J/MNRAS/416/1077 Photometry of 3 open clusters (Cignoni+ 2011)
Three new bricks in the wall: Berkeley 23, Berkeley 31 and King 8.
Cignoni M., Beccari G., Bragaglia A., Tosi M.
<Mon. Not. R. Astron. Soc., 416, 1077-1091 (2011)>
=2011MNRAS.416.1077C 2011MNRAS.416.1077C
ADC_Keywords: Clusters, open ; Photometry, CCD
Keywords: Hertzsprung-Russell and colour-magnitude diagrams;
Galaxy: disc;
open clusters and associations: general;
open clusters and associations: individual: Berkeley 31;
open clusters and associations: individual: Berkeley 23;
open clusters and associations: individual: King 8
Abstract:
A comprehensive census of Galactic open cluster properties places
unique constraints on the Galactic disc structure and evolution. In
this framework, we investigate the evolutionary status of three poorly
studied open clusters, Berkeley 31, Berkeley 23 and King 8, all
located in the Galactic anticentre direction. To this aim, we make use
of deep Large Binocular Telescope observations, reaching more than
6mag below the main-sequence turn-off. To determine the cluster
parameters, namely age, metallicity, distance, reddening and binary
fraction, we compare the observational colour--magnitude diagrams
(CMDs) with a library of synthetic CMDs generated with different
evolutionary sets (Padova, FRANEC and FST) and metallicities. We find
that Berkeley 31 is relatively old, with an age between 2.3 and
2.9Gyr, and rather high above the Galactic plane, at about 700pc.
Berkeley 23 and King 8 are younger, with best-fitting ages in the
range 1.1-1.3 and 0.8-1.3 Gyr, respectively. The position above the
Galactic plane is about 500-600 pc for the former and 200 pc for the
latter. Although a spectroscopic confirmation is needed, our analysis
suggests a subsolar metallicity for all three clusters.
Based on observations collected at the Large Binocular Telescope (LBT)
and in part at the Italian Telescopio Nazionale Galileo (TNG). The LBT
is an international collaboration among institutions in the United
States, Italy and Germany. LBT Corporation partners are: The
University of Arizona on behalf of the Arizona University system;
Istituto Nazionale di Astrofisica, Italy; LBT
Beteiligungsgesellschaft, Germany, representing the Max-Planck
Society, the Astrophysical Institute Potsdam, and Heidelberg
University; The Ohio State University, and The Research Corporation,
on behalf of The University of Notre Dame, University of Minnesota and
University of Virginia. The TNG is operated on the island of La Palma
by the Fundacion Galileo Galilei of the INAF (Istituto Nazionale di
Astrofisica) at the Spanish Observatorio del Roque de los Muchachos of
the Instituto de Astrofisica de Canarias.
Description:
The three clusters were observed in service mode at the Large
Binocular Telescope (LBT) on Mt Graham (Arizona) with the Large
Binocular Camera (LBC) on 2008-Dec-02, and with the Device Optimized
for the LOw RESolution (DOLORES) at the Italian Telescopio Nazionale
Galileo (TNG) on 2009-Jan-03. There are two LBCs, one optimized for
the UV-blue filters and one for the red-IR ones, mounted at each prime
focus of the LBT. Each LBC uses four EEV chips (2048x4608 pixels)
placed three in a row and the fourth rotated 90° with respect
to the others. The field of view of the LBC is equivalent to 23x23
arcmin2, with a pixel sampling of 0.23 arcsec.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
be23.dat 88 6798 LBC photometric catalogue for open cluster Be 23
be31.dat 88 11752 LBC photometric catalogue for open cluster Be 31
king8.dat 88 7703 LBC photometric catalogue for open cluster King 8
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See also:
J/MNRAS/412/1265 : Photometry of 3 open clusters (Andreuzzi+, 2011)
Byte-by-byte Description of file: be23.dat be31.dat king8.dat
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Bytes Format Units Label Explanations
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3- 8 I6 --- ID Star identification number (1)
10- 20 F11.7 deg RAdeg Right Ascension in decimal degrees (J2000)
24- 34 F11.7 deg DEdeg Declination in decimal degrees (J2000)
38- 43 F6.3 mag Bmag The B band magnitude
48- 52 F5.3 mag e_Bmag The B band magnitude error (2)
56- 61 F6.3 mag Vmag The V band magnitude
66- 70 F5.3 mag e_Vmag The V band magnitude error (2)
73- 79 F7.4 --- chi2 DAOPHOT chi-square parameter
82- 88 F7.4 --- sharp DAOPHOT sharpness parameter (3)
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Note (1):
* ID values between 100001 and 199999 --> stars in CHIP1
* ID values between 200001 and 299999 --> stars in CHIP2
Note (2): magnitude errors are measured as standard deviation
of the mean of the independent measures
Note (3): the "sharp" parameter is close to zero for isolated stars;
significantly negative for bad pixels and cosmic rays;
significantly positive for blended or non-stellar objects.
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Acknowledgements:
Angela Bragaglia (angela.bragaglia(at)oabo.inaf.it)
(End) Francois Ochsenbein [CDS] 17-Feb-2012