J/ApJ/795/22 Iron abundance of Terzan 5 stars (Massari+, 2014)
Ceci n'est pas a globular cluster: the metallicity distribution of
the stellar system Terzan 5.
Massari D., Mucciarelli A., Ferraro F.R., Origlia L., Rich R.M.,
Lanzoni B., Dalessandro E., Valenti E., Ibata R., Lovisi L., Bellazzini M.,
Reitzel D.
<Astrophys. J., 795, 22 (2014)>
=2014ApJ...795...22M 2014ApJ...795...22M (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Milky Way ; Magnitudes ;
Effective temperatures ; Abundances, [Fe/H]
Keywords: globular clusters: individual: Terzan 5 - stars: abundances -
techniques: spectroscopic
Abstract:
We present new determinations of the iron abundance for 220 stars
belonging to the stellar system Terzan 5 in the Galactic bulge. The
spectra have been acquired with FLAMES at the Very Large Telescope of
the European Southern Observatory and DEIMOS at the Keck II Telescope.
This is by far the largest spectroscopic sample of stars ever observed
in this stellar system. From this data set, a subsample of targets
with spectra unaffected by TiO bands was extracted and statistically
decontaminated from field stars. Once combined with 34 additional
stars previously published by our group, a total sample of 135 member
stars covering the entire radial extent of the system has been used to
determine the metallicity distribution function of Terzan 5. The iron
distribution clearly shows three peaks: a super-solar component at
[Fe/H]≃0.25 dex, accounting for ∼29% of the sample, a dominant
sub-solar population at [Fe/H]≃-0.30 dex, corresponding to ∼62% of
the total, and a minor (6%) metal-poor component at [Fe/H]≃-0.8 dex.
Such a broad, multi-modal metallicity distribution demonstrates that
Terzan 5 is not a genuine globular cluster but the remnant of a much
more complex stellar system.
Description:
This study is based on a sample of stars located within the tidal
radius of Terzan 5 (rt∼300''; Lanzoni et al. 2010ApJ...717..653L 2010ApJ...717..653L;
Miocchi et al. 2013ApJ...774..151M 2013ApJ...774..151M) observed with two different
instruments: FLAMES (Pasquini et al. 2002Msngr.110....1P 2002Msngr.110....1P) at the
European Southern Observatory (ESO) VLT and DEIMOS (Faber et al.
2003SPIE.4841.1657F 2003SPIE.4841.1657F) at the Keck II Telescope. The spectroscopic
targets have been selected from the optical photometric catalog of
Terzan 5 described in Lanzoni et al. (2010ApJ...717..653L 2010ApJ...717..653L) along the
brightest portion (I<17) of the red giant branch (RGB). In order to
avoid contamination from other sources, we avoided stars with bright
neighbors (Ineighbor<Istar+1.0) within a distance of 2'' in the
selection process of the spectroscopic targets.
Objects:
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RA (ICRS) DE Designation(s)
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17 48 05.00 -24 46 48.0 Terzan 5 = GCl 76.1
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 65 220 Iron abundance of Terzan 5 stars
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See also:
J/A+A/308/733 : NTT VI photometry in Terzan 5 (Ortolani+ 1996)
J/ApJ/726/L20 : Spectroscopy of Terzan 5 (Origlia+, 2011)
J/ApJ/791/101 : Terzan 5 chemical and kinematical properties (Massari+, 2014)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 I8 --- ID Stellar identifier (NNNNNNN) (1)
10- 20 F11.7 deg RAdeg Right Ascension in decimal degrees (J2000)
22- 32 F11.7 deg DEdeg Declination in decimal degrees (J2000)
34- 38 F5.2 mag Kmag The Kc band magnitude
40- 43 I4 K Teff Effective temperature
45- 47 F3.1 [cm/s2] log(g) Log surface gravity
49- 53 F5.2 [-] [Fe/H] Metallicity
55- 58 F4.2 [-] e_[Fe/H] The 1σ uncertainty in [Fe/H]
60- 65 A6 --- Data Dataset identifier (FLAMES, DEIMOS)
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Note (1): Includes all the 220 stars members of Terzan 5 with iron abundance
measured. All stars with Kc<9.6 or Kc>11.7 have been excluded
from the analysis of the metallicity distribution function
(see Section 5.1).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 17-May-2017