J/AJ/133/2764 M31 globular clusters structural parameters (Barmby+, 2007)
Structural parameters for globular clusters in M 31 and generalizations for the
fundamental plane.
Barmby P., McLaughlin D.E., Harris W.E., Harris G.L.H., Forbes D.A.
<Astron. J., 133, 2764-2786 (2007)>
=2007AJ....133.2764B 2007AJ....133.2764B
ADC_Keywords: Galaxies, nearby ; Clusters, globular ; Morphology ; Photometry
Keywords: galaxies: individual (M31) - galaxies: star clusters -
globular clusters: general
Abstract:
The structures of globular clusters (GCs) reflect their dynamical
states and past histories. High-resolution imaging allows the
exploration of morphologies of clusters in other galaxies. Surface
brightness profiles from new Hubble Space Telescope observations of 34
GCs in M31 are presented, together with fits of several different
structural models to each cluster. M31 clusters appear to be
adequately fit by standard King models and do not obviously require
alternate descriptions with relatively stronger halos, such as are
needed to fit many GCs in other nearby galaxies. The derived
structural parameters are combined with corrected versions of those
measured in an earlier survey in order to construct a comprehensive
catalog of structural and dynamical parameters for M31 GCs with a
sample size similar to that for the Milky Way. Clusters in M31, the
Milky Way, Magellanic Clouds, the Fornax dwarf spheroidal, and NGC
5128 define a very tight fundamental plane with identical slopes. The
combined evidence for these widely different galaxies strongly
reinforces the view that old GCs have near-universal structural
properties, regardless of host environment.
Description:
We have used material from several different HST programs.
Program GO-10260 (PI: W. Harris) obtained ACS Wide Field Channel (WFC)
images centered on 6 clusters in M31 and 12 clusters in NGC 5128,
selected to have MV←10.5 and (for M31) no previous HST
observations.
Program GO-9719 (PI: T. Bridges) obtained ACS High Resolution Channel
(HRC) images of three M31 clusters, using exposure times of 2020 s in
F606W and 2680s in F814W in 2003 August and September.
Program GO-8664 (PI: W. Harris) targeted 24 M31 clusters with a range
of properties for imaging with STIS in snapshot mode; exposure times
were 480s in the unfiltered 50CCD/CL imaging mode. These data were
obtained in fall 2000 and winter 2001.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 101 94 Integrated measurements for M31 clusters
table2.dat 47 3349 F606W, F814W, or V intensity profiles for 33 GCs
table4.dat 147 209 Basic parameters of fits to 49 profiles of 33 GCs
table5.dat 166 161 Derived structural and photometric parameters
table6.dat 184 160 Derived dynamical parameters of GCs in M31
table7.dat 79 161 Galactocentric radii and κ-space parameters
table8.dat 152 161 Predicted aperture velocity dispersions
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See also:
J/AJ/119/727 : M31 globular clusters photometry (Barmby+, 2000)
J/AJ/123/2490 : RV and [Fe/H] of M31 globular cluster system (Perrett+, 2002)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 48 A48 --- Prog Program
50- 54 A5 --- Name M31 cluster name
55 A1 --- f_Name [*] cluster near edge (1)
57- 60 F4.2 --- eps Average ellipticity
62- 64 I3 deg PA ? Position angle (2)
66- 70 F5.2 mag Vmag The F606W band magnitude (3)
72- 76 F5.2 mag Imag ? The F814W band magnitude
78- 81 F4.2 mag E(B-V) The (B-V) color excess
83- 87 F5.2 kpc RGC Galactocentric distance
89- 93 F5.2 [-] [Fe/H] Metallicity
95- 97 F3.1 [-] e_[Fe/H] Error in [Fe/H]
99-101 A3 --- r_[Fe/H] Reference for [Fe/H] (4)
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Note (1): the asterisk (*) indicates a cluster close to the image edge; its
measurements do not cover the full range of radial distance.
Note (2): Measured East of North.
Note (3): F606W for ACS-observed clusters, except G001 (F555W).
