J/ApJ/762/26 Most metal-poor stars. II. 190 Galactic halo stars (Yong+, 2013)
The most metal-poor stars.
II. Chemical abundances of 190 metal-poor stars including 10 new stars
with [Fe/H] ≤ -3.5.
Yong D., Norris J.E., Bessell M.S., Christlieb N., Asplund M., Beers T.C.,
Barklem P.S., Frebel A., Ryan S.G.
<Astrophys. J., 762, 26 (2013)>
=2013ApJ...762...26Y 2013ApJ...762...26Y
ADC_Keywords: Abundances ; Stars, halo ; Stars, metal-deficient ;
Effective temperatures
Keywords: early universe; Galaxy: formation; Galaxy: halo;
nuclear reactions, nucleosynthesis, abundances; stars: abundances
Abstract:
We present a homogeneous chemical abundance analysis of 16 elements in
190 metal-poor Galactic halo stars (38 program and 152 literature
objects). The sample includes 171 stars with [Fe/H]≤-2.5, of which 86
are extremely metal poor, [Fe/H]≤-3.0. Our program stars include 10
new objects with [Fe/H]≤-3.5. We identify a sample of "normal"
metal-poor stars and measure the trends between [X/Fe] and [Fe/H], as
well as the dispersion about the mean trend for this sample. Using
this mean trend, we identify objects that are chemically peculiar
relative to "normal" stars at the same metallicity. These chemically
unusual stars include CEMP-no objects, one star with high [Si/Fe],
another with high [Ba/Sr], and one with unusually low [X/Fe] for all
elements heavier than Na. The Sr and Ba abundances indicate that there
may be two nucleosynthetic processes at lowest metallicity that are
distinct from the main r-process. Finally, for many elements, we find
a significant trend between [X/Fe] versus Teff, which likely
reflects non-LTE and/or three-dimensional effects. Such trends
demonstrate that care must be exercised when using abundance
measurements in metal-poor stars to constrain chemical evolution
and/or nucleosynthesis predictions.
Description:
In Norris et al. (2013; Paper I, Cat. J/ApJ/762/25) we describe
high-resolution spectroscopic observations of 38 program stars
(obtained in 2007-2008 using the Keck, Magellan, and VLT telescopes),
including the discovery and sample selection, equivalent-width
measurements, radial velocities, and line list. Our sample comprises
34 stars original to the present work, together with four for which
published abundances already exist, or which are the subject of
analyses currently underway.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 66 47 Model atmosphere parameters and [Fe/H] for the 38
program stars
table2.dat 45 47 C and N abundances for the 38 program stars
table3.dat 53 752 Chemical abundances (Na-Ba) for the program stars
table4.dat 63 752 Abundance errors from uncertainties in atmospheric
parameters for the 38 program stars
table6.dat 76 152 Model atmosphere parameters and [Fe/H] for the
literature Sample
table7.dat 122 152 Chemical abundances (C-Ba) for the literature sample
table9.dat 183 199 Model atmosphere parameters and chemical abundances,
[X/Fe], for the complete sample (literature+program)
--------------------------------------------------------------------------------
See also:
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
J/ApJ/762/27 : Pap. III: metallicity distribution function (Yong+, 2013)
J/ApJ/762/25 : Pap. I: Discovery, data & atmospheric param. (Norris+, 2013)
J/A+A/541/A143 : NLTE Corrections of the Ca lines (Spite+, 2012)
J/ApJS/199/38 : Presupernova evolution (Limongi+, 2012)
J/ApJ/742/54 : CASH project II. Extremely metal-poor stars (Hollek+, 2011)
J/A+A/534/A136 : Halo red giants from the SEGUE survey (Martell+, 2011)
J/MNRAS/412/843 : SAGA extremely metal-poor stars (Suda+, 2011)
J/MNRAS/403/1413 : Updated stellar yields from AGB models (Karakas, 2010)
