J/AJ/146/57 NGC 6402. I. BV photometry (Contreras Pena+, 2013)
The globular cluster NGC 6402 (M14). I. A new BV color-magnitude diagram.
Contreras Pena C., Catelan M., Grundahl F., Stephens A.W., Smith H.A.
<Astron. J., 146, 57 (2013)>
=2013AJ....146...57C 2013AJ....146...57C
ADC_Keywords: Clusters, globular ; Photometry, UBV ; Stars, variable
Keywords: galaxies: dwarf - galaxies: star clusters: general -
globular clusters: individual: NGC 6402 -
Hertzsprung-Russell and C-M diagrams - stars: variables: general
Abstract:
We present BV photometry of the Galactic globular cluster NGC 6402
(M14), based on 65 V frames and 67 B frames, reaching two magnitudes
below the turnoff level. This represents, to the best of our
knowledge, the deepest color-magnitude diagram (CMD) of NGC 6402
available in the literature. Statistical decontamination of field
stars as well as differential reddening corrections are performed in
order to derive a precise ridgeline and hence physical parameters of
the cluster. We discuss previous attempts at deriving a reddening
value for the cluster, and argue in favor of a value
E(B-V)=0.57±0.02, which is significantly higher than indicated by
either the Burstein & Heiles or Schlegel et al. (corrected according
to Bonifacio et al.) interstellar dust maps. Differential reddening
across the face of the cluster, which we find to be present at the
level of ΔE(B-V)~0.17mag, is taken into account in our
analysis. We measure several metallicity indicators based on the
position of the red giant branch (RGB) in the cluster CMD. These give
a metallicity of [Fe/H]=-1.38±0.07 on the Zinn & West scale and
[Fe/H]=-1.28±0.08 on the new Carretta et al. (UVES) scale. We also
provide measurements of other important photometric parameters for
this cluster, including the position of the RGB luminosity function
"bump" and the horizontal branch morphology. We compare the NGC 6402
ridgeline with that of NGC 5904 (M5) derived by Sandquist et al., and
find evidence that NGC 6402 and M5 have approximately the same age to
within the uncertainties, although the possibility that M14 may be
slightly older cannot be ruled out.
Description:
Time-series B, V, and I photometry was obtained with the 0.9m
telescope at the Cerro Tololo Inter-American Observatory (CTIO;
operated by the SMARTS consortium), Chile, during 16 nights between
2007 June 22 and July 12, comprising a total of 67, 65, and 62 images
in B, V, and I, respectively.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 65 8126 BV photometry for M14
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See also:
J/AJ/140/1766 : RR Lyrae in M62 (NGC6266) (Contreras+, 2010)
J/AJ/139/357 : Variable stars in NGC 5286 (Zorotovic+, 2010)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- --- [ID-]
4- 7 I4 --- Star [1/8126] Running star number
<[CCG2013] ID-NNNN> in Simbad
9- 10 I2 h RAh Hour of Right Ascension (J2000)
12- 13 I2 min RAm Minute of Right Ascension (J2000)
15- 19 F5.2 s RAs Second of Right Ascension (J2000)
22 A1 --- DE- Sign of the Declination (J2000)
23 I1 deg DEd Degree of Declination (J2000)
25- 26 I2 arcmin DEm Arcminute of Declination (J2000)
28- 32 F5.2 arcsec DEs Arcsecond of Declination (J2000)
34- 39 F6.3 mag Bmag [14.2/23.5] The B band magnitude
41- 45 F5.3 mag e_Bmag [0.001/0.06] Error in Bmag
47- 52 F6.3 mag Vmag [13.26/22.51] The V band magnitude
54- 58 F5.3 mag e_Vmag [0.001/0.06] Error in Vmag
60- 65 F6.3 mag E(B-V) [-0.08/0.12] Differential reddening ΔE(B-V)
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History:
From electronic version of the journal
References:
Contreras Pena et al., Paper II, 2018AJ....155..116C 2018AJ....155..116C
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 03-Jul-2014