J/A+A/369/812 UVKs photometry of globular clusters in NGC 5128 (Rejkuba, 2001)
Deep VLT search for globular clusters in NGC 5128 :
Color-magnitude diagrams and globular cluster luminosity function.
Rejkuba M.
<Astron. Astrophys. 369, 812 (2001)>
=2001A&A...369..812R 2001A&A...369..812R
ADC_Keywords: Clusters, globular ; Photometry
Keywords: galaxies: star clusters - galaxies: formation -
galaxies: individual: NGC 5128
Abstract:
At the distance of NGC 5128 (3.6±0.2Mpc) it is possible to resolve
globular clusters with high resolution imaging from the ground, thus
allowing the globular cluster candidate selection primarily through
their morphological properties. I report the discovery of 71 globular
clusters in NGC 5128 on VLT UT1+FORS1 images, including the faintest
members (MV~-5) known to date in this galaxy as well as in 5
previously-known clusters. U- and V-band photometry has been measured
for all the candidates and the luminosity function, spanning
-10.1<MV←4.9 and -9.3<MU←3.3, constructed. These are the deepest
globular cluster luminosity functions in an elliptical galaxy
determined so far. The Kolmogorov-Smirnov statistics show that the
difference between the globular cluster luminosity functions of NGC
5128 and the Milky Way is not larger than the difference between the
ones of M 31 and the Milky Way. The (U-V)0 color histogram shows a
bimodal distribution. For 23 globular clusters I obtained K-band
images with SOFI at the NTT in La Silla. Their positions in the (U-V)
vs. (V-K) color-color diagram indicate that they are indeed old
globular clusters. Assuming that the globular clusters in NGC 5128
span a similar age range as the ones in the Milky Way and adopting a
linear fit between the metallicity and (U-V)0 color, the metal-rich
clusters peak at [Fe/H]=-0.6dex and the metal-poor ones peak at
[Fe/H]=-1.7dex.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 108 78 Coordinates, photometry, FWHM (fV and fU),
ellipticities (ellV and ellU) and projected
galactocentric distance of globular cluster
candidates
table4.dat 99 53 Same as table3, but for other extended objects,
some of which might well be globular clusters
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Table 2: Comparison with the data from literature
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ID1 ID2 Bpg Vpg VWash VWFI (U-V)
[R2001b] [VHH81]
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f1.GC-13 C36 19.04 18.24 18.27 18.39 0.91
f1.GC-16 C37 19.24 18.17 18.46 18.47 1.33
f1.GC-23 C38 19.00 18.40 1.16
f2.GC-26 C15 19.76 18.62 18.58 1.40
f2.GC-81 C12 18.82 17.74 17.79 18.01 1.47
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Notes: ID2: numbering from Hesser et al., 1984ApJ...276..491H 1984ApJ...276..491H and
1986ApJ...303L..51H 1986ApJ...303L..51H, [VHH81] NN in Simbad
Bpg and Vpg: photographic plate measurements of five clusters in
Hesser et al. (1986ApJ...303L..51H 1986ApJ...303L..51H, 1984ApJ...276..491H 1984ApJ...276..491H)
VWash: Washington photometry in Harris et al. (1992AJ....104..613H 1992AJ....104..613H)
VWFI and (U-V): This work measurements (WFI = Wide Field Imager).
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Byte-by-byte Description of file: table3.dat table4.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- [R2001b] Object name
10- 11 I2 h RAh Right ascension (J2000)
12 A1 --- --- [:]
13- 14 I2 min RAm Right ascension (J2000)
15 A1 --- --- [:]
16- 20 F5.2 s RAs Right ascension (J2000)
22 A1 --- DE- Declination sign (J2000)
23- 24 I2 deg DEd Declination (J2000)
25 A1 --- --- [:]
26- 27 I2 arcmin DEm Declination (J2000)
28 A1 --- --- [:]
29- 32 F4.1 arcsec DEs Declination (J2000)
34- 38 F5.2 mag Vmag Bessel V magnitude
40- 43 F4.2 mag e_Vmag rms uncertainty on Vmag
45- 49 F5.2 mag Umag Bessel U magnitude
50 A1 --- u_Umag Uncertainty flag on Umag
52- 55 F4.2 mag e_Umag rms uncertainty on Umag
56 A1 --- ueUmag Uncertainty flag on e_Umag
57- 61 F5.2 mag Ksmag ? Ks magnitude
63- 66 F4.2 mag e_Ksmag ? rms uncertainty on Ksmag
68- 71 F4.2 pix FWMHV ? V-band FWHM (1 pix = 0.2")
73- 76 F4.2 pix FWMHU ? U-band FWHM (1 pix = 0.2")
77 A1 --- u_FWMHU Uncertainty flag on FWMHU
79- 82 F4.2 --- ellV ? Ellipticity in V
84- 87 F4.2 --- ellU ? Ellipticity in U
88 A1 --- u_ellU Uncertainty flag on eU
90- 94 F5.2 kpc R Projected galactocentric distance
96-102 A7 --- Note Note (1)
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Note (1): Comments:
b = near bright (saturated) star
e = near edge of the field
u = marginal or no detection
v = object saturated in V; V mag from WFI data
n = object does not satisfy all the criteria for globular cluster
classification
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History:
From electronic version of the journal
(End) James Marcout, Patricia Bauer [CDS] 10-Sep-2001