J/AJ/144/191 Multicolor photometry of 135 star clusters in M31 (Wang+, 2012)
Age and mass studies for young star clusters in M31 from SEDS-FIT.
Wang S., Ma J., Fan Z., Wu Z., Zhang T., Zou H., Zhou X.
<Astron. J., 144, 191 (2012)>
=2012AJ....144..191W 2012AJ....144..191W
ADC_Keywords: Galaxies, nearby ; Associations, stellar ; Photometry, UBVRI ;
Photometry, infrared ; Photometry, SDSS ;
Photometry, ultraviolet
Keywords: galaxies: individual: M31 - galaxies: star clusters: general -
galaxies: stellar content
Abstract:
In this paper, we present photometry for young star clusters in M31,
which are selected from Caldwell et al. These star clusters have been
observed as part of the Beijing-Arizona-Taiwan-Connecticut (BATC)
Multicolor Sky Survey from 1995 February to 2008 March. The BATC
images including these star clusters are taken with 15
intermediate-band filters covering 3000-10000Å. Combined with
photometry in the GALEX far- and near-ultraviolet, broadband UBV RI,
SDSS ugriz, and infrared JHKs of Two Micron All Sky Survey, we
obtain their accurate spectral energy distributions (SEDs) from 1538
to 20000Å. We derive these star clusters' ages and masses by
comparing their SEDs with stellar population synthesis models. Our
results are in good agreement with previous determinations. The mean
value of age and mass of young clusters (<2Gyr) is about 385Myr and
2x104M☉, respectively. There are two distinct peaks in the age
distribution, a highest peak at age ∼60Myr and a secondary peak around
250Myr, while the mass distribution shows a single peak around
104M☉. A few young star clusters have two-body relaxation
times greater than their ages, indicating that those clusters have not
been well dynamically relaxed and therefore have not established the
thermal equilibrium. There are several regions showing aggregations of
young star clusters around the 10kpc ring and the outer ring,
indicating that the distribution of the young star clusters is well
correlated with M31's star-forming regions. The young massive star
clusters (age≤100Myr and mass≥104M☉) show apparent
concentration around the ring splitting region, suggesting a recent
passage of a satellite galaxy (M32) through M31 disk.
Description:
The sample of star clusters in this paper is selected from Caldwell et al.
(2009, cat. J/AJ/137/94; 2011, cat. J/AJ/141/61).
Our multicolor photometric data are from the GALEX FUV and NUV,
broadband UBVRI, SDSS ugriz, 15 intermediate-band filters of
Beijing-Arizona-Taipei-Connecticut (BATC) Multicolor Sky Survey, and
2MASS JHKs, which constitute the Spectral Energy Distributions (SEDs)
covering 1538-20000Å.
The M31 field is part of a galaxy calibration program of
Beijing-Arizona-Taipei-Connecticut (BATC) Multicolor Sky Survey (Zhou
et al., 1995-2005, cat. II/262). The BATC program uses the 60/90cm
Schmidt Telescope at the Xinglong Station of the National Astronomical
Observatories, Chinese Academy of Sciences (NAOC). This system
includes 15 intermediate-band filters, covering a range of wavelength
from 3000 to 10000Å (see Fan et al., 1996, cat. J/AJ/112/628, for
details). Before 2006 February, a Ford Aerospace 2k*2k thick CCD
camera was applied, which has a pixel size of 15µm and a field of
view of 58'*58', resulting in a resolution of 1.67"/pixel. After 2006
February, a new 4k*4k CCD with a pixel size of 12µm was used, with
a resolution of 1.36"/pixel (Fan et al., 2009RAA.....9..993F 2009RAA.....9..993F). We
obtained 143.9hr of imaging of the M31 field covering about 6deg2,
consisting of 447 images, through the set of 15 filters in five
observing runs from 1995 to 2008, spanning 13 years (see Fan et al.,
2009RAA.....9..993F 2009RAA.....9..993F; Wang et al., 2010, cat. J/AJ/139/1438, for
