J/AJ/144/100 CCD Washington CT1T2 photometry of stars in LMC (Piatti+, 2012)
A Washington photometric survey of the Large Magellanic Cloud field star
population.
Piatti A.E., Geisler D., Mateluna R.
<Astron. J., 144, 100 (2012)>
=2012AJ....144..100P 2012AJ....144..100P
ADC_Keywords: Magellanic Clouds ; Associations, stellar ; Photometry, CMT1T2V
Keywords: Magellanic Clouds - galaxies: individual (LMC) -
galaxies: star clusters: general - techniques: photometric
Abstract:
We present photometry for an unprecedented database of some 5.5million
stars distributed throughout the Large Magellanic Cloud main body,
from 21 fields covering a total area of 7.6deg2, obtained from
Washington CT1T2 CTIO 4m MOSAIC data. Extensive artificial star
tests over the whole mosaic image data set and the observed behavior
of the photometric errors with magnitude demonstrate the accuracy of
the morphology and clearly delineate the position of the main features
in the color-magnitude diagrams (CMDs). The representative T1(MS TO)
mags are on average ∼0.5mag brighter than the T1 mags for the 100%
completeness level of the respective field, allowing us to derive an
accurate age estimate. We have analyzed the CMD Hess diagrams and used
the peaks in star counts at the main sequence turnoff and red clump
(RC) locations to age date the most dominant sub-population (or
"representative" population) in the stellar population mix. The
metallicity of this representative population is estimated from the
locus of the most populous red giant branch track. We use these
results to derive age and metallicity estimates for all of our fields.
The analyzed fields span age and metallicity ranges covering most of
the galaxy's lifetime and chemical enrichment, i.e., ages and
metallicities between ∼1 and 13Gyr and ~-0.2 and -1.2dex,
respectively. We show that the dispersions associated with the mean
ages and metallicities represent in general a satisfactory estimate of
the age/metallicity spread (∼1-3 Gyr/0.2-0.3 dex), although a few
subfields have a slightly larger age/metallicity spread. Finally, we
revisit the study of the vertical structure (VS) phenomenon, a
striking feature composed of stars that extend from the bottom, bluest
end of the RC to ∼0.45mag fainter. We confirm that the VS phenomenon
is not clearly seen in most of the studied fields and suggest that its
occurrence is linked to some other condition(s) in addition to the
appropriate age, metallicity, and the necessary red giant star
density.
Description:
We obtained images at the Cerro-Tololo Inter-American Observatory
(CTIO) 4m Blanco telescope on 2008 Dec 18-20 with the Mosaic II camera
(36'*36' field with an 8K*8K CCD detector array) covering 21 fields of
the LMC main body for a total area of ∼7.6deg2. The field 1 (table2)
was observed on 2008-12-20.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 63 21133 CT1T2 data of stars in the Field 1
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See also:
II/236 : UBVR CCD survey of the Magellanic clouds (Massey+, 2002)
II/232 : UBV photometry of selected regions in the MCs (Braun 2001)
II/228 : DENIS Catalogue toward Magellanic Clouds (DCMC) (Cioni+ 2000)
VII/183 : The Cluster System of the LMC (Kontizas+ 1990)
J/MNRAS/425/3085 : CCD CT1 data of stars in the field of B119 (Piatti+, 2012)
J/MNRAS/417/1559 : CT1T2 photometry in 14 SMC star clusters (Piatti+, 2011)
J/PASP/123/519 : C,T1 photometry of 6 LMC clusters (Piatti+, 2011)
J/A+A/501/585 : CT1 photometry in five LMC star clusters (Piatti+, 2009)
J/AJ/138/1243 : The star formation history of the LMC (Harris+, 2009)
J/MNRAS/377/300 : CT1 photometry in 6 SMC star clusters (Piatti+, 2007)
J/AJ/117/238 : LMC extended catalog (Bica+, 1999)
J/AJ/116/723 : LMC star clusters ages and metallicity (Bica+ 1998)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Seq Running sequence number
7- 14 F8.5 deg RAdeg Right Ascension in decimal degrees (J2000)
16- 24 F9.5 deg DEdeg Declination in decimal degrees (J2000)
26- 31 F6.3 mag T1mag The Washington T1 band magnitude
33- 37 F5.3 mag e_T1mag Uncertainty in T1
39- 44 F6.3 mag C-T1 The Washington (C-T1) color index
46- 50 F5.3 mag e_C-T1 Uncertainty in C-T1
52- 57 F6.3 mag T1-T2 The Washington (T1-T2) color index
59- 63 F5.3 mag e_T1-T2 Uncertainty in T1-T2
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 23-Oct-2013