 (3)
53- 57 F5.1 0.1pm EW1866-1667 ? Equivalent width in 1866-1667 (3)
59- 63 F5.1 0.1pm EW1711-831 ? Equivalent width in 1711-831 (3)
65- 69 F5.1 0.1pm EW1711-988 ? Equivalent width in 1711-988 (3)
71- 75 F5.1 0.1pm EW1711-1194 ? Equivalent width in 1711-1194 (3)
77- 81 F5.1 0.1pm EW2100-c2 ? Equivalent width in 2100-c2 (3)
83- 87 F5.1 0.1pm EW2100-c12 ? Equivalent width in 2100-c12 (3)
89- 93 F5.1 0.1pm EW2100-b22 ? Equivalent width in 2100-b22 (3)
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Note (1): Lines listed twice correspond to those measured in adjacent
orders with overlapping wavelength coverage.
Note (2): Taken from Colucci et al. (2011, Cat. J/ApJ/735/55) and
references therein.
Note (3): In units of milli-Angstroms.
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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- 9 A9 --- Name Star designation (NNNN-NNNN)
11- 15 F5.2 --- VMag [-6.2/-1.6] Absolute V-band magnitude (3)
17- 20 F4.2 --- B-V [0.5/1.7] B-V color index (3)
22- 25 I4 K Teff [3885/5850] Effective temperature
27- 30 F4.2 [cm/s2] logg [0.05/2] Surface gravity
32- 35 F4.2 km/s Vt [1.3/3.3] Microturbulent velocity
37- 41 F5.2 [Sun] [Fe/H]1 [-0.7/-0.03] FeI abundance
43- 46 F4.2 [Sun] e_[Fe/H]1 [0.1/0.3] [Fe/H]1 uncertainty (4)
48- 49 I2 --- N1 [17/93] Number of FeI lines used
51- 55 F5.2 [Sun] [Fe/H]2 [-0.7/-0.07] FeII abundance
57- 60 F4.2 [Sun] e_[Fe/H]2 [0.1/0.5] [Fe/H]2 uncertainty (4)
62- 63 I2 --- N2 [3/26] Number of FeII lines used
65- 69 F5.1 km/s RV [241/303] Stellar radial velocity
71- 73 F3.1 km/s e_RV [0.1/0.3] RV uncertainty
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Note (3): V magnitudes and B-V colors have been distance and reddening
corrected with the (m-M) and E(B-V) values in Table 1.
Note (4): The quoted uncertainty for FeI and FeII abundances is the
standard deviation in the abundance of all of the measured lines of
each species, σFe.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 27-Nov-2013