J/ApJ/708/1335 Spectroscopy of globulars in NGC 5128 (Woodley+, 2010)
The ages, metallicities, and alpha element enhancements of globular clusters in
the elliptical NGC 5128: a homogeneous spectroscopic study with Gemini/Gemini
multi-object spectrograph.
Woodley K.A., Harris W.E., Puzia T.H., Gomez M., Harris G.L.H., Geisler D.
<Astrophys. J., 708, 1335-1356 (2010)>
=2010ApJ...708.1335W 2010ApJ...708.1335W
ADC_Keywords: Abundances ; Clusters, globular ; Galaxies, nearby ;
Radial velocities ; Spectroscopy
Keywords: galaxies: elliptical and lenticular, cD - galaxies: evolution -
galaxies: individual (NGC 5128) - galaxies: star clusters -
globular clusters: general
Abstract:
We present new integrated light spectroscopy of globular clusters
(GCs) in NGC 5128, a nearby giant elliptical galaxy less than 4Mpc
away, in order to measure radial velocities and derive ages,
metallicities, and alpha-element abundance ratios. Using the Gemini
South 8 meter telescope with the instrument Gemini Multi-Object
Spectrograph, we obtained spectroscopy in the range of ∼3400-5700Å
for 72 GCs with a signal-to-noise ratio greater than 30Å-1; and
we have also discovered 35 new GCs within NGC 5128 from our radial
velocity measurements. We measured and compared the Lick indices from
HδA through Fe5406 with the single stellar population models
of Thomas et al. (2003MNRAS.339..897T 2003MNRAS.339..897T, 2004MNRAS.351L..19T 2004MNRAS.351L..19T) in order
to derive age, metallicity, and [α/Fe] values.
Description:
We obtained low-resolution spectroscopy of known and candidate GCs
with the Gemini South 8 meter telescope using the Gemini Multi-Object
Spectrograph (GMOS). We placed eight fields around the center of NGC
5128, covering the inner 15kpc of the halo over two observing periods
in 2005 and 2007, program IDs GS-2005A-Q-28 (PI: William E. Harris)
and GS-2007A-Q-55 (PI: Doug Geisler).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 67 114 New radial velocity measurements of known
Globular Clusters
table3.dat 79 37 Radial velocity measurements of new Globular
Clusters
table4.dat 307 136 Lick indices and uncertainties for Globular
Clusters in NGC 5128
table5.dat 52 72 Ages, metallicities, and [α/Fe] of
Globular Clusters in NGC 5128
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See also:
J/AJ/140/2101 : NGC 5128 globular clusters photometry (Sinnott+, 2010)
J/AJ/139/1871 : Kinematics of GCs in NGC 5128 (Woodley+, 2010)
J/MNRAS/386/1443 : 2dF study of globular clusters in NGC 5128 (Beasley+, 2008)
J/AJ/134/494 : NGC 5128 GCs UBVRICMT1 phot. + RV (Woodley+, 2007)
J/AJ/128/712 : Washington Photometry in NGC 5128 (Harris+, 2004)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- --- [GC]
3- 6 I04 --- GC Globular Cluster number,
<[WHB2007] NNN> in Simbad
8- 18 A11 --- OName Old Globular Cluster name
20 A1 --- n_OName [b] GC from Woodley et al. 2010
(Cat. J/AJ/139/1871)
22- 23 I2 h RAh Hour of right ascension (J2000)
