J/A+A/435/65 UBVI photometry of NGC 6872 clusters population (Bastian+, 2005)
The star cluster population in the tidal tails of NGC 6872.
Bastian N., Hempel H., Kissler-Patig M., Homeier N., Trancho G.
<Astron. Astrophys. 435, 65 (2005)>
=2005A&A...435...65B 2005A&A...435...65B
ADC_Keywords: Associations, stellar ; Photometry, UBVRI
Keywords: galaxies: star clusters - galaxies: interactions -
galaxy: individual: NGC 6872
Abstract:
We present a photometric analysis of the rich star cluster population
in the tidal tails of NGC 6872. We find star clusters with ages
between 1-100Myr distributed in the tidal tails, while the tails
themselves have an age of less than 150Myr. Most of the young massive
(104≤M/M_☉≤107) clusters are found in the outer regions of
the galactic disk or the tidal tails. The mass distribution of the
cluster population can be well described by a power-law of the form
N(m)∝m-alpha, where alpha=1.85±0.11, in very good
agreement with other young cluster populations found in a variety of
different environments. We estimate the star formation rate for three
separate regions of the galaxy, and find that the eastern tail is
forming stars at ∼2 times the rate of the western tail and ∼5 times
the rate of the main body of the galaxy. By comparing our observations
with published N-body models of the fate of material in tidal tails in
a galaxy cluster potential, we see that many of these young clusters
will be lost into the intergalactic medium. We speculate that this
mechanism may also be at work in larger galaxy clusters such as
Fornax, and suggest that the so-called ultra-compact dwarf galaxies
could be the most massive star clusters that have formed in the tidal
tails of an ancient galactic merger.
Description:
Photometric and derived properties for the star cluster candidates in
the interacting galaxy NGC 6872. The table provides the ID, position,
photometry and errors, the reduced chi-squared of the best fitting
model, the extinction, age, and mass of the best fitting model, and
the absolute magnitude of the source correcting for the distance and
reddening.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 118 118 Cluster positions, magnitudes and derived properties
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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- 3 I3 --- Seq Sequential number of the cluster candidate
5- 6 I2 h RAh Right ascension (J2000.0)
8- 9 I2 min RAm Right ascension (J2000.0)
11- 16 F6.3 s RAs Right ascension (J2000.0)
18 A1 --- DE- Declination sign (J2000.0)
19- 20 I2 deg DEd Declination (J2000.0)
22- 23 I2 arcmin DEm Declination (J2000.0)
25- 29 F5.2 arcsec DEs Declination (J2000.0)
31- 36 F6.1 pix Xpos X position of the source (1)
38- 43 F6.1 pix Ypos Y position of the source (1)
45- 49 F5.2 mag Umag U magnitude of the source(2)
51- 54 F4.2 mag e_Umag Error in the U mag
56- 60 F5.2 mag Bmag B magnitude of the source(2)
62- 65 F4.2 mag e_Bmag Error in the B mag
67- 71 F5.2 mag Vmag V magnitude of the source(2)
73- 76 F4.2 mag e_Vmag Error in the V mag
78- 82 F5.2 mag Icmag Cousins I magnitude of the source(2)
84- 87 F4.2 mag e_Icmag Error in the Ic mag
89- 92 F4.2 --- chi2 Reduced chi-squared of the best fitting model
94- 97 F4.2 mag AV Total V-band extinction of the source
99-103 F5.2 [yr] logAge Logarithmic best fitting age of the source
105-108 F4.2 [solMass] logMass Logarithmic best fitting mass of the source
110-115 F6.2 mag VMAG Absolute magnitude of the source (3)
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Note (1): Pixel coordinates used in Figs. 6-8 of the paper
Note (2): The magnitudes are only corrected for foreground extinction
Note (3): Absolute magnitude corrected for the derived extinction
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Acknowledgements: Nate Bastian, bastian(at)astro.uu.nl
(End) Nate Bastian [Utrecht, Netherlands], Patricia Vannier [CDS] 01-Mar-2005