Note (4): References as follows:
HBK = Huchra et al., 1991ApJ...370..495H 1991ApJ...370..495H, HBK NNN-NNN
P02 = Perrett et al., 2002, Cat. J/AJ/123/2490
B00 = Barmby et al., 2000, Cat. J/AJ/119/727, [BHB2000] NNN-NNN
AVE = no measurement: [Fe/H]=-1.2pm0.6 assigned
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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- 5 A5 --- Name M31 cluster name
7- 10 A4 --- Det Detector (HRC, STIS, WFC)
12- 15 A4 --- Filt Filter (F555, F606, F814 or V)
17- 23 F7.4 arcsec Rad Radius
25- 34 F10.3 solLum/pc2 Int Intensity
36- 43 F8.3 solLum/pc2 e_Int Uncertainty in Int
45- 47 A3 --- Flag Profile flag (1)
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Note (1): Profile flag as follows:
BAD = the intensity value is deemed dubious because it strongly
deviates from its neighbors or is obviously affected by nearby
bright stars or image artifacts.
SAT = the isophotal intensity is above the imposed saturation limit
of 70cts/s/pix.
DEP = the radius is inside R<2pix=0.1" and the isophotal intensity is
dependent on its neighbors. The ELLIPSE output includes
brightnesses for 15 radii inside 2 pixels, but these are all
measured from the same 13 central pixels and are clearly not
statistically independent. To avoid excessive weighting of the
central regions of the cluster in the fits, only intensities
at radii Rmin, Rmin+(0.5, 1.0, 2.0px), R>2.5px, were used.
OK = none of the above apply and the point is used in model fitting
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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- 5 A5 --- Name M31 cluster name
7- 14 A8 --- De/Fi Detector/Filter combination
16- 20 F5.3 mag AV Extinction in the F606W band
22- 27 F6.3 mag Vcol Color term (1)
29- 33 F5.3 mag e_Vcol Error in Vcol
35- 36 I2 --- Npts Number of ok points in intensity profile
38- 40 A3 --- Mod Model used (G1)
42- 48 F7.2 --- Chi2 Model χ2min (2)
50- 56 F7.2 solLum/pc2 Ibkg Best-fit background intensity
58- 62 F5.2 solLum/pc2 e_Ibkg Error in Ibkg
64- 68 F5.2 --- W0 Central dimensionless potential of best fit
70- 73 F4.2 --- E_W0 Upper limit error in W0
75- 78 F4.2 --- e_W0 Lower limit error in W0
80- 83 F4.2 --- c/n Concentration or Sersic index of best fit
85- 88 F4.2 --- E_c/n Upper limit error in c/n
90- 93 F4.2 --- e_c/n Lower limit error in c/n
95- 99 F5.2 mag/arcsec2 mu0 Surface brightness (3)
101-104 F4.2 mag/arcsec2 E_mu0 Upper limit error in mu0
106-109 F4.2 mag/arcsec2 e_mu0 Lower limit error in mu0
111-116 F6.3 [arcsec] logra Log of the angular scale radius
118-122 F5.3 [arcsec] E_logra Upper limit error in logra
124-128 F5.3 [arcsec] e_logra Lower limit error in logra
130-135 F6.3 [pc] logrp Log of the physical scale radius (4)
137-141 F5.3 [pc] E_logrp Upper limit error in logrp
143-147 F5.3 [pc] e_logrp Lower limit error in logrp
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Note (1): To transform photometry from the native bandpass of the data to
the standard V scale.
Note (2): Obtained for that class of model (without the re-scaling applied
for uncertainty estimation).
Note (3): Calibrated and extinction-corrected in the native bandpass
of the data.
