J/ApJ/795/52 Red giant star sample from SDSS (Chen+, 2014)
Red giant stars from Sloan Digital Sky Survey.
I. The general field.
Chen Y.Q., Zhao G., Carrell K., Zhao J.K., Tan K.F., Nissen P.E., Wei P.
<Astrophys. J., 795, 52 (2014)>
=2014ApJ...795...52C 2014ApJ...795...52C (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, halo ; Stars, giant ; Stars, distances ;
Abundances, [Fe/H] ; Radial velocities ; Rotational velocities
Keywords: Galaxy: evolution - Galaxy: halo - Galaxy: structure -
stars: abundances - stars: kinematics and dynamics - surveys
Abstract:
We have obtained a sample of ∼22000 red giant branch (RGB) stars
based on stellar parameters, provided by the ninth data release of the
Sloan Digital Sky Survey (Cat. V/139), and the CH(G)/MgH indices,
measured from the included spectra. The Galactic rest-frame velocity
of Vgsr versus longitude for the sample shows the existence of
several groups of stars from globular clusters and known streams.
Excluding these substructures, a sample of ∼16000 RGB stars from the
general field is used to investigate the properties of the thick disk,
the inner halo, and the outer halo of our Galaxy. The metallicity and
rotational velocity distributions are investigated for stars at
0 kpc<|Z|<10 kpc. It is found that the canonical thick disk dominates
at 0 kpc<|Z|<2 kpc and its contribution becomes negligible at
|Z|>3 kpc. The MWTD is present and overlaps with the inner halo at
1 kpc<|Z|<3 kpc. The inner halo starts at 2 kpc<|Z|<3 kpc and
becomes the dominated population for 4 kpc<|Z|<10 kpc. For halo stars
with |Z|>5 kpc, bimodal metallicity distributions are found for
20 kpc<|Z|<25 kpc and 35 kpc<RR<45 kpc, which suggests a dual halo,
the inner and the outer halo, as reported in Carollo et al.
(2007Natur.450.1020C 2007Natur.450.1020C) at low|Z| values. The peak of metallicity for
the inner halo is at [Fe/H]~-1.6 and appears to be at [Fe/H]~-2.3 for
the outer halo. The transition point from the inner to the outer halo
is located at|Z|∼20 kpc and RR∼35 kpc.
Description:
Based on the SDSS DR9 database, we selected stars with (g-r)0
color in the range of 0.1 to 1.0 mag, and log g less than 3.5 dex
for each metallicity bin ranging from [Fe/H]←3.0 to [Fe/H]=0.0
with a step of 0.2 dex, and obtained their spectra. In the selection
and subsequent analysis, stellar parameters (temperature, gravity, and
[Fe/H]) are based on the most recent update of the SEGUE Stellar
Parameter Pipeline (SSPP; Lee et al. 2008AJ....136.2022L 2008AJ....136.2022L, 2008,
J/AJ/136/2050, 2011, J/AJ/141/90; Allende Prieto et al.
2008AJ....136.2070A 2008AJ....136.2070A; Smolinski et al. 2011, J/AJ/141/89). As described
in Ahn et al. (2012ApJS..203...21A 2012ApJS..203...21A), the updated SSPP adopts a
much-improved color-temperature relation from the InfraRed Flux Method
Casagrande et al. (2010, J/A+A/512/A54), and the estimates of surface
gravity and metallicity have been thoroughly recalibrated based on
results from high-resolution observations. An estimate of the internal
uncertainties of the SSPP is ∼50 K for Teff, ∼0.12 dex for log g,
and ∼0.10 dex for [Fe/H]. In order to avoid early-type stars, we limit
the stars to have SSPP temperatures from 3000 K to 10000 K and a
signal-to-noise ratio larger than 10.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 76 15723 The star sample with derived parameters
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See also:
V/139 : The SDSS Photometric Catalog, Release 9
(Adelman-McCarthy+, 2012)
J/AJ/136/2050 : SEGUE stellar parameter pipeline. II. (Lee+, 2008)
J/A+A/512/A54 : Teff and Fbol from Infrared Flux Method (Casagrande+, 2010)
J/A+A/534/A136 : Halo red giants from the SEGUE survey (Martell+, 2011)
J/AJ/141/89 : SEGUE stellar parameter pipeline. IV. (Smolinski+, 2011)
J/AJ/141/90 : SEGUE stellar parameter pipeline. V. (Lee+, 2011)
J/ApJ/769/87 : Kinematics of halo red giants (Carollo+, 2013)
J/ApJ/794/60 : SDSS RGB stars distances (Tan+, 2014)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Plate SDSS plate number
6- 10 I5 d MJD Modified Julian Date of the observation
12- 14 I3 --- Fiber SDSS Fiber number
16- 21 F6.2 kpc Dist Distance
23- 27 F5.2 kpc e_Dist Error in Dist
29- 35 F7.2 kpc Xpos Galactic X coordinate
37- 42 F6.2 kpc Ypos Galactic Y coordinate
44- 49 F6.2 kpc Zpos Galactic Z coordinate
51- 55 F5.2 [-] [Fe/H] Metallicity
57- 62 F6.1 km/s RVel Radial velocity
64- 69 F6.1 km/s Vgsr Galactic rest-frame velocity
71- 76 F6.1 km/s Vphi ? Rotational velocity
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History:
From electronic version of the journal
References:
Tan et al., Paper II, 2014ApJ...794...60T 2014ApJ...794...60T
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 18-May-2017