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J/ApJ/788/180   Very metal-poor stars in the Milky Way's halo   (Carollo+, 2014)

Carbon-enhanced metal-poor stars: CEMP-s and CEMP-no subclasses in the halo system of the Milky Way. Carollo D., Freeman K., Beers T.C., Placco V.M., Tumlinson J., Martell S.L. <Astrophys. J., 788, 180 (2014)> =2014ApJ...788..180C (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, metal-deficient ; Effective temperatures ; Abundances, [Fe/H] ; Radial velocities ; Proper motions Keywords: Galaxy: evolution - Galaxy: formation - Galaxy: halo - Galaxy: structure - stars: abundances - surveys Abstract: We explore the kinematics and orbital properties of a sample of 323 very metal-poor stars in the halo system of the Milky Way, selected from the high-resolution spectroscopic follow-up studies of Aoki et al. (2013, J/AJ/145/13) and Yong et al (2013, J/ApJ/762/26). The combined sample contains a significant fraction of carbon-enhanced metal-poor (CEMP) stars (22% or 29%, depending on whether a strict or relaxed criterion is applied for this definition). Barium abundances (or upper limits) are available for the great majority of the CEMP stars, allowing for their separation into the CEMP-s and CEMP-no subclasses. A new method to assign membership to the inner- and outer-halo populations of the Milky Way is developed, making use of the integrals of motion, and applied to determine the relative fractions of CEMP stars in these two subclasses for each halo component. Although limited by small-number statistics, the data suggest that the inner halo of the Milky Way exhibits a somewhat higher relative number of CEMP-s stars than CEMP-no stars (57% versus 43%), while the outer halo possesses a clearly higher fraction of CEMP-no stars than CEMP-s stars (70% versus 30%). Although larger samples of CEMP stars with known Ba abundances are required, this result suggests that the dominant progenitors of CEMP stars in the two halo components were different; massive stars for the outer halo, and intermediate-mass stars in the case of the inner halo. Description: The Aoki et al. (2013, J/AJ/145/13) sample comprises 137 stars observed at high spectral resolution (R∼30000), in the course of four observing runs between 2008 March and October, using the High Dispersion Spectrograph (Noguchi et al. 2002PASJ...54..855N) at the Subaru Telescope. We also include 190 stars from the Yong et al. (2013, J/ApJ/762/26) sample - the 38 stars from their "program sample," and 152 stars in their literature compilation. High-resolution spectra (22000<R<85000) of the program sample stars were taken between 2007 June and 2008 September, using the MIKE spectrograph (Bernstein et al. 2003SPIE.4841.1694B) on the Magellan Clay Telescope at Las Campanas Observatory, the HIRES spectrograph (Vogt et al. 1994SPIE.2198..362V) at Keck Observatory, or the UVES spectrograph (Dekker et al. 2000SPIE.4008..534D) on VLT UT2 (Kueyen) at the European Southern Observatory. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 123 137 Parameters for the Sample of Aoki et al. (2013, J/AJ/145/13) table2.dat 123 190 Parameters for the Sample of Yong et al. (2013, J/ApJ/762/26)
See also: J/A+A/290/885 : Abundances of very metal-poor stars (Primas+, 1994) J/AJ/119/2866 : Proper motions of metal-poor stars (Beers+, 2000) J/AJ/145/13 : Metal-poor stars from SDSS/SEGUE. I. Abundances (Aoki+, 2013) J/ApJ/762/26 : Most metal-poor stars. II. 190 Galactic halo stars (Yong+, 2013) J/ApJ/778/56 : Hamburg/ESO Survey extremely metal-poor stars (Cohen+, 2013) J/AJ/147/136 : Stars of very low metal abundance. VI. Abundances (Roederer+, 2014) Byte-by-byte Description of file: table1.dat table2.dat
Bytes Format Units Label Explanations