J/ApJ/724/975 : Metal-poor stars heavy element abundances (Roederer+, 2010)
J/ApJ/724/341 : Nucleosynthesis of massive metal-free stars (Heger+, 2010)
J/ApJ/711/350 : Metal-poor giant Boo-1137 abundances (Norris+, 2010)
J/A+A/513/A35 : Abundances of Galactic red giants (Alves-Brito+, 2010)
J/A+A/512/A54 : Teff and Fbol from Infrared Flux Method (Casagrande+, 2010)
J/A+A/511/L10 : Abundances and space velocities of 94 stars (Nissen+, 2010)
J/A+A/509/A93 : Carbon-enhanced metal-poor stars (Masseron+, 2010)
J/A+A/503/545 : EWs of Li, Na, Fe, Ca in NGC 6397 (Lind+, 2009)
J/A+A/503/541 : Late-type stars neutral Li non-LTE estimations (Lind+, 2009)
J/A+A/501/519 : Extremely metal-poor stars abundances (Bonifacio+, 2009)
J/AJ/137/272 : Space velocities orbits in the MW halo (Roederer+ 2009)
J/ApJ/681/1524 : Detailed abundances for 28 metal-poor stars (Lai+, 2008)
J/ApJ/658/1203 : Nitrogen-enhanced metal-poor stars (Johnson+, 2007)
J/ApJ/658/367 : Abundances of carbon stars in Galactic halo (Komiya+, 2007)
J/ApJ/655/492 : Equivalent widths of 26 metal-poor stars (Aoki+, 2007)
J/AJ/132/137 : Extremely metal-poor carbon stars abundances (Cohen+, 2006)
J/A+A/439/129 : HERES II. Spectroscopic analysis (Barklem+, 2005)
J/A+A/420/183 : Spectro. survey in solar neighborhood (Allende Prieto+ 2004)
J/A+A/416/1117 : Abundances in the early Galaxy (Cayrel+, 2004)
J/MNRAS/340/304 : [X/Fe] of Galactic disc F and G dwarfs (Reddy+, 2003)
J/A+A/326/751 : Chemical composition of halo and disk stars (Nissen+, 1997)
Byte-by-byte Description of file: table[16].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- Name Star name
16 A1 --- f_Name [cd] assumed gravity (G1)
18- 19 I2 h RAh 2MASS hour of right ascension (J2000)
21- 22 I2 min RAm 2MASS minute of right ascension (J2000)
24- 27 F4.1 s RAs 2MASS second of right ascension (J2000)
29 A1 --- DE- 2MASS sign of declination (J2000)
30- 31 I2 deg DEd 2MASS degree of declination (J2000)
33- 34 I2 arcmin DEm 2MASS arcminute of declination (J2000)
36- 39 F4.1 arcsec DEs 2MASS arcsecond of declination (J2000)
41- 44 I4 K Teff [4430/6635]? Effective temperature
46- 49 F4.2 [cm/s2] logg [0.7/4.7]? log of surface gravity
51- 53 F3.1 km/s xi [0.3/3.4]? Turbulent velocity (ξt)
55- 58 F4.1 [-] [M/H] [-5.5/-1]? Model metallicity [M/H]
60- 64 F5.2 [-] [Fe/H] [-5.8/-1]? Derived iron abundance [Fe/H]
66 I1 --- C-rich [0/1]? Carbon-rich source code (0=C-normal) (G2)
68- 76 A9 --- Ref Reference source codes (only for table 6) (G3)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- Name Star name
16 A1 --- f_Name [cd] assumed gravity (G1)
18 A1 --- l_A(C) Limit flag on A(C)
20- 23 F4.2 --- A(C) [4.5/8.3] C abundance
25 A1 --- l_[C/Fe] Limit flag on [C/Fe]
27- 31 F5.2 --- [C/Fe] [-0.27/2.82] [C/Fe] abundance ratio
33 A1 --- l_A(N) Limit flag on A(N)
35- 38 F4.2 --- A(N) [4.7/7.5]? N abundance
40 A1 --- l_[N/Fe] Limit flag on [N/Fe]
42- 45 F4.2 --- [N/Fe] [0.42/2.91]? [N/Fe] abundance ratio
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- Ion Ion identification
7- 20 A14 --- Name Star identifier
22 A1 --- f_Name [cd] assumed gravity (G1)
24 A1 --- l_A(X) Limit on A(X)
25- 30 F6.2 [-] A(X) [-3.5/6.1]? Log abundance in Ion
32- 34 I3 --- o_A(X) [1/102]? Number of lines used to determine A(X)
36- 39 F4.2 [-] s_A(X) [0/0.6]? Standard error of the mean in A(X)
41- 44 F4.2 [-] e_A(X) [0.08/0.6]? Total error in A(X) (1)
46 A1 --- l_X/Fe Limit flag on X/Fe
47- 51 F5.2 [-] X/Fe [-4.1/2.2]? Log of the Ion/Fe abundance
53 A1 --- f_X/Fe [efg] How X/Fe was determined (2)
--------------------------------------------------------------------------------
Note (1): Total error is the quadratic sum of the updated random error and the
systematic error (see Section 2.3 for details).
