J/MNRAS/384/1444 Vr light curves of NGC 5466 RR Lyrae (Arellano Ferro+, 2008)
CCD Photometry of the globular cluster NGC 5466. RR Lyrae light curve
decomposition and the distance scale.
Arellano Ferro A., Rojas Lopez V., Giridhar S., Bramich D.M.
<Mon. Not. R. Astron. Soc. 384, 1444 (2008)>
=2008MNRAS.384.1444A 2008MNRAS.384.1444A
ADC_Keywords: Clusters, globular ; Stars, variable ; Photometry, CCD
Keywords: globular clusters: NGC 5466 - variable stars: RR Lyrae, SX Phe -
eclipsing binaries
Abstract:
We report the results of CCD V and r photometry of the globular
cluster NGC 5466. The difference image analysis technique adopted in
this work has resulted in accurate time series photometry even in
crowded regions of the cluster enabling us to discover five probably
semi-regular variables. We present new photometry of three previously
known eclipsing binaries and six SX Phe stars.
The light curves of the RR Lyrae stars have been decomposed in their
Fourier harmonics and their fundamental physical parameters have been
estimated using semi-empirical calibrations. The zero points of the
metallicity, luminosity and temperature scales are discussed and our
Fourier results are transformed accordingly.
The average iron abundance and distance to the Sun derived from
individual RR Lyrae stars, indicate values of [Fe/H]=-1.91±0.19 and
D=16.0±0.6kpc, or a true distance modulus of 16.02±0.09mag, for
the parent cluster. These values are respectively in the Zinn & West
metallicity scale and in agreement with recent luminosity
determinations for the RR Lyrae stars in the LMC.
The MV-[Fe/H] relation has been recalibrated as
MV=+(0.18±0.03)[Fe/H]+(0.85±0.05) using the mean values derived
by the Fourier technique on RR Lyrae s tars in a family of clusters.
This equation predicts MV=0.58mag for [Fe/H]=-1.5, in agreement with
the average absolute magnitude of RR Lyrae stars calculated from
several independent methods. The M_V-[Fe/H] relationship and the
value of [Fe/H] have implications on the age of the globular clusters
when determined from the magnitude difference between the horizontal
branch and the turn off point (HB-TO method). The above results
however would not imply a change in the age of NGC 5466, of
12.5±0.9Gyr, estimated from recent isochrone fitting.
Objects:
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RA (2000) DE Designation(s)
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14 05 27.4 +28 32 04 NGC 5466 = C 1403+287
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 99 35 Star list and ephemerides of the known RR Lyrae
table3.dat 30 2035 Standard V magnitudes of RR Lyrae stars in NGC 5466
table4.dat 30 1998 Instrumental r magnitudes of RR Lyrae stars
table5.dat 30 462 Standard V magnitudes of new variables in NGC 5466
table6.dat 30 896 Standard V magnitudes of 3 eclipsing binaries
and 6 SX Phoenicis stars
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See also:
V/97 : Updated 3rd Cat Variable Stars in Globular Clusters (Clement+ 1997)
Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Star Variable name
6- 25 A20 --- SName Simbad name (if exist)
27- 35 F9.7 d Per ? Period
37 I1 --- r_Per [1/4]? Period reference (1)
39- 49 F11.3 d Epoch ? Epoch
51- 58 F8.6 d PerN ? New period
60- 70 F11.3 d EpochN ? New epoch
72- 95 A24 --- VType Type of variable
97- 99 A3 --- Tables Number of the table(s) with photometry
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Note (1): Period reference as follows:
1 = Sawyer Hogg, 1973PDDO....3....6S 1973PDDO....3....6S (See Cat. V/97
2 = Corwin et al., 1999AJ....118.2875C 1999AJ....118.2875C
3 = McCarthy & Nemec, 1997ApJ...482..203M 1997ApJ...482..203M
4 = this paper
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Byte-by-byte Description of file: table*.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Star Variable number identification
6- 17 F12.4 d HJD Heliocentric Julian Date
21 A1 --- Band [Vr] Band for the magnitude
25- 30 F6.3 mag mag Standard V or r magnitude
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Acknowledgements:
Armando Arellano Ferro, armando(at)astroscu.unam.mx
(End) Patricia Vannier [CDS] 05-Mar-2008