J/ApJ/735/55 High-resolution GCs abundances. III. LMC (Colucci+, 2011)
Globular cluster abundances from high-resolution, integrated-light spectroscopy.
III. The Large Magellanic Cloud: Fe and ages.
Colucci J.E., Bernstein R.A., Cameron S.A., McWilliam A.
<Astrophys. J., 735, 55 (2011)>
=2011ApJ...735...55C 2011ApJ...735...55C
ADC_Keywords: Abundances ; Clusters, globular ; Magellanic Clouds ;
Equivalent widths
Keywords: galaxies: abundances - galaxies: individual (LMC) -
galaxies: star clusters: general - globular clusters: individual -
(NGC 2005, NGC 2019, NGC 1916, NGC 1978, NGC 1718, NGC 1866, -
NGC 1711, NGC 2100) - stars: abundances
Abstract:
In this paper, we refine our method for the abundance analysis of
high-resolution spectroscopy of the integrated light of unresolved
globular clusters (GCs). This method was previously demonstrated for
the analysis of old (>10Gyr) Milky Way (MW) GCs. Here, we extend the
technique to young clusters using a training set of nine GCs in the
Large Magellanic Cloud. Depending on the signal-to-noise ratio of the
data, we use 20-100 Fe lines per cluster to successfully constrain the
ages of old clusters to within a ∼5Gyr range, the ages of ∼2Gyr
clusters to a 1-2Gyr range, and the ages of the youngest clusters
(0.05-1Gyr) to a ∼200Myr range. We also demonstrate that we can
measure [Fe/H] in clusters with any age less than 12Gyr with similar
or only slightly larger uncertainties (0.1-0.25dex) than those
obtained for old MW GCs (0.1dex); the slightly larger uncertainties
are due to the rapid evolution in stellar populations at these ages.
In this paper, we present only Fe abundances and ages. For several of
the clusters in this sample, there are no high-resolution abundances
in the literature from individual member stars; our results are the
first detailed chemical abundances available.
Description:
All of the data for the LMC training set clusters, with the exception
of NGC 1718, were obtained using the echelle spectrograph on the 2.5m
du Pont telescope at Las Campanas during dark time in 2000 December
and 2001 January. The wavelength coverage of these spectra is
approximately 3700-7800Å. NGC 1718 was observed with the MIKE
double echelle spectrograph on the 6.5m Magellan Clay telescope in
2006 November.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 86 11 LMC cluster sample (9 GCs)
ew.dat 37 1521 Line parameters and integrated light equivalent
widths for 9 LMC GCs
--------------------------------------------------------------------------------
See also:
J/ApJ/717/277 : Chemical composition of LMC clusters (Mucciarelli+, 2010)
J/ApJ/695/L134 : Chemical anomalies in old LMC clusters (Mucciarelli+, 2009)
J/ApJ/704/385 : M31 integrated light abundances (Colucci+, 2009)
J/AJ/136/375 : Chemical composition of LMC red giants (Mucciarelli+, 2008)
J/MNRAS/386/1380 : BVRI photometry of LMC star clusters (Kumar+, 2008)
J/AJ/132/1630 : CaII spectroscopy in Magellanic Cloud clusters (Grocholski+,
2006)
J/MNRAS/300/665 : HST Photometry of LMC Old Globular Clusters (Olsen+, 1998)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- Cage Age classification (>5Gyr: old,
1-3Gyr: intermediate or <1Gyr: young)
5- 7 A3 --- --- [NGC]
9- 12 I4 --- NGC Globular cluster NGC number
14 I1 h RAh Hour of right ascension (J2000)
16- 17 I2 min RAm Minute of right ascension (J2000)
19- 22 F4.1 s RAs Second of right ascension (J2000)
24 A1 --- DE- Sign of declination (J2000)
25- 26 I2 deg DEd Degree of declination (J2000)
28- 29 I2 arcmin DEm Arcminute of declination (J2000)
31- 32 I2 arcsec DEs Arcsecond of declination (J2000)
34- 38 F5.2 mag Vmag V-band magnitude (1)
40- 43 F4.2 mag B-V B-V color index
45- 48 F4.2 mag e_B-V ? B-V uncertainty
50- 53 F4.2 mag E(B-V) ? B-V color excess
55- 58 F4.2 mag e_E(B-V) ? E(B-V) uncertainty
60 A1 --- l_Age Limit flag on Age
61- 66 F6.3 Gyr Age Age
68- 72 F5.2 [-] [Fe/H] Fe/H abundance
74- 78 F5.2 [-] [a/fe] ? α/Fe abundance (2)
80- 86 A7 --- Ref Reference(s) (3)
--------------------------------------------------------------------------------
Note (1): From Pessev et al. (2008MNRAS.385.1535P 2008MNRAS.385.1535P) and Bica et al.
