J/ApJ/773/L36 NGC 5128 globular cluster abundances (Colucci+, 2013)
Chemical abundance evidence of enduring high star formation rates in an
early-type galaxy: high [Ca/Fe] in NGC 5128 globular clusters.
Colucci J.E., Duran M.F., Bernstein R.A., McWilliam A.
<Astrophys. J., 773, L36 (2013)>
=2013ApJ...773L..36C 2013ApJ...773L..36C
ADC_Keywords: Abundances ; Clusters, globular ; Galaxies, nearby ;
Radial velocities ; Velocity dispersion ; Spectroscopy
Keywords: galaxies: abundances; galaxies: elliptical and lenticular, cD;
galaxies: individual: NGC 5128; galaxies: star clusters: general;
galaxies: stellar content
Abstract:
We present [Fe/H], ages, and Ca abundances for an initial sample of 10
globular clusters in NGC 5128 obtained from high-resolution, high
signal-to-noise ratio echelle spectra of their integrated light. All
abundances and ages are obtained using our original technique for
high-resolution integrated light abundance analysis of globular
clusters. The clusters have a range in [Fe/H] between -1.6 and -0.2.
In this sample, the average [Ca/Fe] for clusters with [Fe/H]←0.4 is
+0.37±0.07, while the average [Ca/Fe] in our Milky Way (MW) and M31
GC samples is +0.29±0.09 and +0.24±0.10, respectively. This may
imply a more rapid chemical enrichment history for NGC 5128 than for
either the MW or M31. This sample provides the first quantitative
picture of the chemical history of NGC 5128 that is directly
comparable to what is available for the MW. Data presented here were
obtained with the MIKE echelle spectrograph on the Magellan Clay
Telescope.
Description:
We obtained our spectra using the MIKE spectrograph on the 6.5m
Magellan Clay Telescope. The data were taken over six observing runs
from 2004 to 2012. All data were taken with an instrumental resolution
of 28000 for the blue arm (∼335-505nm) and 22000 for the red arm
(∼480-900nm).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 101 11 Observations and globular cluster (GC) properties
from the literature
table2.dat 76 101 Line parameters and GC integrated light (IL)
abundances
table3.dat 78 10 NGC 5128 GC ages and abundances
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See also:
J/AJ/143/84 : New candidate globular clusters in NGC 5128 (Harris+, 2012)
J/ApJ/708/1335 : Spectroscopy of globulars in NGC 5128 (Woodley+, 2010)
J/AJ/140/2101 : NGC 5128 globular clusters photometry (Sinnott+, 2010)
J/AJ/139/1871 : Kinematics of globulars in NGC 5128 (Woodley+, 2010)
J/ApJ/705/1533 : NGC 5128 globular clusters (Chattopadhyay+, 2009)
J/ApJ/704/385 : M31 integrated light abundances (Colucci+, 2009)
J/MNRAS/386/1443 : 2dF study of globular clusters in NGC 5128 (Beasley+, 2008)
J/ApJ/682/199 : Globulars with X-ray sources in NGC 5128 (Woodley+, 2008)
J/AJ/134/494 : NGC 5128 GCs UBVRICMT1 phot. + RV (Woodley+, 2007)
J/AJ/132/2187 : MCT1 photometry of NGC 5128 globular clusters (Harris+, 2006)
J/AJ/130/2140 : Abundances and velocities in globular clusters (Pritzl+, 2005)
J/ApJS/150/367 : Globular clusters in NGC 5128 (Peng+, 2004)
J/A+A/369/812 : UVKs phot. of globular clusters in NGC 5128 (Rejkuba, 2001)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- P04 Name from Peng et al. 2004 (1)
11- 13 A3 --- --- [GC0]
14- 16 I03 --- GC Globular cluster ID in Woodley et al. 2007 (G1)
18- 19 I2 h RAh Hour of right ascension (J2000)
21- 22 I2 min RAm Minute of right ascension (J2000)
24- 27 F4.1 s RAs Second of right ascension (J2000)
29 A1 --- DE- Sign of declination (J2000)
30- 31 I2 deg DEd Degree of declination (J2000)
33- 34 I2 arcmin DEm Arcminute of declination (J2000)
36- 39 F4.1 arcsec DEs Arcsecond of declination (J2000)
41- 45 F5.2 mag Vmag [17.1/18.7]? V-band magnitude from P04 (1)
47- 50 F4.1 kpc Rgc [3.6/23.1]? Projected galactocentric radius
from NGC 5128 (G1)
52- 56 F5.2 --- [M/H] [-1.6/-0.2]? [M/H] metallicity value of
Beasley et al. 2008 (J/MNRAS/386/1443)
58- 62 F5.2 --- [Z/H] [-0.7/1]? [Z/H] metallicity value by W10 (2)
64- 68 F5.2 --- [a/Fe] [-0.1/0.3]? [α/Fe] metallicity value
by W10 (2)
70- 72 I3 km/s Vr [363/782]? Radial velocity from W07 (G1)
74- 75 I2 km/s e_Vr [1/34]? Vr uncertainty
77- 80 F4.1 km/s Vs [13/24]? Line-of-sight velocity dispersion
(vσ) measured by Taylor et al.