Note (2): Flag as follows:
e = Abundances, or limits, were determined from spectrum synthesis of
the 4102.94Å Si line.
f = Abundances limits were determined from the 4077.71Å Sr line.
g = Abundances limits were determined from the 4554.03Å Ba line.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- Name Star name
16 A1 --- f_Name [cd] assumed gravity (G1)
18- 34 A17 --- Param Parameter identifier
36- 40 F5.2 [-] DT [-0.1/0.2]? Abundance error from 100K change
42- 46 F5.2 [-] Dlogg [-0.2/0.2]? Abundance error from 0.3dex log(g)
change
48- 52 F5.2 [-] Dxi [-0.2/0.03]? Abundance error from 0.3km/s ξt
change
54- 58 F5.2 [-] DM/H [-0.2/0.2]? Abundance error from 0.3dex M/H change
60- 63 F4.2 [-] DX/Fe [0.01/0.3]? Abundance error from 1dex [X/Fe] change
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- Name Star identifier
18 A1 --- l_C/Fe Limit flag on C/Fe
19- 24 F6.2 [-] C/Fe [-0.8/4.3]? Log of the C/Fe abundance (1)
26 A1 --- l_N/Fe Limit flag on N/Fe
27- 32 F6.2 [-] N/Fe [-0.8/4.6]? Log of the N/Fe abundance (1)
34- 38 F5.2 [-] Na/Fe [-0.4/2.5]? Log of the Na/Fe abundance
40- 44 F5.2 [-] Mg/Fe ? Log of the Mg/Fe abundance
46- 50 F5.2 [-] Al/Fe [-1.2/1.3]? Log of the Al/Fe abundance
52- 56 F5.2 [-] Si/Fe [-0.9/1]? Log of the Si/Fe abundance
58- 62 F5.2 [-] Ca/Fe ? Log of the Ca/Fe abundance
64- 68 F5.2 [-] Sc/Fe ? Log of the Sc/Fe abundance
70- 74 F5.2 [-] TiI/Fe ? Log of the Ti I/Fe abundance
76- 80 F5.2 [-] TiII/Fe ? Log of the Ti II/Fe abundance
82- 86 F5.2 [-] Cr/Fe ? Log of the Cr/Fe abundance
88- 92 F5.2 [-] Mn/Fe [-1/0.2]? Log of the Mn/Fe abundance
94- 98 F5.2 [-] FeII/H [-4.2/-1.3]? Log of the FeII/H abundance
100-104 F5.2 [-] Co/Fe ? Log of the Co/Fe abundance
106-110 F5.2 [-] Ni/Fe ? Log of the Ni/Fe abundance
112-116 F5.2 [-] Sr/Fe [-2.1/1.9]? Log of the Sr/Fe abundance
118-122 F5.2 [-] Ba/Fe [-2.1/2.7]? Log of the Ba/Fe abundance
--------------------------------------------------------------------------------
Note (1): For [C/Fe] and [N/Fe], the values are taken from the literature
reference.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table9.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- Name Star identifier
18 A1 --- f_Name [cd] assumed gravity (G1)
20- 21 I2 h RAh 2MASS Hour of Right Ascension (J2000)
23- 24 I2 min RAm 2MASS Minute of Right Ascension (J2000)
26- 29 F4.1 s RAs 2MASS Second of Right Ascension (J2000)
31 A1 --- DE- 2MASS Sign of the Declination (J2000)
32- 33 I2 deg DEd 2MASS Degree of Declination (J2000)
35- 36 I2 arcmin DEm 2MASS Arcminute of Declination (J2000)
38- 41 F4.1 arcsec DEs 2MASS Arcsecond of Declination (J2000)
43- 46 I4 K Teff [4430/6635] Effective temperature
48- 51 F4.2 [cm/s2] log(g) [0.7/4.7]? Log of the surface gravity
53- 57 F5.2 [-] Fe/H [-5.8/-1]? Log of the Fe/H abundance
59 I1 --- C-rich [0/1]? Carbon rich source (0=C-normal) (G2)
61 A1 --- l_C Limit flag on C
62- 67 F6.2 [-] C [-0.8/4.3]? Log of the C abundance (1)
69 A1 --- l_N Limit flag on N
70- 75 F6.2 [-] N [-0.8/4.6]? Log of the N abundance (1)
77- 81 F5.2 [-] Na [-0.5/2.5]? Log of the Na abundance
83- 87 F5.2 [-] Mg ? Log of the Mg abundance
89- 93 F5.2 [-] Al [-1.2/1.3]? Log of the Al abundance
