J/AJ/149/157 Surface intensity profiles for 10 M33 globular clusters (Ma+, 2015)
Structural parameters for 10 halo globular clusters in M33.
Ma J.
<Astron. J., 149, 157 (2015)>
=2015AJ....149..157M 2015AJ....149..157M
ADC_Keywords: Galaxies, nearby ; Clusters, globular ; Photometry ;
Abundances, [Fe/H]
Keywords: galaxies: individual: M33 - galaxies: star clusters: general -
galaxies: stellar content
Abstract:
In this paper, we present the properties of 10 halo globular clusters
(GCs) with luminosities L~=5-7x105L☉ in the Local Group galaxy
M33 using images from the Hubble Space Telescope WFPC2 in the F555W
and F814W bands. We obtained the ellipticities, position angles, and
surface brightness profiles for each GC. In general, the ellipticities
of the M33 sample clusters are similar to those of the M31 clusters.
The structural and dynamical parameters are derived by fitting the
profiles to three different models combined with mass-to-light ratios
(M/L values) from population-synthesis models. The structural
parameters include core radii, concentration, half-light radii, and
central surface brightness. The dynamical parameters include the
integrated cluster mass, integrated binding energy, central surface
mass density, and predicted line of sight velocity dispersion at the
cluster center. The velocity dispersions of the four clusters
predicted here agree well with the observed dispersions by Larsen et
al. The results here showed that the majority of the sample halo GCs
are better fitted by both the King model and the Wilson model than the
Sersic model. In general, the properties of the clusters in M33, M31,
and the Milky Way fall in the same regions of parameter spaces. The
tight correlations of cluster properties indicate a "fundamental
plane" for clusters, which reflects some universal physical conditions
and processes operating at the epoch of cluster formation.
Description:
The sample of M33 halo globular clusters in this paper is from
Sarajedini et al. (1998ApJ...508L..37S 1998ApJ...508L..37S)
The observations used in this work come from the HST program 5914, in
which the sample star clusters were observed by the HST/WFPC2 in the
F555W and F814W bands. Each cluster was centered in the PC1 chip, and
was observed with a total exposure time of 4800s in the F555W band and
5200s in the F814W band (see Sarajedini et al. 2000AJ....120.2437S 2000AJ....120.2437S for
details). We obtained the combined drizzled images from the Hubble
Legacy Archive.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 88 10 Integrated measurements of 10 halo globular
clusters in M33
table2.dat 41 1340 Intensity profiles for 10 halo globular
clusters in M33
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See also:
VII/202 : Globular Clusters in the Milky Way (Harris, 1997)
J/AJ/146/20 : Structural parameters for 79 GCs in M31 (Wang+, 2013)
J/AJ/145/88 : UBVRI photometry of M33 star clusters. II. (Ma, 2013)
J/MNRAS/426/2427 : M33 star clusters structural parameters (San Roman+, 2012)
J/AJ/144/41 : UBVRI photometry of M33 star clusters. I. (Ma+, 2012)
J/ApJ/700/103 : Ages of star clusters in M33 (Park+, 2009)
J/AJ/131/2478 : M31 and M33 UBVRI photometry (Massey+, 2006)
J/ApJS/122/431 : Star Clusters in M33 (Chandar+, 1999)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Name Cluster identifier
6- 9 F4.2 --- Ell1 [0/0.4] Ellipticity of the F555W filter
11- 14 F4.2 --- e_Ell1 [0.01/0.04] Uncertainty in Ell1
16- 18 I3 deg PA1 [-36/43] Position angle θ of the F555W
filter
20- 21 I2 deg e_PA1 [2/27] Uncertainty in PA1
23- 26 F4.2 --- Ell2 [0.1/0.3] Ellipticity of the F814W filter
28- 31 F4.2 --- e_Ell2 [0.01/0.05] Uncertainty in Ell2
33- 35 I3 deg PA2 [-63/40] Position angle θ of the F814W
filter
37- 38 I2 deg e_PA2 [1/17] Uncertainty in PA2
40- 44 F5.2 mag Bmag Cluster B-band magnitude
46- 50 F5.2 mag Vmag Cluster V-band magnitude
52- 56 F5.2 mag Imag Cluster I-band magnitude
58- 61 F4.2 --- Rgc [0.6/4.4] Cluster galactocentric distance
63- 66 F4.2 mag E(B-V) [0/0.4] The (B-V) color excess
68- 72 F5.2 [Sun] [Fe/H] [-2.2/-0.2] Cluster metallicity
74- 77 F4.2 [Sun] e_[Fe/H] [0.04/0.11] Uncertainty in [Fe/H]
79- 83 F5.2 Gyr Age [1.2/18.7] Cluster age
85- 88 F4.2 Gyr e_Age [0.05/0.41] Uncertainty in Age
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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- 4 A4 --- Name Cluster identifier
6- 10 A5 --- Band Band used in the observation (F555W or F814W)
12- 18 F7.4 arcsec Rad [0/13] Cluster-centric radius
20- 28 F9.3 Lsun/pc2 Int [-7/61415] Final, calibrated intensity (1)
30- 37 F8.3 Lsun/pc2 e_Int [0.06/1662] Uncertainty in Int
39- 41 A3 --- f_Int Profile flag (OK, BAD, or DEP) (2)
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Note (1): No extinction correction applied.
Note (2): The flag codes are defined as below:
OK = Used to constrain the model fit;
DEP = May lead to excessive weighting of the central regions of the cluster;
BAD = An individual isophote that deviated strongly from its neighbors or
showed irregular features and thus was deleted by hand.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 22-May-2015