25- 26 I2 min RAm Minute of right ascension (J2000)
28- 32 F5.2 s RAs Second of right ascension (J2000)
34 A1 --- DE- Sign of declination (J2000)
35- 36 I2 deg DEd Degree of declination (J2000)
38- 39 I2 arcmin DEm Arcminute of declination (J2000)
41- 44 F4.1 arcsec DEs Arcsecond of declination (J2000)
46 I1 --- Mask Mask/field number
48- 49 I2 --- Slit Slit number
51- 53 I3 0.1nm-1 S/N Approximate S/N measured per Å between
4700Å and 4830Å
55- 57 I3 km/s VGMOS GMOS radial velocity
59- 60 I2 km/s e_VGMOS VGMOS uncertainty
62- 64 I3 km/s RV ? Weighted mean radial velocity (2)
66- 67 I2 km/s e_RV ? RV uncertainty
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Note (2): Weighted mean of all previously published radial velocity measurements
for that GC including the radial velocity determined in this study.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 A2 --- --- [GC]
3- 6 I04 --- GC Globular Cluster number,
<[WHB2007] NNN> in Simbad
8- 9 I2 h RAh Hour of right ascension (J2000)
11- 12 I2 min RAm Minute of right ascension (J2000)
14- 18 F5.2 s RAs Second of right ascension (J2000)
20 A1 --- DE- Sign of declination (J2000)
21- 22 I2 deg DEd Degree of declination (J2000)
24- 25 I2 arcmin DEm Arcminute of declination (J2000)
27- 30 F4.1 arcsec DEs Arcsecond of declination (J2000)
32 I1 --- Mask Mask/field number
34- 35 I2 --- Slit Slit number
37- 38 I2 0.1nm-1 S/N Approximate S/N measured per Å between
4700Å and 4830Å (470-483nm)
40- 42 I3 km/s VGMOS ? GMOS radial velocity
44- 45 I2 km/s e_VGMOS ? VGMOS uncertainty
46 A1 --- n_VGMOS [bc] averaged GMOS velocity (1)
48- 52 F5.2 mag Cmag ? Washington C band magnitude (2)
54- 57 F4.2 mag e_Cmag ? Cmag uncertainty
59- 63 F5.2 mag Mmag ? Washington M band magnitude (2)
65- 68 F4.2 mag e_Mmag ? Mmag uncertainty
70- 74 F5.2 mag T1mag ? Washington T1 band magnitude (2)
76- 79 F4.2 mag e_T1mag ? T1mag uncertainty
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Note (1): Flag as follows:
b = The quoted radial velocity is a weighted average. The individual
measurements were 655±69 for m=2, s=10 and 687±52 for m=7 and s=07.
c = The quoted radial velocity is a weighted average. The individual
measurements were 410±46 for m=7, s=05 and 398±34 for m=6 and s=22.
Note (2): C, M, and T1 Washington photometry with associated uncertainties
from Harris et al. (2004, Cat. J/AJ/128/712).
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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- 2 A2 --- --- [GC]
3- 6 I04 --- GC Globular Cluster number,
<[WHB2007] NNN> in Simbad
8- 14 F7.4 0.1nm HdA Lick HδA index (in Angstroems)
16- 22 F7.4 0.1nm HdF Lick HδF index (in Angstroems)
24- 30 F7.4 mag CN1 Lick CN1 index
32- 38 F7.4 mag CN2 Lick CN2 index
40- 46 F7.4 0.1nm Ca4227 Lick Ca4227 index (in Angstroems)
48- 55 F8.4 0.1nm G4300 Lick G4300 index (in Angstroems)
57- 64 F8.4 0.1nm HgA Lick HγA index (in Angstroems)
66- 72 F7.4 0.1nm HgF Lick HγF index (in Angstroems)
