J/A+A/561/A106 BV photometry of 6 SMC stellar clusters (Dias+, 2014)
Self-consistent physical parameters for 5 intermediate-age SMC stellar clusters
from CMD modelling.
Dias B., Kerber L., Barbuy B., Santiago B., Ortolani S., Balbinot E.
<Astron. Astrophys. 561, A106 (2014)>
=2014A&A...561A.106D 2014A&A...561A.106D
ADC_Keywords: Magellanic Clouds ; Associations, stellar ; Photometry, CCD ;
Photometry, UBV ; HR diagrams
Keywords: galaxies: star clusters - Magellanic Clouds -
Hertzsprung-Russell (HR) and C-M diagrams
Abstract:
Stellar clusters in the Small Magellanic Cloud (SMC) are useful probes
to study the chemical and dynamical evolution of this neighbouring
dwarf galaxy, enabling inspection of a large period covering over 10Gyr.
The main goals of this work are the derivation of age, metallicity,
distance modulus, reddening, core radius and central density profile
for six sample clusters, in order to place them in the context of the
Small Cloud evolution. The studied clusters are: AM 3, HW 1, HW 34, HW
40, Lindsay 2, and Lindsay 3, where HW 1, HW 34, and Lindsay 2 are
studied for the first time.
Optical Colour-Magnitude Diagrams (V, B-V CMDs) and radial density
profiles were built from images obtained with the 4.1m SOAR telescope,
reaching V∼23. The determination of structural parameters were carried
out applying King profile fitting. The other parameters were derived
in a self-consistent way by means of isochrone fitting, which uses the
likelihood statistics to identify the synthetic CMDs that best
reproduce the observed ones. Membership probabilities were determined
comparing the cluster and control field CMDs. Completeness and
photometric uncertainties were obtained performing artificial star
tests.
The results confirm that these clusters (except HW 34, identified as a
field fluctuation) are intermediate-age clusters, with ages between
1.2Gyr (Lindsay 3) and ∼5.0Gyr (HW 1). In particular HW 1, Lindsay 2,
and Lindsay 3 are located in a region that we called West Halo, where
studies on ages and metallicity gradients are still lacking. Moreover
Lindsay 2 was identified as a moderately metal-poor cluster with
[Fe/H]=-1.4±0.2dex, lower than expected from the age-metallicity
relation by Pagel & Tautvaisiene (1998MNRAS.299..535P 1998MNRAS.299..535P). We also found
distances varying from ∼53 to 66kpc, compatible with the large depth
of the SMC.
Description:
Photometric magnitudes from SOAR Optical Imager for individual stars
in 6 stellar clusters in the Small Magellanic Cloud are presented. The
following clusters are presented: AM3, HW1, HW34, HW40, Lindsay2, and
Linsday3. For each star equatorial coordinates, B and V (Bessel)
magnitudes, completeness and cluster membership probability are given.
Completeness for each star is an interpolation of completeness curves
as a function of distance to cluster center and magnitude. Membership
probability is given only for stars within a radius of 90 arcsec from
the cluster center (see paper).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 79 6 Log of observations
am3.dat 89 252 Star coordinates, magnitudes, completeness and
membership probability for AM3
hw1.dat 89 2309 Star coordinates, magnitudes, completeness and
membership probability for HW1
hw34.dat 89 5457 Star coordinates, magnitudes, completeness and
membership probability for HW34
hw40.dat 89 2667 Star coordinates, magnitudes, completeness and
membership probability for HW40
l2.dat 89 1334 Star coordinates, magnitudes, completeness and
membership probability for Lindsay2
l3.dat 89 2019 Star coordinates, magnitudes, completeness and
membership probability for Lindsay3
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See also:
J/MNRAS/377/300 : CT1 photometry in 6 SMC star clusters (Piatti+, 2007)
J/MNRAS/381/L84 : CT1 photometry of 3 SMC old clusters (Piatti+, 2007)
J/MNRAS/382/1203 : CT1 photometry of 5 SMC star clusters (Piatti+, 2007)
J/MNRAS/389/429 : CT1 photometry of 7 young SMC star clusters (Piatti+, 2008)
J/MNRAS/417/1559 : CT1T2 photometry in 14 SMC star clusters (Piatti+, 2011)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 "YYYY-MM-DD" Date Observation date
12- 20 A9 --- Cluster Cluster name
22- 23 I2 h RAh Right ascension (J2000)
25- 26 I2 min RAm Right ascension (J2000)
28- 29 I2 s RAs Right ascension (J2000)
31 A1 --- DE- Declination sign (J2000)
32- 33 I2 deg DEd Declination (J2000)
35- 38 F4.1 arcmin DEm Declination (J2000)
40 A1 --- --- [B]
42- 44 I3 s Bexp Exposure time in B band
46- 49 F4.2 --- BairM Airmass in B band
51- 54 F4.2 arcsec Bsee Seeing in B band
56 A1 --- --- [V]
58- 60 I3 s Vexp Exposure time in V band
62- 65 F4.2 --- VairM Airmass in V band
67- 70 F4.2 arcsec Vsee Seeing in V band
72- 79 A8 --- FileName Name of the file with photometry
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Byte-by-byte Description of file: [ahl]*.dat
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Bytes Format Units Label Explanations
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1- 2 I2 h RAh Right ascension (J2000.0)
4- 5 I2 min RAm Right ascension (J2000.0)
7- 11 F5.2 s RAs Right ascension (J2000.0)
14 A1 --- DE- Declination sign (J2000.0)
15- 16 I2 deg DEd Declination (J2000.0)
18- 19 I2 arcmin DEm Declination (J2000.0)
21- 25 F5.2 arcsec DEs Declination (J2000.0)
28- 36 F9.5 deg RAdeg Right ascension in decimal degrees (J2000.0)
38- 46 F9.5 deg DEdeg Declination in decimal degrees (J2000.0)
49- 54 F6.3 mag Bmag B-Bessel magnitude
56- 60 F5.3 mag e_Bmag Error in B-Bessel magnitude
63- 68 F6.3 mag Vmag V-Bessel magnitude
70- 74 F5.3 mag e_Vmag Error in V-Bessel magnitude
77- 82 F6.4 --- Cmpl Completeness (1)
84- 89 F6.3 --- Pmem [0/1]? Cluster membership probability (2)
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Note (1): Completeness for each star is an interpolation of completeness curves
as a function of distance to cluster center and magnitude (see paper).
Note (2): Pmem is only provided for stars within 90 arcsec from the cluster
center, considered as a boundary for cluster stars (see paper).
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Acknowledgements:
Leandro Kerber, lekerber(at)gmail.com
(End) Bruno Dias [IAG/USP, Brazil], Patricia Vannier [CDS] 06-Dec-2013