(1996ApJS..102...57B 1996ApJS..102...57B).
Note (2): Mean of [Si/Fe], [Ca/Fe], and [Ti/Fe] abundances from Johnson et al.
2006ApJ...640..801J 2006ApJ...640..801J, Mucciarelli et al. 2008, Cat. J/AJ/136/375,
Jasniewicz & Thevenin 1994A&A...282..717J 1994A&A...282..717J, and Mucciarelli et al.
2010, Cat. J/ApJ/717/277 and mean of [O/Fe] from Hill et al.
2000A&A...364L..19H 2000A&A...364L..19H.
Note (3): References for B-V, E(B-V), Age and [Fe/H] as follows:
1 = Olszewski et al. 1991AJ....101..515O 1991AJ....101..515O;
2 = Johnson et al. 2006ApJ...640..801J 2006ApJ...640..801J;
3 = Mucciarelli et al. 2008, Cat. J/AJ/136/375;
4 = Hill et al. 2000A&A...364L..19H 2000A&A...364L..19H;
5 = Grocholski et al. 2006, Cat. J/AJ/132/1630;
6 = Kerber et al. 2007A&A...462..139K 2007A&A...462..139K;
7 = Mucciarelli et al. 2007AJ....133.2053M 2007AJ....133.2053M;
8 = Dirsch et al. 2000A&A...360..133D 2000A&A...360..133D;
9 = Jasniewicz & Thevenin 1994A&A...282..717J 1994A&A...282..717J;
10 = Elson 1991ApJS...76..185E 1991ApJS...76..185E;
11 = Kumar et al. 2008, Cat. J/MNRAS/386/1380;
12 = Wolf et al. 2007ApJ...655..179W 2007ApJ...655..179W;
13 = Pessev et al. 2008MNRAS.385.1535P 2008MNRAS.385.1535P;
14 = Olsen et al. 1998, Cat. J/MNRAS/300/665;
15 = Walker et al. 2001ApJ...560L.139W 2001ApJ...560L.139W;
16 = Mucciarelli et al. 2010, Cat. J/ApJ/717/277
--------------------------------------------------------------------------------
Byte-by-byte Description of file: ew.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- NGC LMC GC number
6- 9 A4 --- Ion [Fe I] Species identification (FeI only)
11- 18 F8.3 0.1nm lambda Wavelength in Angstroms
20- 24 F5.3 eV ExPot Excitation potential
26- 31 F6.3 [-] log(gf) Log of the oscillator strength
33- 37 F5.1 10-13m EW ? Equivalent width in units of milli-Angstroms
--------------------------------------------------------------------------------
History:
From electronic version of the journal
References:
McWilliam & Bernstein. Paper I. 2008ApJ...684..326M 2008ApJ...684..326M
Colucci et al. Paper II. 2009ApJ...704..385C 2009ApJ...704..385C Cat. J/ApJ/704/385
Colucci et al. Paper IV. 2012ApJ...746...29C 2012ApJ...746...29C
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 30-Nov-2012