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J/AJ/117/2244   HST color-magnitude diagrams of the LMC    (Olsen, 1999)

Star formation histories from Hubble space telescope color-magnitude diagrams of six fields of the Large Magellanic Cloud Olsen K.A.G. <Astron. J. 117, 2244 (1999)> =1999AJ....117.2244O
ADC_Keywords: Clusters, globular ; HR diagrams ; Magellanic Clouds ; Photometry Mission_Name: HST Keywords: galaxies: evolution - galaxies: stellar content - Magellanic Clouds - stars: formation Abstract: We present results on the analysis of background field stars found in Hubble Space Telescope Wide Field Planetary Camera 2 observations of six of the old globular clusters of the Large Magellanic Cloud. Treated as contaminants by the globular cluster analysts, we produce (V-I, V) color-magnitude diagrams (CMDs) of the field stars and use them to explore the LMC's star formation history. The photometry approaches V ∼ 26, well below the turnoff of an ancient (∼ 14 Gyr) LMC population of stars. The field star CMDs are generally characterized by an upper main sequence broadened by stellar evolution, an old red giant branch, a prominent red clump, and an unevolved lower main sequence. The CMDs also contain a few visual differences, the most obvious of which is the smeared appearance of the NGC 1916 field caused by heavy differential reddening. More subtly, the base of the subgiant branch near the old turnoff appears extended in V, and the red giant branch appears broad in V-I in four of the fields but not in the NGC 1754 field. Description: Observations of the six LMC globular clusters NGC 1754, 1835, 1898, 1916, 2005, and 2019 were taken during Cycle 5 of HST using the Wide Field Planetary Camera 2 (WFPC2) and the F555W and F814W filters. By taking both long and short exposures through each filter, we were ensured reliable photometry of the brightest stars in the fields while still reaching V ≥ 25. We centered the clusters on the Planetary Camera leaving the Wide Field (WF) chips containing primarily field stars. Objects: ----------------------------------------- RA (2000) DE Designation(s) ----------------------------------------- 04 54 17 -70 26.5 NGC 1754 05 05 11 -69 24.5 NGC 1835 05 16 43 -69 39.9 NGC 1898 05 18 39 -69 24.9 NGC 1916 05 30 15 -69 45.5 NGC 2005 05 32 02 -70 09.9 NGC 2019 ----------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1a.dat 75 10787 NGC 1754 Wide Field Camera photometry table1b.dat 75 27047 NGC 1835 Wide Field Camera photometry table1c.dat 75 28568 NGC 1898 Wide Field Camera photometry table1d.dat 75 29144 NGC 1916 Wide Field Camera photometry table1e.dat 75 29156 NGC 2005 Wide Field Camera photometry table1f.dat 75 29144 NGC 2019 Wide Field Camera photometry
See also: J/MNRAS/300/665 : HST VI Photometry of Six LMC Old Globular Clusters (Olsen+ 1998) Byte-by-byte Description of file: table1*.dat
Bytes Format Units Label Explanations
1- 5 I5 --- Star Star number 8- 13 F6.2 pix Xpix X pixel value in the V band image 16- 21 F6.2 pix Ypix Y pixel value in the V band image 25- 31 F7.4 mag Vmag Johnson V band magnitude 36- 41 F6.4 mag e_Vmag Uncertainty in Vmag from DaoPHOT 45- 51 F7.4 mag Imag Cousins I band magnitude 56- 61 F6.4 mag e_Imag Uncertainty in Imag from DaoPHOT 65- 66 I2 --- VType DaoPHOT object type (1) 70- 71 I2 --- IType DaoPHOT object type (1) 75 A1 --- f_Star [y] Stars removed by cluster-star cleaning procedure
Note (1): The DaoPHOT object type is: 1 = perfect star 2 = galaxy 3 = member of overlapping stellar group 7 = faint but measurable object Where the short-exposure photometry was used, the DoPHOT object type has been multiplied by 10.
History: From AJ electronic edition
(End) Greg Schwarz [AAS] 11-Apr-2000
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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