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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 (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:
FileName Lrecl Records Explanations
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
Byte-by-byte Description of file: tab134.dat
Bytes Format Units Label Explanations
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) 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
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.
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
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
Note (1): 1 pix = 0.40". North is up, east is to the left.
History: From AJ electronic version
(End) James Marcout, Patricia Bauer [CDS] 05-Oct-1998
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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