J/A+A/455/453 Globular Cluster System of NGC5846 (Chies-Santos+, 2006)
The globular cluster system of NGC 5846 revisited: colours, sizes and
X-ray counterparts.
Chies-Santos A.L., Pastoriza M.G., Santiago B.X., Forbes D.A.
<Astron. Astrophys. 455, 453 (2006)>
=2006A&A...455..453C 2006A&A...455..453C
ADC_Keywords: Clusters, globular ; X-ray sources ; Photometry, HST
Keywords: Galaxies: individual: NGC 5846 - galaxies: star clusters -
X-rays: galaxies
Abstract:
NGC 5846 is a giant elliptical galaxy with a previously well studied
globular cluster system (GCS), known to have a bimodal colour
distribution with a remarkably high red fraction. Here we revisit the
central galaxy regions searching for new globular cluster (GC)
candidates, and measure magnitudes, colours and sizes for them. We
also search for their X-ray counterparts.
Methods: We use archival Hubble Space Telescope WFPC2 images, from
which we modelled and subtracted the host light distribution to
increase the available sample of GCs. We performed photometry on the
central objects, and measured sizes and coordinates for the entire GC
system known in this galaxy.
Results: We detect two dozen previously unknown GC candidates in the
central reg ions. Reliable sizes are obtained for about 60 GCs; their
typical effective radii are in the range 3-5pc. The largest clusters
are located in the central regions. We find 7 X-ray counterparts to
GCs, most of them in the central region. They are among the most
luminous X-ray sources in NGC 5846. They are also optically luminous,
compact and belong to the red subpopulation.
Conclusions: The GCS of NGC 5846 is composed of relatively luminous
X-ray sources.
Description:
Table. 3 contains positions and photometry of the entire GCS of
NGC 5846;
Table 4. lists the sizes and related parameters for those GCs which
were success fully measured by ISHAPE code (Larsen, 1999A&AS..139..393L 1999A&AS..139..393L).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 71 777 Positions and photometry for the entire GCS of
NGC 5846
table4.dat 49 54 Sizes and related parameters for GCs
successfully measured by ISHAPE
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See also:
J/AJ/130/1502 : NGC 5846 group: photometry and spectroscopy (Mahdavi+, 2005)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1 A1 --- Pointing [CNS] HST/WFPC2 pointing Central, North or South
3 I1 --- Chip [1/4] HST/WFPC2 chip number
5- 10 F6.2 pix Xpix X CCD coordinate
12- 17 F6.2 pix Ypix Y CCD coordinate
19- 29 F11.7 deg RAdeg Right ascension in decimal degrees (J2000)
31- 39 F9.7 deg DEdeg Declination in decimal degrees (J2000)
41- 45 F5.2 mag Vmag V magnitude (F555W)
47- 50 F4.2 mag e_Vmag rms uncertainty on Vmag
52- 56 F5.2 mag Imag I magnitude (F814W)
58- 61 F4.2 mag e_Imag rms uncertainty on Imag
63- 66 F4.2 mag V-I V-I colour index (F555W-F814W)
68- 71 F4.2 mag e_V-I rms uncertainty on V-I
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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- 11 F11.7 deg RAdeg Right ascension in decimal degrees (J2000)
13- 21 F9.7 deg DEdeg Declination in decimal degrees (J2000)
23- 27 F5.2 mag Vmag V magnitude (F555W)
29- 33 F5.2 mag Imag I magnitude (F814W)
35- 38 F4.2 mag V-I V-I colour index (F555W-F814W)
40- 44 F5.2 pc Reff Effective radius
46- 49 F4.2 --- chiratio chi ratio (chi2/chi02)
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Acknowledgements:
Ana Leonor Chies Santiago Santos, ana.leonor(at)ufrgs.br
(End) Patricia Vannier [CDS] 19-May-2006