(2010ApJ...712.1191T 2010ApJ...712.1191T)
82- 84 F3.1 km/s e_Vs [1/3]? Vs uncertainty
86- 93 A8 "YYYY/MMM" Date Month and year of the multi-night observing run
95- 98 F4.1 h Exp [5/16.6]? Exposure time
100-101 I2 --- S/N [38/81]? 604nm signal to noise ratio
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Note (1): Names, coordinates, and V magnitudes are taken from Peng et al.
(P04; 2004, J/ApJS/150/367).
Note (2): W10 = Woodley et al. (2010, J/ApJ/708/1335;
<[WHB2007] GCNNNN> in Simbad)
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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- 4 A4 --- Ion Species identifier (CaI or FeI)
6- 13 F8.3 0.1nm lambda [4369.7/7531.2] Wavelength; in Angstroms
15- 19 F5.3 eV ExPot [0/4.8] Excitation potential
21- 26 F6.3 [-] log(gf) [-4.9/0.7] Log of the oscillator strength
28- 31 F4.2 [-] GC0040 ? Abundance (logε) in GC0040
33- 36 F4.2 [-] GC0041 ? Abundance (logε) in GC0041
38- 41 F4.2 [-] GC0086 ? Abundance (logε) in GC0086
43- 46 F4.2 [-] GC0106 ? Abundance (logε) in GC0106
48- 51 F4.2 [-] GC0124 ? Abundance (logε) in GC0124
53- 56 F4.2 [-] GC0227 ? Abundance (logε) in GC0227
58- 61 F4.2 [-] GC0265 ? Abundance (logε) in GC0265
63- 66 F4.2 [-] GC0277 ? Abundance (logε) in GC0277
68- 71 F4.2 [-] GC0282 ? Abundance (logε) in GC0282
73- 76 F4.2 [-] GC0365 ? Abundance (logε) in GC0365
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- --- [GC0]
4- 6 I03 --- GC Globular cluster ID in Woodley et al. 2007 (G1)
8- 9 I2 Gyr Age1 Lower range of age
10 A1 --- --- [-]
11- 12 I2 Gyr Age2 Upper range of age
14- 18 F5.2 [Sun] [Fe/H] [-1.7/-0.2] Metallicity
20- 21 I2 --- NFe [16/37] Number of FeI lines analyzed
23- 26 F4.2 --- sigN [0.04/0.3] Standard deviation of the mean
abundance (σN)
28- 31 F4.2 [Sun] sigFe [0.03/0.2] Error in the mean abundance (3)
33- 36 F4.2 --- sigAge [0.02/0.1] Systematic age uncertainty
σAge in quadrature
38- 41 F4.2 --- sigT [0.04/0.2] Total uncertainty on the [Fe/H] (3)
43 A1 --- Atm [A/S] Kurucz α-enhanced (A) or
scaled-solar atmosphere (S) (4)
45- 49 F5.2 [Sun] [Ca/Fe] [0.03/0.5] [Ca/Fe] abundance
51- 52 I2 --- NCa [3/11] Number of CaI lines analyzed
54- 57 F4.2 [Sun] sigCa [0.05/0.2] Error in the mean measured CaI
abundance
59- 62 F4.1 km/s Vsig [10/21] Line-of-sight velocity dispersion of
the GC (Vσ) (5)
64- 67 F4.2 km/s e_Vsig [0.2/1.3] Vsig uncertainty
69- 73 F5.1 km/s HRV [363/784] Heliocentric corrected radial velocity
75- 78 F4.2 km/s e_HRV [0.2/1.6] HRV uncertainty
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Note (3): The total uncertainty on the [Fe/H] is defined as
σT=(σ2+σ2Age)0.5, where
σ=σN/(NFe-1)0.5 is the error in the mean abundance
and NFe is the number of FeI lines analyzed in each GC.
Note (4): "A" or "S" designates whether Kurucz α-enhanced or
scaled-solar atmospheres were used, respectively. This decision is
based explicitly on the [Ca/Fe] abundances measured for each GC; a
proxy for [α/Fe].
Note (5): Vσ is the line-of-sight velocity dispersion of the GC
measured by fxcor, and used to convolve with synthesized spectra.
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Blobal Notes:
Note (G1): Names, projected galactocentric radii from NGC 5128, and radial
velocities (vr) are from Woodley et al. 2007 (W07 = J/AJ/134/494;
<[WHB2007] GCNNNN> in Simbad). Note that the vr from W07 are
averages from a compilation of velocity measurements from spectra of
different resolution and S/N. Rgc were calculated assuming a distance
to NGC 5128 of 3.8Mpc (Harris et al. 2010PASA...27..457H 2010PASA...27..457H).
History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 24-Feb-2015