Note (4): Obtained from the angular scale assuming D=780kpc for M31.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Name M31 cluster name
7- 14 A8 --- De/Fi Detector/Filter combination
16- 18 A3 --- Mod Model used (G1)
20- 24 F5.2 [pc] logRt Log of model tidal radius (1)
26- 29 F4.2 [pc] E_logRt Upper limit error in logRt
31- 34 F4.2 [pc] e_logRt Lower limit error in logRt
36- 41 F6.3 [pc] logRc Log of model projected core radius
43- 47 F5.3 [pc] E_logRc Upper limit error in logRc
49- 53 F5.3 [pc] e_logRc Lower limit error in logRc
55- 60 F6.3 [pc] logRh Log of model projected half-light or
effective radius
62- 66 F5.3 [pc] E_logRh Upper limit error in logRh
68- 72 F5.3 [pc] e_logRh Lower limit error in logRh
74- 78 F5.3 [-] logh/c Log the projected half-light radius to
core radius (2)
80- 84 F5.3 [-] E_logh/c Upper limit error in logh/c
86- 90 F5.3 [-] e_logh/c Lower limit error in logh/c
92- 95 F4.2 [solLum/pc2] logI0 Log of best-fit central V band luminosity
surface density
97-100 F4.2 [solLum/pc2] E_logI0 Upper limit error in logI0
102-105 F4.2 [solLum/pc2] e_logI0 Lower limit error in logI0
107-110 F4.2 [solLum/pc3] logj0 Log of central V band luminosity volume
density (3)
112-115 F4.2 [solLum/pc3] E_logj0 Upper limit error in logj0
117-120 F4.2 [solLum/pc3] e_logj0 Lower limit error in logj0
122-125 F4.2 [solLum] logL Log of total integrated V band model
luminosity
127-130 F4.2 [solLum] E_logL Upper limit error in logL
132-135 F4.2 [solLum] e_logL Lower limit error in logL
137-141 F5.2 mag Vmag Total extinction-corrected apparent V
band magnitude of a model cluster
143-146 F4.2 mag E_Vmag Upper limit error in Vmag
148-151 F4.2 mag e_Vmag Lower limit error in Vmag
153-156 F4.2 [solLum/pc2] logIh Log of V band luminosity
surface density (4)
158-161 F4.2 [solLum/pc2] E_logIh Upper limit error in logIh
163-166 F4.2 [solLum/pc2] e_logIh Lower limit error in logIh
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Note (1): Always infinite for Sersic models.
Note (2): A measure of cluster concentration.
Note (3): For Sersic models the density at the 3-D radius r0.
Note (4): Averaged over the half-light/effective radius.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Name M31 cluster name
7- 14 A8 --- De/Fi Detector/Filter combination
16- 20 F5.3 Sun M/L Mass-to-light ratio (1)
22- 26 F5.3 Sun E_M/L Upper limit error in M/L
28- 32 F5.3 Sun e_M/L Lower limit error in M/L
34- 36 A3 --- Mod Model used (G1)
38- 41 F4.2 [solMass] logM Log of integrated model mass
43- 46 F4.2 [solMass] E_logM Upper limit error in logM
48- 51 F4.2 [solMass] e_logM Lower limit error in logM
53- 57 F5.2 [10-7J] logE Log of integrated binding energy
in units of erg
59- 62 F4.2 [10-7J] E_logE Upper limit error in logE
64- 67 F4.2 [10-7J] e_logE Lower limit error in logE
69- 72 F4.2 [solMass/pc2] logS0 Log of central surface mass density
74- 77 F4.2 [solMass/pc2] E_logS0 Upper limit error in logS0
79- 82 F4.2 [solMass/pc2] e_logS0 Lower limit error in logS0
84- 88 F5.2 [solMass/pc3] logrho Log of central volume density (2)
90- 93 F4.2 [solMass/pc3] E_logrho Upper limit error in logrho
95- 98 F4.2 [solMass/pc3] e_logrho Lower limit error in logrho
100-103 F4.2 [solMass/pc2] logSh Log of surface mass density
averaged over the effective
radius Rh
105-108 F4.2 [solMass/pc2] E_logSh Upper limit error in logSh
110-113 F4.2 [solMass/pc2] e_logSh Lower limit error in logSh
115-119 F5.3 [km/s] logsig Log of predicted line-of-sight
velocity dispersion (3)
121-125 F5.3 [km/s] E_logsig Upper limit error in logsig
127-131 F5.3 [km/s] e_logsig Lower limit error in logsig
133-137 F5.3 [km/s] logvel Log of predicted central escape
velocity
139-143 F5.3 [km/s] E_logvel Upper limit error in logvel
145-149 F5.3 [km/s] e_logvel Lower limit error in logvel
151-155 F5.2 [yr] logtau Log of two-body relaxation time (4)
157-160 F4.2 [yr] E_logtau Upper limit error in logtau
162-165 F4.2 [yr] e_logtau Lower limit error in logtau
167-172 F6.3 [solMass.s3/km3/pc3] logf0 Log of measure of the model's
central phase-space density or
relaxation time (5)
174-178 F5.3 [solMass.s3/km3/pc3] E_logf0 Upper limit error in logf0
180-184 F5.3 [solMass.s3/km3/pc3] e_logf0 Lower limit error in logf0
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Note (1): Adopted for each object from the analysis in Section 4.