details).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 202 135 Beijing-Arizona-Taipei-Connecticut (BATC)
intermediate-band photometry of 135 sample
star clusters in M31
table2.dat 199 135 GALEX, optical broadband, SDSS, and 2MASS near-IR
photometry of 135 sample star clusters in M31
table3.dat 50 135 Ages, masses, and reddening values of 135
sample star clusters in M31
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See also:
II/312 : GALEX-DR5 (GR5) sources from AIS and MIS (Bianchi+ 2011)
II/281 : 2MASS 6X Point Source Working Database / Catalog (Cutri+ 2006)
II/262 : BATC Data Release One - BATC DR1 (Zhou+ 1995-2005)
J/ApJS/199/37 : GALEX catalog of star clusters in M31 (Kang+, 2012)
J/AJ/141/61 : Star clusters in M31. II. (Caldwell+, 2011)
J/AJ/139/1438 : SED & age estimates of 104 M31 GCs (Wang+, 2010)
J/MNRAS/402/803 : M31 globular cluster system (Peacock+, 2010)
J/AJ/137/94 : Star clusters in M31 (Caldwell+, 2009)
J/A+A/508/1285 : Metallicity estimates of M31 GCs (Galleti+, 2009)
J/ApJ/703/1872 : Compact star clusters in the M31 disk (Vansevicius+, 2009)
J/ApJS/177/174 : Star clusters in M31 (Narbutis+, 2008)
J/A+A/471/127 : New globular clusters in M31 (Galleti+, 2007)
J/ApJS/173/643 : GALEX UV photometry of M31 Globular Clusters (Rey+, 2007)
J/A+A/449/143 : Photometry of M31 globular cluster candidates (Ma+, 2006)
J/A+A/456/985 : RVs of 76 M31 candidate clusters (Galleti+, 2006)
J/AJ/131/1416 : IR Photometry of nearby globular clusters (Nantais+, 2006)
J/A+A/416/917 : Revised Bologna Catalog of M31 GCs (Galleti+, 2004)
J/AJ/119/727 : M31 globular clusters photometry (Barmby+, 2000)
J/AJ/112/628 : BATC Color Survey of M67 (Fan+ 1996)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Name Star cluster name
19- 23 F5.2 mag amag ? BATC a band magnitude (3360Å), AB scale (6)
25- 29 F5.3 mag e_amag ? 1σ uncertainty in amag
31- 35 F5.2 mag bmag ? BATC b band magnitude (3890Å), AB scale (6)
37- 41 F5.3 mag e_bmag ? 1σ uncertainty in bmag
43- 47 F5.2 mag cmag ? BATC c band magnitude (4210Å), AB scale (6)
49- 53 F5.3 mag e_cmag ? 1σ uncertainty in cmag
55- 59 F5.2 mag dmag ? BATC d band magnitude (4550Å), AB scale (6)
61- 65 F5.3 mag e_dmag ? 1σ uncertainty in dmag
67- 71 F5.2 mag emag ? BATC e band magnitude (4925Å), AB scale (6)
73- 77 F5.3 mag e_emag ? 1σ uncertainty in emag
79- 83 F5.2 mag fmag ? BATC f band magnitude (5270Å), AB scale (6)
85- 89 F5.3 mag e_fmag ? 1σ uncertainty in fmag
91- 95 F5.2 mag gmag1 ? BATC g band magnitude (5795Å), AB scale (6)
97-101 F5.3 mag e_gmag1 ? 1σ uncertainty in gmag1
103-107 F5.2 mag hmag ? BATC h band magnitude (6075Å), AB scale (6)
109-113 F5.3 mag e_hmag ? 1σ uncertainty in hmag
115-119 F5.2 mag imag1 ? BATC i band magnitude (6660Å), AB scale (6)
121-125 F5.3 mag e_imag1 ? 1σ uncertainty in imag1
127-131 F5.2 mag jmag ? BATC j band magnitude (7050Å), AB scale (6)
133-137 F5.3 mag e_jmag ? 1σ uncertainty in jmag
139-143 F5.2 mag kmag ? BATC k band magnitude (7490Å), AB scale (6)
145-149 F5.3 mag e_kmag ? 1σ uncertainty in kmag
151-155 F5.2 mag mmag ? BATC m band magnitude (8020Å), AB scale (6)
157-161 F5.3 mag e_mmag ? 1σ uncertainty in mmag
163-167 F5.2 mag nmag ? BATC n band magnitude (8480Å), AB scale (6)
169-173 F5.3 mag e_nmag ? 1σ uncertainty in nmag
175-179 F5.2 mag omag ? BATC o band magnitude (9190Å), AB scale (6)
181-185 F5.3 mag e_omag ? 1σ uncertainty in omag
187-191 F5.2 mag pmag ? BATC p band magnitude (9745Å), AB scale (6)
193-197 F5.3 mag e_pmag ? 1σ uncertainty in pmag
199-202 F4.1 arcsec Aper Aperture radius
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Note (6): BATC=Beijing-Arizona-Taipei-Connecticut Multicolor Sky Survey
(Zhou et al., 1995-2005, cat. II/262). For some objects, the
magnitudes in some filters could not be obtained because of low S/N.