1- 14 A14 --- Name Source identifier (Plate-MJD-Fiber in table1.dat) 16- 18 A3 --- f_Name Flag on Name (1) 20- 23 I4 K Teff Effective temperature 25- 27 F3.1 [cm/s2] log(g) Log surface gravity 29- 33 F5.2 [-] [Fe/H] Metallicity 35- 40 F6.1 km/s RV Adopted radial velocity 42- 44 F3.1 km/s e_RV Uncertainty in RV 46- 52 F7.3 deg RAdeg Right Ascension in decimal degrees (J2000) 54- 60 F7.3 deg DEdeg Declination in decimal degrees (J2000) 62- 69 F8.2 mas/yr pmRA ? Proper motion in Right Ascension (pmRA*cosDE) 71- 77 F7.2 mas/yr pmDE ? Proper motion in Declination 79- 82 F4.2 mas/yr e_pmRA ? Uncertainty in pmRA 84- 87 F4.2 mas/yr e_pmDE ? Uncertainty in pmDE 89- 93 F5.2 kpc Dist ? Distance 95 A1 --- l_[C/Fe] [<] Limit flag on [C/Fe] 97-101 F5.2 [-] [C/Fe] ? The [C/Fe] abundance ratio 103 A1 --- l_[Ba/Fe] [<] Limit flag on [Ba/Fe] 105-109 F5.2 [-] [Ba/Fe] ? The [Ba/Fe] abundance ratio 111 I1 --- C [0/3]? Carbon code (2) 113 I1 --- Ba [0/4]? Barium code (3) 115-116 A2 --- Class [s no] Adopted CEMP classification 118-121 A4 --- Sample Sample (4) 123 A1 --- Member [IOTU] Member flag (5)
Note (1): Flag as follows: a = This star does not have a well-measured distance available; b = This star does not have a well-measured proper motion available; c = This star is unbound from the Galaxy, according to its derived orbital parameters; d = Unknown [BaFe], but classified as CEMP-no by Aoki et al. 2013, J/AJ/145/13; e = Likely CEMP (+0.5≤[C/Fe]<+0.7); CEMP-s (Ba≥+0.8); CEMP-no (0.0≤[Ba/Fe]≤+0.3, or based on pattern of light-element abundances; f = This star is also in the Yong et al. (2013, J/ApJ/762/26) sample - 2848-54453-252=CS∼29527-015; 2044-53327-515=53327-2044-515; 2667-54142-094=54142-2667-094; 2036-53446-324=53436-1996-093; g = CS 22957-027; h = Elemental abundances taken from Cohen et al. (2013, J/ApJ/778/56); i = Elemental abundances taken from Roederer et al. (2014, J/AJ/147/136); j = This star is also in the Aoki et al. (2013, J/AJ/145/13) sample - CS 29527-015=2848-54453-252; 53327-2044-515=2044-53327-515; 54142-2667-094=2667-54142-094; 53436-1996-093=2036-53446-324. Note (2): Code as follows: 0 = No carbon is detected (carbon-unknown); 1 = Carbon measurement indicates upper limit on [C/Fe]>+0.7 (carbon-indeterminate); 2 = Carbon measurement indicates [C/Fe]<+0.7 or upper limit on [C/Fe] indicates [C/Fe]<+0.7 (carbon-normal); 3 = Carbon measurement indicates [C/Fe]≥+0.7 or lower limit on [C/Fe] indicates [C/Fe]>+0.7 (carbon-enhanced). Note (3): Code as follows: 0 = No barium is detected (barium-unknown); 1 = Barium measurement indicates upper limit on [Ba/Fe]>0.0 (barium-indeterminate); 2 = Barium measurement indicates 0.0<[Ba/Fe]<+1.0 (barium-normal); 3 = Barium measurement indicates [Ba/Fe]≥+1.0 (barium-enhanced); 4 = Barium measurement indicates [Ba/Fe]≤0.0 or upper limit on [Ba/Fe]≤0 (barium-deficient). Note (4): The assignment into the sub-sample used for the kinematic analysis in the form of a 4 digit code, with each digit set to 1 if the star is a member of the sub-sample, 0 if not, in the order - Strict Sample (SS), Extended Sample (ES), CEMP star without sub-class assignment in Strict Sample (CSS), and CEMP star without sub-class assignment in Extended Sample (CES). Note (5): The halo component into which stars with kinematic information have been assigned based on the criteria described in the text. Flag as follows: I = Indicates inner halo; O = Indicates outer halo; T = Indicates the transition zone; U = Indicates that the star was unclassified (star is on an unbound orbit, or is missing the information required for making this assignment).
History: From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 19-Jul-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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