J/AJ/116/723 LMC star clusters ages and metallicity (Bica+ 1998)
Ages and metallicities of star clusters and surrounding fields in the outer disk
of the Large Magellanic Cloud.
Bica E., Geisler D., Dottori H., Claria J.J., Piatti A.E.,
Santos J.F.C.Jr
<Astron. J. 116, 723 (1998)>
=1998AJ....116..723B 1998AJ....116..723B (SIMBAD/NED BibCode)
ADC_Keywords: Magellanic Clouds ; Abundances, [Fe/H] ; Photometry ;
Clusters, open
Keywords: galaxies: star clusters - Magellanic Clouds
Abstract:
We present Washington system CT1 color-magnitude diagrams of 13 star
clusters and their surrounding fields that lie in the outer parts of
the LMC disk (r>4°), as well as a comparison inner cluster. The
total area covered is large (2/3deg2), allowing us to study the
clusters and their fields individually and in the context of the
entire Galaxy. Ages are determined by means of the magnitude
difference δT1 between the giant branch clump and the turnoff,
while metallicities are derived from the location of the giant and
subgiant branches as compared with fiducial star clusters. This yields
a unique data set in which ages and metallicities for both a
significant sample of clusters and their fields are determined
homogeneously. We find that in most cases the stellar population of
each star cluster is quite similar to that of the field where it is
embedded, sharing its mean age and metallicity. The old population
(t≥10Gyr) is detected in most fields as a small concentration of
stars on the horizontal branch blueward and faintward of the prominent
clump.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tab134.dat 108 14 Sample of outlying clusters and surrounding
fields, ages, reddenings and metallicities
table2.dat 76 1788 Washington photometry
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Byte-by-byte Description of file: tab134.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Cluster Star cluster designation
14- 27 A14 --- OtherName Other name of the star cluster
30- 31 I2 h RAh Right ascension (B1950.0)
33- 34 I2 min RAm Right ascension (B1950.0)
36- 37 I2 s RAs Right ascension (B1950.0)
39 A1 --- DE- Declination sign
40- 41 I2 deg DEd Declination (B1950.0)
43- 44 I2 arcmin DEm Declination (B1950.0)
46- 47 I2 arcsec DEs Declination (B1950.0)
49- 53 F5.1 deg GLON Galactic longitude
55- 59 F5.1 deg GLAT Galactic latitude
61- 64 F4.1 deg Rad Cluster radius
66- 69 F4.1 deg R Deprojected angular distance
71 A1 --- Note [abc] Note (1)
73- 75 F3.1 Gyr AgeCluster Cluster age
76 A1 --- u_AgeCluster Uncertainty flag on AgeCluster
78 A1 --- l_AgeField Limit flag on AgeField
79- 81 F3.1 Gyr AgeField ? Field age
82 A1 --- n_AgeField [a] Note on AgeField (2)
84- 87 F4.2 mag E(B-V) Galactic reddening
89- 93 F5.2 [Sun] [Fe/H]C ? This paper cluster metallicity
94 A1 --- u_[Fe/H]C Uncertainty flag on [Fe/H]C
96-100 F5.2 [Sun] [Fe/H]O ? Olszewski et al. (1991AJ....101..515O 1991AJ....101..515O)
cluster metallicity
101 A1 --- u_[Fe/H]O Uncertainty flag on [Fe/H]O
103-107 F5.2 [Sun] [Fe/H]F ? Field metallicity
108 A1 --- u_[Fe/H]F Uncertainty flag on [Fe/H]F
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Note (1): the letter has the following meaning:
a: IC 2134 and SL 451 are located in the same frame
b: SL 769 is included for comparison purposes: its location
corresponds to the inner disk, i.e., in our definition when the
mean field turnoff becomes as bright as the clump.
This occurs at R∼4° (see text).
The younger field turnoff are younger than intermediate age (<1Gyr)
and outside of our age calibration.
c: The field population corresponds essentially to that of the Galaxy
Note (2): ameans that a significant fraction of younger stars is present.
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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- 12 A12 --- Cluster Cluster name
14- 18 I5 --- ID Identification number in the cluster
20- 28 F9.3 pix Xpos X position (1)
30- 37 F8.3 pix Ypos Y position (1)
39- 44 F6.3 mag T1 T1 magnitude
46- 50 F5.3 mag e_T1 rms uncertainty on T1
52- 57 F6.3 mag C-T1 C-T1 colour index
59- 63 F5.3 mag e_C-T1 rms uncertainty on C-T1
65- 69 F5.3 --- CHI χ PARAMETER
71- 76 F6.3 --- SHARP SHARP parameter
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Note (1): 1 pix = 0.40". North is up, east is to the left.
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History: From AJ electronic version
(End) James Marcout, Patricia Bauer [CDS] 05-Oct-1998