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
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:
FileName Lrecl Records Explanations
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
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
Bytes Format Units Label Explanations
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)
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; <Cl* NGC 1711 SRD NNNN> in Simbad) NGC 2100 = Robertson, J.W. (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), NGC 1866 = Mucciarelli et al. (2011MNRAS.413..837M), NGC 1711 = Dirsch et al. (2000A&A...360..133D), NGC 2100 = Keller et al. (2000, Cat. J/AJ/119/1748).
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
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)
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.
Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
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
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.
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 27-Nov-2013
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