J/MNRAS/376/580 Cousins RI photometry of NGC 2169 (Jeffries+, 2007)
The Keele-Exeter young cluster survey -
I. Low-mass pre-main-sequence stars in NGC 2169.
Jeffries R.D., Oliveira J.M., Naylor T., Mayne N.J., Littlefair S.P.
<Mon. Not. R. Astron. Soc., 376, 580-598 (2007)>
=2007MNRAS.376..580J 2007MNRAS.376..580J
ADC_Keywords: Clusters, open ; Stars, pre-main sequence ; Photometry, Cousins
Keywords: stars: abundances - stars: late-type - stars: pre-main sequence -
open clusters and associations: individual: NGC 2169
Abstract:
We have used Cousins RI CCD photometry from the Isaac Newton telescope
and intermediate-resolution spectroscopy from the Gemini North
telescope to identify and characterize low-mass (0.15<M/M☉<1.3)
pre-main-sequence stars in the young open cluster NGC 2169. Isochrone
fitting to the high- and low-mass populations yields an intrinsic
distance modulus of 10.13+0.06-0.09mag and a model-dependent age
of 9±2Myr. Compared to the nearby, kinematically defined groups of a
similar age, NGC 2169 has a large low-mass population which
potentially offers a more precise statistical investigation of several
aspects of star formation and early stellar evolution. By modelling
the distribution of low-mass stars in the IC versus RC IC diagram, we
find that any age spread among cluster members has a Gaussian full
width at half-maximum (FWHM) 2.5Myr. A young age and a small age
spread (<10Myr) are supported by the lack of significant lithium
depletion in the vast majority of cluster members. There is no clear
evidence for accretion or warm circumstellar dust in the low-mass
members of NGC 2169, bolstering the idea that strong accretion has
ceased and inner discs have dispersed in almost all low-mass stars by
ages of 10Myr.
Description:
We observed NGC 2169 on the night beginning 2004 September 28, using
the Wide-Field Camera (WFC) on the 2.5-m Isaac Newton telescope (INT).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 86 27131 NGC 2169 Rc versus Rc-Ic photometric catalogue
table5.dat 67 48 Identification (as given in Table 3) positions
and photometry for the 47 targets observed in
three separate GMOS masks
table6.dat 48 48 Results from the spectral analysis of Section 4.2,
listing spectral type, estimated S/N, EWs of the
LiI 6708Å and Hα lines and HRV
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 F4.2 --- Field Field designation
6- 10 I5 --- Star Star number in the field
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 [0/60] Declination (J2000)
38- 45 F8.3 pix Xpos X position
47- 54 F8.3 pix Ypos Y position
56- 61 F6.3 mag Icmag ? Cousins I magnitude
63- 67 F5.3 mag e_Icmag ? rms uncertainty on Icmag
69- 70 A2 --- f_Icmag Flag for Icmag (1)
72- 77 F6.3 mag Rc-Ic ? Cousins R-I colour index
79- 83 F5.3 mag e_Rc-Ic ? rms uncertainty on Rc-Ic
85- 86 A2 --- f_Rc-Ic Flag for Rc and Ic (1)
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Note (1): Quality flags are:
O = O.K.
N = Non-stellar
H = Aperture photometry used
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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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1 I1 --- Mask [1/3] Mask number
3- 4 I2 --- Target Target number
6- 9 F4.2 --- Field Field designation
11- 15 I5 --- Star Star number in the field
17- 18 I2 h RAh ? Right ascension (J2000)
20- 21 I2 min RAm ? Right ascension (J2000)
23- 28 F6.3 s RAs ? Right ascension (J2000)
30 A1 --- DE- Declination sign (J2000)
31- 32 I2 deg DEd ? Declination (J2000)
34- 35 I2 arcmin DEm ? Declination (J2000)
37- 41 F5.2 arcsec DEs ? Declination (J2000)
43- 48 F6.3 mag Icmag ? Cousins I magnitude
50- 54 F5.3 mag e_Icmag ? rms uncertainty on Icmag
56- 60 F5.3 mag Rc-Ic ? Cousins R-I colour index
62- 66 F5.3 mag e_Rc-Ic ? rms uncertainty on Rc-Ic
67 A1 --- Note [a] a: Repeated in this mask
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1 I1 --- Mask [1/3] Mask number
3- 4 I2 --- Target Target number
6- 9 A4 --- SpType Photometric spectral type
11- 13 I3 --- S/N Signal-to-noise ratio
15 A1 --- l_EW(Li) Limit flag on EW(Li)
16- 19 F4.2 0.1nm EW(Li) ?=- Li Equivalent width
21- 24 F4.2 0.1nm e_EW(Li) ?=- rms uncertainty on EW(Li)
26- 29 F4.2 0.1nm FWHM(Li) ?=- Li FWHM
31- 35 F5.1 0.1nm EW(Ha) ?=- Hα Equivalent width
37- 41 F5.1 km/s RV Radial velocity
43- 46 F4.1 km/s e_RV rms uncertainty on RV
48 A1 --- Mm Membership flag (1)
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Note (1): Membership flag as follows:
Y = member
N = non-member
? = membership questionable
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 17-Sep-2007