J/MNRAS/372/1259 Abundances of extragalactic globular clusters (Sharina+, 2006)
Ages, metallicities and [α/Fe] ratios of globular clusters in
NGC 147, 185 and 205.
Sharina M.E., Afanasiev V.L., Puzia T.H.
<Mon. Not. R. Astron. Soc., 372, 1259-1274 (2006)>
=2006MNRAS.372.1259S 2006MNRAS.372.1259S
ADC_Keywords: Galaxies, nearby ; Clusters, globular ; Abundances
Keywords: globular clusters: general - galaxies: abundances -
galaxies: individual: NGC 147 - galaxies: individual: NGC 185 -
galaxies: individual: NGC 205 - galaxies: star clusters
Abstract:
We present measurements of ages, metallicities and [alpha/Fe] ratios
for 16 globular clusters (GCs) in NGC 147, 185 and 205 and of the
central regions of the diffuse galaxy light in NGC 185 and 205. Our
results are based on spectra obtained with the SCORPIO multislit
spectrograph at the 6-m telescope of the Russian Academy of Sciences.
We include in our analysis high-quality Hubble Space Telescope/WFPC2
photometry of individual stars in the studied GCs to investigate the
influence of their horizontal branch (HB) morphology on the
spectroscopic analysis. All our sample GCs appear to be old (T>8Gyr)
and metal-poor ([Z/H]<1.1), except for the GCs Hubble V in NGC 205
(T=1.2±0.6Gyr, [Z/H]=0.6±0.2), Hubble VI in NGC 205 (T=4±2Gyr,
[Z/H]=0.8±0.2) and FJJVII in NGC 185 (T=7±3Gyr, [Z/H]=0.8±0.2).
The majority of our GCs sample has solar [alpha/Fe] enhancement in
contrast to the halo population of GCs in M31 and the Milky Way. The
HB morphologies for our sample GCs follow the same behaviour with
metallicity as younger halo Galactic GCs. We show that it is unlikely
that they bias our spectroscopic age estimates based on Balmer
absorption-line indices. Spectroscopic ages and metallicities of the
central regions in NGC 205 and 185 coincide with those obtained from
colour-magnitude diagrams. The central field stellar populations in
these galaxies have approximately the same age as their most central
GCs (Hubble V in NGC 205 and FJJIII in NGC 185), but are more
metal-rich than the central GCs.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
objects.dat 60 16 Globular cluster positions
table5.dat 119 27 GC indices (lambda<4700Å) corrected for zero-points
of transformation to the standard system
table6.dat 119 27 GC indices (lambda>4700Å) corrected for zero-points
of transformation to the standard system
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Byte-by-byte Description of file: objects.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Galaxy Galaxy name
9- 19 A11 --- GC Globular cluster name
21- 22 I2 h RAh Right ascension (J2000)
24- 25 I2 min RAm Right ascension (J2000)
27- 31 F5.2 s RAs Right ascension (J2000)
33 A1 --- DE- Declination sign (J2000)
34- 35 I2 deg DEd Declination (J2000)
37- 38 I2 arcmin DEm Declination (J2000)
40- 43 F4.1 arcsec DEs Declination (J2000)
46- 60 A15 --- SName Simbad name of the globular cluster
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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- 32 A32 --- ID Globular cluster or Group name
33- 35 I3 --- S/N Signal-to-noise ratio (1)
37- 41 F5.2 0.1nm Ca4227 ?=- Ca4227 spectral index
43- 46 F4.2 0.1nm G4300 ?=- G4300 spectral index
48- 52 F5.2 0.1nm HgA ?=- HγA spectral index
54- 57 F4.2 0.1nm HgF ?=- HγF spectral index
59- 62 F4.2 0.1nm Fe4383 ?=- Fe4383 spectral index
64- 67 F4.2 0.1nm Ca4455 ?=- Ca4455 spectral index
69- 73 F5.2 0.1nm Fe4531 ?=- Fe4531 spectral index
75- 79 F5.2 0.1nm Fe4668 ?=- Fe4668 spectral index
81- 84 F4.2 0.1nm e_Ca4227 ?=- rms uncertainty on Ca4227 (G1)
86- 89 F4.2 0.1nm e_G4300 ?=- rms uncertainty on G4300 (G1)
91- 94 F4.2 0.1nm e_HgA ?=- rms uncertainty on HgA (G1)
96- 99 F4.2 0.1nm e_HgF ?=- rms uncertainty on HgF (G1)
101-104 F4.2 0.1nm e_Fe4383 ?=- rms uncertainty on Fe4383 (G1)
106-109 F4.2 0.1nm e_Ca4455 ?=- rms uncertainty on Ca4455 (G1)
111-114 F4.2 0.1nm e_Fe4531 ?=- rms uncertainty on Fe4531 (G1)
116-119 F4.2 0.1nm e_Fe4668 ?=- rms uncertainty on Fe4668 (G1)
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Note (1): Approximate S/N per pixel measured at 5000Å of the initial
one-dimensional spectra, not degraded to the resolution of the
Lick system.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 32 A32 --- ID Globular cluster or Group name
33- 36 F4.2 0.1nm Hb Hbeta spectral index
38- 41 F4.2 0.1nm Fe5015 Fe5015 spectral index
43- 48 F6.3 mag Mg1 Mg1 spectral index
50- 54 F5.3 mag Mg2 Mg2 spectral index
56- 59 F4.2 0.1nm Mgb Mgb spectral index
61- 65 F5.2 0.1nm Fe5270 Fe5270 spectral index
67- 71 F5.2 0.1nm Fe5335 Fe5335 spectral index
73- 77 F5.2 0.1nm Fe5406 Fe5406 spectral index
79- 82 F4.2 0.1nm e_Hb rms uncertainty on Hb (G1)
84- 87 F4.2 0.1nm e_Fe5015 rms uncertainty on Fe5015 (G1)
89- 93 F5.3 mag e_Mg1 rms uncertainty on Mg1 (G1)
95- 99 F5.3 mag e_Mg2 rms uncertainty on Mg2 (G1)
101-104 F4.2 0.1nm e_Mgb rms uncertainty on Mgb (G1)
106-109 F4.2 0.1nm e_Fe5270 rms uncertainty on Fe5270 (G1)
111-114 F4.2 0.1nm e_Fe5335 rms uncertainty on Fe5335 (G1)
116-119 F4.2 0.1nm e_Fe5406 rms uncertainty on Fe5406 (G1)
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Global notes:
Note (G1): Errors determined from bootstrapping the object spectrum
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 08-Jun-2007