J/ApJ/791/101 Terzan 5 chemical and kinematical properties (Massari+, 2014)
Chemical and kinematical properties of Galactic bulge stars surrounding
the stellar system Terzan 5.
Massari D., Mucciarelli A., Ferraro F.R., Origlia L., Rich R.M.,
Lanzoni B., Dalessandro E., Ibata R., Lovisi L., Bellazzini M., Reitzel D.
<Astrophys. J., 791, 101 (2014)>
=2014ApJ...791..101M 2014ApJ...791..101M (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Clusters, globular ; Abundances, [Fe/H] ;
Effective temperatures
Keywords: Galaxy: bulge - stars: abundances - techniques: radial velocities -
techniques: spectroscopic
Abstract:
As part of a study aimed at determining the kinematical and chemical
properties of Terzan 5, we present the first characterization of the
bulge stars surrounding this puzzling stellar system. We observed 615
targets located well beyond the tidal radius of Terzan 5 and found
that their radial velocity distribution is well described by a
Gaussian function peaked at <vrad> = +21.0±4.6 km/s with
dispersion σv= 113.0±2.7 km/s. This is one of the few
high-precision spectroscopic surveys of radial velocities for a large
sample of bulge stars in such a low and positive latitude environment
(b = +1.7°). We found no evidence of the peak at
<vrad> ∼ +200 km/s found in Nidever et al. (2012ApJ...755L..25N 2012ApJ...755L..25N).
Strong contamination of many observed spectra by TiO bands prevented
us from deriving the iron abundance for the entire spectroscopic
sample, introducing a selection bias. The metallicity distribution was
finally derived for a subsample of 112 stars in a magnitude range
where the effect of the selection bias is negligible. The distribution
is quite broad and roughly peaked at solar metallicity
([Fe/H] ≃ +0.05 dex) with a similar number of stars in the
super-solar and in the sub-solar ranges. The population number ratios
in different metallicity ranges agree well with those observed in
other low-latitude bulge fields, suggesting (1) the possible presence
of a plateau for|b| < 4° in the ratio between stars in the
super-solar (0 < [Fe/H] <0.5 dex) and sub-solar (-0.5 < [Fe/H] <0 dex)
metallicity ranges; (2) a severe drop in the metal-poor component
([Fe/H] ←0.5) as a function of Galactic latitude.
Description:
This study is based on a sample of 1608 stars within a radius of 800''
from the center of Terzan 5 (αJ2000=17h:48m:4.85s,
δJ2000=-24°:46':44.6''; see Ferraro et al. 2009Natur.462..483F 2009Natur.462..483F;
Lanzoni et al. 2010ApJ...717..653L 2010ApJ...717..653L). While the overall survey will be
described in a forthcoming paper (F. Ferraro et al., in preparation),
in this work we focus on a subsample of stars representative of the
field population surrounding Terzan 5. Given the value of the tidal
radius of the system (rt ∼ 300''; Lanzoni et al. 2010ApJ...717..653L 2010ApJ...717..653L;
Miocchi et al. 2013ApJ...774..151M 2013ApJ...774..151M), we conservatively selected as
genuine field population members all the targets more distant than
400'' from the center of Terzan 5. This subsample is composed of 615
stars belonging to two different data sets obtained with FLAMES
(Pasquini et al. 2002Msngr.110....1P 2002Msngr.110....1P) at the ESO VLT and with DEIMOS
(Faber et al. 2003SPIE.4841.1657F 2003SPIE.4841.1657F) at the Keck II Telescope. Each
target has been selected from the ESO-Wide Field Imager (WFI) optical
catalog described in Lanzoni et al. (2010ApJ...717..653L 2010ApJ...717..653L), along the
brightest portion of the red giant branch (RGB), with magnitudes
brighter than I<18.5.
Objects:
----------------------------------------------------------
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 59 284 Identification number, coordinates,
atmospheric parameters, iron abundances and
their uncertainties for the Terzan 5 field
stars in our sample
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See also:
J/ApJ/699/66 : Abundances in two Galactic bulge stars (Cohen+, 2009)
J/A+A/534/A91 : Galactic Bulge Valinhos Observatory Catalog (Teixeira+, 2011)
J/A+A/580/A121 : CaT/[Fe/H] calibration for Galactic bulge stars
(Vasquez+, 2015)
J/A+A/587/A124 : Metal-poor stars towards the Galactic bulge (Koch+, 2016)
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 Star Identifier (NNNNNNN)
10- 20 F11.7 deg RAdeg Right Ascension in decimal degrees (J2000)
22- 32 F11.7 deg DEdeg Declination in decimal degrees (J2000)
34- 37 I4 K Teff Effective temperature
39- 41 F3.1 [cm/s2] log(g) Log surface gravity
43- 47 F5.2 [-] [Fe/H] Metallicity
49- 52 F4.2 [-] e_[Fe/H] The 1σ uncertainty in [Fe/H]
54- 59 A6 --- Data Data set origin (FLAMES, DEIMOS)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 29-Mar-2017