95 A1 --- l_Si Limit flag on Si
96-100 F5.2 [-] Si [-0.9/2]? Log of the Si abundance
102-106 F5.2 [-] Ca ? Log of the Ca abundance
108-112 F5.2 [-] Sc ? Log of the Sc abundance
114-118 F5.2 [-] TiI ? Log of the Ti I abundance
120-124 F5.2 [-] TiII ? Log of the Ti II abundance
126-130 F5.2 [-] Cr ? Log of the Cr abundance
132-136 F5.2 [-] Mn [-1/0.2]? Log of the Mn abundance
138-142 F5.2 [-] FeII [-4.2/-1.3]? Log of the Fe II abundance
144-148 F5.2 [-] Co ? Log of the Co abundance
150-154 F5.2 [-] Ni ? Log of the Ni abundance
156 A1 --- l_Sr Limit flag on Sr
157-161 F5.2 [-] Sr [-2.3/1.9]? Log of the Sr abundance
163 A1 --- f_Sr [f] Abundance from literature (2)
165 A1 --- l_Ba Limit flag on Ba
166-170 F5.2 [-] Ba [-2.1/2.7]? Log of the Ba abundance
172 A1 --- f_Ba [f] Abundance from literature (2)
174-183 A10 --- Ref Reference(s) code (G3)
--------------------------------------------------------------------------------
Note (1): For literature stars, [C/Fe] and [N/Fe] values are taken from the
literature reference.
Note (2):
f = This abundance, or limit, was taken from the literature source.
--------------------------------------------------------------------------------
Global notes:
Note (G1): Flag Jas follows:
c = For this set of results, a dwarf gravity is assumed
(see Section 2.1 for details).
d = For this set of results, a subgiant gravity is assumed
(see Section 2.1 for details).
Note (G2): Flag is:
1 = carbon-enhanced metal-poor (CEMP) object, adopting the Aoki et al.
(2007, Cat. J/ApJ/655/492) definition
0 = C-normal (see Section 7.1 for details).
Note (G3): Reference as follows:
1 = Aoki et al. (2002PASJ...54..933A 2002PASJ...54..933A);
2 = Aoki et al. (2006ApJ...639..897A 2006ApJ...639..897A);
3 = Aoki et al. (2007, Cat. J/ApJ/655/492);
4 = Aoki et al. (2008ApJ...678.1351A 2008ApJ...678.1351A);
5 = Bonifacio et al. (2007A&A...462..851B 2007A&A...462..851B, 2009, Cat. J/A+A/501/519);
6 = Carretta et al. (2002AJ....124..481C 2002AJ....124..481C); Cohen et al. (2002AJ....124..470C 2002AJ....124..470C);
7 = Cayrel et al. (2004, Cat. J/A+A/416/1117);
8 = Christlieb et al. (2004ApJ...603..708C 2004ApJ...603..708C);
9 = Cohen et al. (2004ApJ...612.1107C 2004ApJ...612.1107C);
10 = Cohen et al. (2006, Cat. J/AJ/132/137);
11 = Cohen et al. (2008ApJ...672..320C 2008ApJ...672..320C);
12 = Frebel et al. (2007ApJ...658..534F 2007ApJ...658..534F);
13 = Honda et al. (2004ApJS..152..113H 2004ApJS..152..113H);
14 = Lai et al. (2008, Cat. J/ApJ/681/1524);
15 = Norris et al. (2001ApJ...561.1034N 2001ApJ...561.1034N);
16 = Norris et al. (2007ApJ...670..774N 2007ApJ...670..774N);
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History:
From electronic version of the journal
* 27-Oct-2014: Insert into VizieR
* 20-Feb-2014: Coordinates corrected for HE 0355-3728 in tables 1 and 9;
we acknowledge the author David Yong (Australian National University).
References:
Norris et al. Paper I. 2013ApJ...762...25N 2013ApJ...762...25N Cat. J/ApJ/762/25
Yong et al. Paper III. 2013ApJ...762...27Y 2013ApJ...762...27Y Cat. J/ApJ/762/27
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 28-Aug-2014