J/MNRAS/386/1625 Velocities and photometry in NGC 2112 (Carraro+, 2008)
The old open cluster NGC 2112: updated estimates of fundamental parameters based
on a membership analysis.
Carraro G., Villanova S., Demarque P., Bidin C.M., McSwain M.V.
<Mon. Not. R. Astron. Soc., 386, 1625-1634 (2008)>
=2008MNRAS.386.1625C 2008MNRAS.386.1625C
ADC_Keywords: Clusters, open ; Photometry, UBVRI ; Radial velocities ;
Proper motions
Keywords: open clusters and associations: general -
open clusters and associations: individual: NGC 2112
Abstract:
We report on a new, wide-field (20x20arcmin2), multicolour (UBVI),
photometric campaign in the area of the nearby old open cluster NGC
2112. At the same time, we provide medium-resolution spectroscopy of
35 (and high-resolution of additional 5) red giant and turn-off stars.
This material is analysed with the aim to update the fundamental
parameters of this traditionally difficult cluster, which is very
sparse and suffers from heavy field star contamination. Among the 40
stars with spectra, we identified 21 bona fide radial velocity members
which allow us to put more solid constraints on the cluster's metal
abundance, long suggested to be as low as the metallicity of
globulars. As indicated earlier by us on a purely photometric basis,
the cluster [Fe/H] abundance is slightly supersolar
([Fe/H]=0.16±0.03) and close to the Hyades value, as inferred from a
detailed abundance analysis of three of the five stars with higher
resolution spectra. Abundance ratios are also marginally supersolar.
Based on this result, we revise the properties of NGC 2112 using
stellar models from the Padova and Yale-Yonsei groups.
Description:
U, B, V and I images centred on NGC 2112 were obtained at the Cerro
Tololo Inter-American Observatory 1.0-m telescope, which is operated
by the SMARTS1 consortium. The telescope is equipped with a new
4000x4000 CCD camera having a pixel scale of 0.289arcsec/pixel, which
allows one to cover a field of 20x20arcmin2. This allows us to cover
the entire cluster, which has an estimated diameter of 18 arcmin (Dias
et al., 2002, Cat. VII/229).
Observations were carried out on 2005 November 30.
Medium-resolution spectroscopic observations were carried out on the
night of 2006 February 15 (Julian Date 2453783.57006) with the Hydra
spectrograph onboard the Wisconsin Indiana Yale NOAO (WIYN) telescope
at Kitt Peak National Observatory
Echelle spectrograms of stars 535, 261, 717, 304 and 836 were obtained
on 2007 October 29 with the Magellan Inamori Kyocera Echelle (MIKE)
spectrograph mounted on the Nasmyth focus of Landon Clay 6.5-m
telescope at the Magellan Observatory. Data were obtained with both
the blue and red arms.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 102 40 Basic properties of the stars for which we
secured spectroscopic observations
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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- 5 A5 --- Inst Instrument used (1)
7- 10 I4 --- Seq Sequential number,
Cl* NGC 2112 CVD NNNN in Simbad
12- 13 I2 h RAh Right ascension (J2000)
15- 16 I2 min RAm Right ascension (J2000)
18- 21 F4.1 s RAs Right ascension (J2000)
23 A1 --- DE- Declination sign (J2000)
24- 25 I2 deg DEd Declination (J2000)
27- 28 I2 arcmin DEm Declination (J2000)
30- 33 F4.1 arcsec DEs Declination (J2000)
35- 40 F6.3 mag Umag ? Johnson U magnitude
42- 47 F6.3 mag Bmag Johnson B magnitude
49- 54 F6.3 mag Vmag ? Johnson V magnitude
56- 60 F5.3 mag e_Vmag ? rms uncertainty on Vmag
62- 67 F6.3 mag Icmag ? Cousins I magnitude
69- 74 F6.2 km/s HRV Heliocentric radial velocity
76- 79 F4.2 km/s e_HRV rms uncertainty on HRV
81- 85 F5.1 mas/yr pmRA ? Proper motion along RA (pmRA*cosDE)
87- 89 F3.1 mas/yr e_pmRA ? rms uncertainty on pmRA
91- 95 F5.1 mas/yr pmDE ? Proper motion along DE
97- 99 F3.1 mas/yr e_pmDE ? rms uncertainty on pmDE
101-102 A2 --- Mm [M NM] Membership according to radial velocity
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Note (1): Instruments as follows:
Hydra = Hydra spectrograph
MIKE = Magellan Inamori Kyocera Echelle spectrograph
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 12-Jun-2009