74- 80 F7.4 0.1nm Fe4383 Lick Fe4383 index (in Angstroems)
82- 88 F7.4 0.1nm Ca4455 Lick Ca4455 index (in Angstroems)
90- 96 F7.4 0.1nm Fe4531 Lick Fe4531 index (in Angstroems)
98-104 F7.4 0.1nm C24668 Lick C24668 index (in Angstroems)
106-111 F6.4 0.1nm Hb Lick Hβ index (in Angstroems)
113-119 F7.4 0.1nm Fe5015 Lick Fe5015 index (in Angstroems)
121-127 F7.4 mag Mg1 ? Lick Mg1 index
129-135 F7.4 mag Mg2 ? Lick Mg2 index
137-143 F7.4 0.1nm Mgb ? Lick Mgb index (in Angstroems)
145-151 F7.4 0.1nm Fe5270 ? Lick Fe5270 index (in Angstroems)
153-159 F7.4 0.1nm Fe5335 ? Lick Fe5335 index (in Angstroems)
161-167 F7.4 0.1nm Fe5406 ? Lick Fe5406 index (in Angstroems)
169-174 F6.4 0.1nm e_HdA Uncertainty in HdA (in Angstroems)
176-181 F6.4 0.1nm e_HdF Uncertainty in HdF (in Angstroems)
183-188 F6.4 mag e_CN1 Uncertainty in CN1
190-195 F6.4 mag e_CN2 Uncertainty in CN2
197-202 F6.4 0.1nm e_Ca4227 Uncertainty in Ca4227 (in Angstroems)
204-209 F6.4 0.1nm e_G4300 Uncertainty in G4300 (in Angstroems)
211-216 F6.4 0.1nm e_HgA Uncertainty in HgA (in Angstroems)
218-223 F6.4 0.1nm e_HgF Uncertainty in HgF (in Angstroems)
225-230 F6.4 0.1nm e_Fe4383 Uncertainty in Fe4383 (in Angstroems)
232-237 F6.4 0.1nm e_Ca4455 Uncertainty in Ca4455 (in Angstroems)
239-244 F6.4 0.1nm e_Fe4531 Uncertainty in Fe4531 (in Angstroems)
246-251 F6.4 0.1nm e_C24668 Uncertainty in C24668 (in Angstroems)
253-258 F6.4 0.1nm e_Hb Uncertainty in Hb (in Angstroems)
260-265 F6.4 0.1nm e_Fe5015 Uncertainty in Fe5015 (in Angstroems)
267-272 F6.4 mag e_Mg1 ? Uncertainty in Mg1
274-279 F6.4 mag e_Mg2 ? Uncertainty in Mg2
281-286 F6.4 0.1nm e_Mgb ? Uncertainty in Mgb (in Angstroems)
288-293 F6.4 0.1nm e_Fe5270 ? Uncertainty in Fe5270 (in Angstroems)
295-300 F6.4 0.1nm e_Fe5335 ? Uncertainty in Fe5335 (in Angstroems)
302-307 F6.4 0.1nm e_Fe5406 ? Uncertainty in Fe5406 (in Angstroems)
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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- 2 A2 --- --- [GC]
3- 6 I04 --- GC Globular Cluster number,
<[WHB2007] NNN> in Simbad
7 A1 --- f_GC [abcd] Discordant values (1)
9- 12 F4.1 Gyr Age Estimated age
14- 16 F3.1 Gyr E_Age Positive error on Age
18- 20 F3.1 Gyr e_Age Negative error on Age
22- 26 F5.2 [-] [Z/H] The [Z/H] metallicity
28- 31 F4.2 [-] E_[Z/H] Positive error on [Z/H]
33- 36 F4.2 [-] e_[Z/H] Negative error on [Z/H]
38- 42 F5.2 [-] [a/H] The [α/H] abundance ratio
44- 47 F4.2 [-] E_[a/H] Positive error on [a/H]
49- 52 F4.2 [-] e_[a/H] Negative error on [a/H]
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Note (1): Discordance flag indicates a second spectrum with lower S/N:
a = age=9.2±0.1Gyr, [Z/H]=-1.51±0.01, [α/Fe]=-0.23±0.06
b = age=8.8+0.1-0.9Gyr, [Z/H]=-0.78+0.03-0.01, [α/Fe]=+0.11+0.02-0.03
c = age=8.2+1.1-0.2Gyr, [Z/H]=-1.43+0.03-0.02, [α/Fe]=-0.62+0.05-0.05
d = age=9.3+3.9-4.8Gyr, [Z/H]=-1.08+0.92-0.09, [α/Fe]=-0.50+0.06-0.07
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 13-Jul-2011