J/A+A/366/498 VI photometry of M33 star clusters (Chandar+, 2001)
Star clusters in M33. IV. A new survey from deep HST images.
Chandar R., Bianchi L., Ford H. C.
<Astron. Astrophys. 366, 498 (2001)>
=2001A&A...366..498C 2001A&A...366..498C
ADC_Keywords: Clusters, globular ; Photometry, VRI
Mission_Name: HST
Keywords: galaxies: individual (M33) - galaxies: star clusters -
galaxies: evolution
Abstract:
We have detected 102 star clusters in M 33, from 35 deep Hubble Space
Telescope (HST) WFPC2 fields taken from our program and from the HST
archive. Twenty-eight fields have V and I band imaging, and an
additional seven fields are imaged in a single V filter. Eighty-two of
the clusters were previously unknown. Integrated photometry reveals
that 25 clusters have (V-I) colors typical of those found in Galactic
globular clusters (only ten of these objects were previously known).
Our discovery of 15 new globular cluster candidates increases previous
estimates of the old cluster population in M 33 by ∼60%. An additional
eleven objects (only two were previously known) have colors expected
for intermediate age clusters. The new clusters have a range of ages
from 6 million years to >15Gyrs, and masses between
102M☉-106M☉, although these parameters are estimated
from only one color.
Description:
File table2 contains coordinates and photometric properties of compact
M33 clusters discovered in Hubble Space Telescope WFPC2 V and I band
images. The columns contain: identification, RA (J2000), DEC (J2000),
galactocentric distance (kpc), apparent V magnitude, radius used to
measure color, Johnson-Cousins (V-I) color, cross identification of
objects with Christian & Schommer (1988AJ.....95..704C 1988AJ.....95..704C) and Mochejska
et al. (1998AcA....48..455M 1998AcA....48..455M), previously published V magnitude if
available, previously published (V-I) color if available, and
estimated core radius.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 96 102 M33 clusters detected in deep HST WFPC2 fields
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See also:
J/ApJS/122/431 : Star Clusters in M33. I. (Chandar+, 1999)
J/AJ/121/861 : BVI photometry of central part of M33 (Macri+, 2001)
J/AJ/121/870 : Variables in the central part of M33 BVI phot. (Macri+, 2001)
J/AJ/110/1649 : HST VI photometry near the M33 nucleus (Mighell+ 1995)
J/AJ/110/2715 : UBV photometry in NGC 6822, M31 and M33 (Massey+ 1995)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID Identification Number (1)
5 I1 h RAh Right ascension (J2000)
7- 8 I2 min RAm Right ascension (J2000)
10- 14 F5.2 s RAs Right ascension (J2000)
16- 17 I2 deg DEd Declination (J2000)
19- 20 I2 arcmin DEm Declination (J2000)
22- 26 F5.2 arcsec DEs Declination (J2000)
28- 30 F3.1 kpc Dist Deprojected galactocentric distance
32- 37 F6.3 mag Vmag Apparent V magnitude (measured in 2.2" radius)
38- 39 A2 --- u_Vmag [: ] Uncertainty flag on Vmag (2)
41- 45 F5.3 mag e_Vmag ? Formal uncertainty in V magnitude (3)
47- 49 F3.1 arcsec Crad ? Color radius (4)
51- 55 F5.3 mag V-I ? Johnson-Cousins (V-I) color
57- 61 F5.3 mag e_V-I ? Uncertainty in (V-I) color (3)
63- 79 A17 --- Com Comments and Cross- identification (5)
81- 85 F5.2 mag Vmagp ? Previously published V magnitude
87- 90 F4.2 mag V-Ip ? Previously published (V-I) color
92- 95 F4.2 pc Radc ? Core radius
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Note (1): Cluster numbering begins at 61, since this catalog is a continuation
of our previous survey of M33 clusters (Chandar, Bianchi & Ford,
1999, Cat. J/ApJS/122/431).
Note (2): The V magnitude is measured in a 2.2 arcsecond radius unless otherwise
noted. A colon (:) after the V magnitude indicates that the total V
magnitude was measured in a 2.7 arcsecond aperture to include most of
the cluster extent. A double colon (::) indicates that the cluster
is located near the edge of a CCD, resulting in the use of a smaller
aperture for the V magnitude (typically 0.8 arcseconds).
Note (3): The quoted errors are 1σ formal errors from the PHOT task in
IRAF, and include counting statistics, gain, and background
variations. Given that the objects are extended, the uncertainties
are not significant for absolute comparison with different sets of
data.
Note (4): Radius for (V-I) color measurement given in Core radius.
Note (5): COmparison photometry:
CS: taken from Christian & Schommer (1988AJ.....95..704C 1988AJ.....95..704C)
MKKSS: taken from Mochejska et al. (1998AcA....48..455M 1998AcA....48..455M)
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References:
Chandar et al., Paper I 1999ApJS..122..431C 1999ApJS..122..431C = Cat. J/ApJS/122/431
Chandar et al., Paper II 1999ApJ...517..668C 1999ApJ...517..668C
Chandar et al., Paper III 1999PASP..111..794C 1999PASP..111..794C
(End) Rupali Chandar [Johns Hopkins Univ.], Patricia Bauer [CDS] 28-Nov-2000