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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- 17 A17 --- Name Star cluster name
19 A1 --- f_Name [a] Photometric flag on Name (1)
21- 25 F5.2 mag FUV ? GALEX FUV band magnitude, AB scale (2)
27- 31 F5.3 mag e_FUV ? Uncertainty in FUV
33- 37 F5.2 mag NUV ? GALEX NUV band magnitude, AB scale (2)
39- 43 F5.3 mag e_NUV ? Uncertainty in NUV
45- 49 F5.2 mag Umag ? Johnson U band magnitude (3)
51- 55 F5.3 mag e_Umag ? Uncertainty in Umag
57- 61 F5.2 mag Bmag ? Johnson B band magnitude (3)
63- 67 F5.3 mag e_Bmag ? Uncertainty in Bmag
69- 73 F5.2 mag Vmag ? Johnson V band magnitude (3)
75- 79 F5.3 mag e_Vmag ? Uncertainty in Vmag
81- 85 F5.2 mag Rmag ? Johnson-Cousins R band magnitude (3)
87- 91 F5.3 mag e_Rmag ? Uncertainty in Rmag
93- 97 F5.2 mag Imag ? Johnson-Cousins I band magnitude (3)
99-103 F5.3 mag e_Imag ? Uncertainty in Imag
105-109 F5.2 mag umag ? SDSS u band magnitude, AB scale (4)
111-115 F5.3 mag e_umag ? Uncertainty in umag
117-121 F5.2 mag gmag ? SDSS g band magnitude, AB scale (4)
123-127 F5.3 mag e_gmag ? Uncertainty in gmag
129-133 F5.2 mag rmag ? SDSS r band magnitude, AB scale (4)
135-139 F5.3 mag e_rmag ? Uncertainty in rmag
141-145 F5.2 mag imag ? SDSS i band magnitude, AB scale (4)
147-151 F5.3 mag e_imag ? Uncertainty in imag
153-157 F5.2 mag zmag ? SDSS z band magnitude, AB scale (4)
159-163 F5.3 mag e_zmag ? Uncertainty in zmag
165-169 F5.2 mag Jmag ? 2MASS J band magnitude (5)
171-175 F5.3 mag e_Jmag ? Uncertainty in Jmag
177-181 F5.2 mag Hmag ? 2MASS H band magnitude (5)
183-187 F5.3 mag e_Hmag ? Uncertainty in Hmag
189-193 F5.2 mag Kmag ? 2MASS Ks band magnitude (5)
195-199 F5.3 mag e_Kmag ? Uncertainty in Kmag
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Note (1):
a = We found that there was a magnitude offset (≥0.5mag) between
SDSS and UBVRI for 35 objects by transforming between the ugriz and UBVRI
bands following the transformations from Jester et al. (2005,
cat. J/AJ/130/873). Because the SDSS ugriz magnitudes provided a more
homogeneous set of photometric measurements, we adopted the SDSS magnitudes
and abandoned UBVRI magnitudes for these objects.
Note (2): From Kang et al. (2012, cat. J/ApJS/199/37).
Note (3): We adopted the original UBVRI measurements of Barmby et al. 2000
(Cat. J/AJ/119/727) as our preferred reference, including their
published photometric errors. For the remaining objects, the UBVRI
magnitudes are from the latest Revised Bologna Catalogue of M31
Globular Clusters and candidates (Galleti et al., 2004, cat.
J/A+A/416/917; Galleti et al., 2006, cat. J/A+A/456/985; Galleti et
al., 2007, cat. J/A+A/471/127; Galleti et al., 2009, cat.
J/A+A/508/1285), with the photometric uncertainties set following
Galleti et al. (2004, cat. J/A+A/416/917), i.e., ±0.08mag in U and
±0.05mag in BVRI (Ma et al., 2009AJ....137.4884M 2009AJ....137.4884M).
Note (4): From Peacock et al (2010, cat. J/MNRAS/402/803).
Note (5): We preferentially adopted 2MASS JHKs magnitudes in the latest
Revised Bologna Catalogue of M31 Globular Clusters and candidates
(Galleti et al., 2004, cat. J/A+A/416/917; Galleti et al., 2006, cat.
J/A+A/456/985; Galleti et al., 2007, cat. J/A+A/471/127; Galleti et
al., 2009, cat. J/A+A/508/1285). For the remaining star clusters, we
adopted the r=4" aperture magnitudes in the 2MASS-6X Point Source
Catalog (cat. II/281) when the magnitudes are brighter than m=16mag
(see Section 2.4 for more details).
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Name Star cluster name
19- 23 F5.2 [yr] logA Log of the age
25- 28 F4.2 [yr] e_logA Uncertainty in logA
30- 33 F4.2 [Msun] logM ? Log of the mass
35- 38 F4.2 [Msun] e_logM ? Uncertainty in logM
40- 43 F4.2 mag E(B-V) The (B-V) color excess adopted
45- 48 F4.2 mag e_E(B-V) Uncertainty in E(B-V)
50 I1 --- r_E(B-V) Method for deriving E(B-V) (7)
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Note (7): Method as follows:
1 = E(B-V) was obtained by the first method in Kang et al. (2012,
cat J/ApJS/199/37);
2 = E(B-V) was obtained by the second method in Kang et al. (2012,
cat. J/ApJS/199/37);
3 = E(B-V) was from Caldwell et al. (2009, cat. J/AJ/137/94);
4 = E(B-V) was from Caldwell et al. (2011, cat. J/AJ/141/61).
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 13-Jan-2014