The values assume an age of 13Gyr for all clusters. The error bars
include a ±2Gyr uncertainty in age, as well as the previously
tabulated uncertainties in [Fe/H].
Note (2): For Sersic models the density at the 3-D radius r0.
Note (3): At the cluster center (or at Rc for Sersic models).
Note (4): At the model projected half-mass radius.
Note (5): At r0 for Sersic models.
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Name M31 cluster name
7- 14 A8 --- De/Fi Detector/Filter combination
16- 20 F5.2 kpc RGC Galactocentric distance
22- 24 A3 --- Mod Model used (G1)
26- 31 F6.3 --- kappam1 The κm,1 parameter (1)
33- 37 F5.3 --- E_kappam1 Upper limit error in kappam1
39- 43 F5.3 --- e_kappam1 Lower limit error in kappam1
45- 49 F5.3 --- kappam2 The κm,2 parameter (1)
51- 55 F5.3 --- E_kappam2 Upper limit error in kappam2
57- 61 F5.3 --- e_kappam2 Lower limit error in kappam2
63- 67 F5.3 --- kappam3 The κm,3 parameter (1)
69- 73 F5.3 --- E_kappam3 Upper limit error in kappam3
75- 79 F5.3 --- e_kappam3 Lower limit error in kappam3
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Note (1): Modified versions of the κ parameters of Bender et al.
(1992ApJ...399..462B 1992ApJ...399..462B), who found that early-type galaxies and
(separately) globular clusters defined the edges of planes in κ
space. We define the parameters using mass rather than luminosity
surface density, as this is more useful for comparing globulars to
younger clusters and galaxies (see McLaughlin et al.,
2008MNRAS.384..563M 2008MNRAS.384..563M), and emphasize this by using the notation
κm,i.
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Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Name M31 cluster name
7- 14 A8 --- De/Fi Detector/Filter combination
16- 20 F5.3 solMass/solLum M/L The mass-to-light ratio
22- 26 F5.3 solMass/solLum E_M/L Upper limit error in M/L
28- 32 F5.3 solMass/solLum e_M/L Lower limit error in M/L
34- 36 A3 --- Mod Model used (G1)
38- 43 F6.3 [pc] logRhp Log of the physical scale radius (1)
45- 50 F6.3 [arcsec] logRha Log of the angular scale radius
52- 56 F5.3 [arcsec] E_logRha Upper limit error in logRha
58- 62 F5.3 [arcsec] e_logRha Lower limit error in logRha
64- 68 F5.3 [km/s] logsR/8 Log of predicted velocity dispersion
within Rh/8
70- 74 F5.3 [km/s] E_logsR/8 Upper limit error in logsR/8
76- 80 F5.3 [km/s] e_logsR/8 Lower limit error in logsR/8
82- 86 F5.3 [km/s] logsR/4 Log of predicted velocity dispersion
within Rh/4
88- 92 F5.3 [km/s] E_logsR/4 Upper limit error in logsR/4
94- 98 F5.3 [km/s] e_logsR/4 Lower limit error in logsR/4
100-104 F5.3 [km/s] logsR Log of predicted velocity dispersion
within Rh
106-110 F5.3 [km/s] E_logsR Upper limit error in logsR
112-116 F5.3 [km/s] e_logsR Lower limit error in logsR
118-122 F5.3 [km/s] logs4R Log of predicted velocity dispersion
within 4Rh
124-128 F5.3 [km/s] E_logs4R Upper limit error in logs4R
130-134 F5.3 [km/s] e_logs4R Lower limit error in logs4R
136-140 F5.3 [km/s] logs8R Log of predicted velocity dispersion
within 8Rh
142-146 F5.3 [km/s] E_logs8R Upper limit error in logs8R
148-152 F5.3 [km/s] e_logs8R Lower limit error in logs8R
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Note (1): Obtained from the angular scale assuming D=780kpc for M31.
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Global Notes:
Note (G1): the models are:
K66 = King 1966AJ.....71...64K 1966AJ.....71...64K
W = Wilson 1975AJ.....80..175W 1975AJ.....80..175W
S = Sersic 1968 (model in R1/n)
History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 27-May-2009