J/MNRAS/434/2438 NGC 1960 (RI)c photometric catalogue (Jeffries+, 2013)
A lithium depletion boundary age of 22Myr for NGC 1960.
Jeffries R.D., Naylor T., Mayne N.J., Bell C.P.M., Littlefair S.P.
<Mon. Not. R. Astron. Soc., 434, 2438-2450 (2013)>
=2013MNRAS.434.2438J 2013MNRAS.434.2438J
ADC_Keywords: Clusters, open ; Photometry, Cousins
Keywords: stars: pre-main-sequence -
open clusters and associations: individual: NGC 1960
Abstract:
We present a deep Cousins RI photometric survey of the open cluster
NGC 1960, complete to RC≃22, IC≃21, that is used to select a
sample of very low mass cluster candidates. Gemini spectroscopy of a
subset of these is used to confirm membership and locate the
age-dependent 'lithium depletion boundary' (LDB) - the luminosity at
which lithium remains unburned in its low-mass stars. The LDB implies
a cluster age of 22±4Myr and is quite insensitive to choice of
evolutionary model. NGC 1960 is the youngest cluster for which a LDB
age has been estimated and possesses a well-populated upper main
sequence and a rich low-mass pre-main sequence. The LDB age determined
here agrees well with precise age estimates made for the same cluster
based on isochrone fits to its high- and low-mass populations. The
concordance between these three age estimation techniques, that rely
on different facets of stellar astrophysics at very different masses,
is an important step towards calibrating the absolute ages of young
open clusters and lends confidence to ages determined using any one of
them.
Description:
In order to select faint, low-mass targets for subsequent
spectroscopy, a photometric survey of NGC 1960 was performed using the
Wide Field Camera (WFC) at the Isaac Newton Telescope (INT) on La
Palma on the night of the 2004 September 28. The WFC consists of four
thinned EEV 2kx4k CCDs (numbered 1-4) covering 0.33-arcsec/pix on the
sky.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 88 30857 The Ic vs Rc-Ic photometric catalogue
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See also:
J/A+A/357/471 : BV and proper motions in NGC1960 + NGC2194 (Sanner+, 2000)
J/MNRAS/420/2884 : NGC 1960 IRAC and MIPS photometry (Smith+, 2012)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 F4.2 --- F [1.01/1.04] Field and CCD designation (F.NN)
6- 10 I5 --- Star [2/11192] Star identification in CCD
(only one field was observed)
12- 13 I2 h RAh Right ascension (J2000)
15- 16 I2 min RAm Right ascension (J2000)
18- 23 F6.3 s RAs Right ascension (J2000)
25 A1 --- DE- Declination sign (J2000)
26- 27 I2 deg DEd Declination (J2000)
29- 30 I2 arcmin DEm Declination (J2000)
32- 36 F5.2 arcsec DEs Declination (J2000)
38- 45 F8.3 pix Xpos CCD X position
47- 54 F8.3 pix Ypos CCD Y position
56- 61 F6.3 mag Icmag Cousins I magnitude
63- 68 F6.3 mag e_Icmag rms uncertainty on Icmag
70- 71 A2 --- f_Icmag Flag on Icmag (1)
73- 78 F6.3 mag Rc-Ic Cousins R-I colour index
80- 85 F6.3 mag e_Rc-Ic rms uncertainty on Rc-Ic
87- 88 A2 --- f_Rc-Ic Flag on Rc-Ic (1)
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Note (1): OO for a "clean", unflagged detection.
Detailed description of the flags given by Burningham et al.
(2003MNRAS.346.1143B 2003MNRAS.346.1143B, Cat. J/MNRAS/346/1143) as follows:
O: O.K.
N: Non-stellar
E: Too close to CCD edge
B: Background fit failed
I: Ill-determined background
P: Position fit failed
S: Saturated
E: Too close to edge
F: Flagged pixel
R: Uncalibrated region
A: Absent input data
M: Negative (minus) counts
V: Variable
C: Large relative transparency correction (cloudy)
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 11-Sep-2014