J/ApJ/527/199 HST observations of old clusters in the LMC (Johnson+, 1999)
Hubble space telescope observations of the oldest star clusters in the large
Magellanic cloud.
Johnson J.A., Bolte M., Stetson P.B., Hesser J.E., Somerville R.S.
<Astrophys. J. 527, 199 (1999)>
=1999ApJ...527..199J 1999ApJ...527..199J
ADC_Keywords: Clusters, globular ; HR diagrams ; Magellanic Clouds ; Photometry
Mission_Name: HST
Keywords: blue stragglers - globular clusters: individual (NGC 1466, i
NGC 2257, Hodge 11) - Magellanic Clouds
Abstract:
We present V, V-I color-magnitude diagrams (CMDs) for three old star
clusters in the Large Magellanic Cloud (LMC): NGC 1466, NGC 2257, and
Hodge 11. Our data extend ∼3 mag below the main-sequence turnoff,
allowing us to determine accurate relative ages and the blue straggler
frequencies. Based on a differential comparison of the CMDs, any age
difference between the three LMC clusters is less than 1.5 Gyr.
Comparing their CMDs to those of M92 and M3, the LMC clusters, unless
their published metallicities are significantly in error, are the same
age as the old Galactic globulars. The similar ages to Galactic
globulars are shown to be consistent with hierarchical clustering
models of galaxy formation. The blue straggler frequencies are also
similar to those of Galactic globular clusters. We derive a true
distance modulus to the LMC of (m - M)0 = 18.46 ± 0.09 [assuming
(m - M)0 = 14.61 for M92] using these three LMC clusters.
Objects:
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RA (2000) DE Designation(s)
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03 44 33 -71 40.3 NGC 1466 = ESO 54- 16
06 30 12 -64 19.6 NGC 2257 = ESO 87- 24
06 14 23 -69 50.8 Hodge 11 = Shapley-Lindsay 868
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2a.dat 49 17196 V and I photometry of NGC 1466
table2b.dat 49 15303 V and I photometry of NGC 2257
table2c.dat 49 17741 V and I photometry of Hodge 11
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See also:
J/MNRAS/300/665 : HST VI Photometry of Six LMC Old Globular Clusters
(Olsen+ 1998)
Byte-by-byte Description of file: table2*.dat
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Bytes Format Units Label Explanations
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1- 6 F6.2 pix Xpos X pixel position on Chip
9- 14 F6.2 pix Ypos Y pixel position on Chip
17- 22 F6.3 mag Vmag V band magnitude
25- 29 F5.3 mag e_Vmag Uncertainty in Vmag
33- 38 F6.3 mag V-I (V-I) color
41- 45 F5.3 mag e_V-I Uncertainty in V-I
49 I1 --- Chip Chip number (1 is the PC chip)
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History:
From ApJ electronic edition
(End) Greg Schwarz [AAS] 06-Mar-2000