J/ApJ/833/20 Carbon-enhanced metal-poor (CEMP) star abundances (Yoon+, 2016)
Observational constraints on first-star nucleosynthesis.
I. Evidence for multiple progenitors of CEMP-no stars.
Yoon J., Beers T.C., Placco V.M., Rasmussen K.C., Carollo D., He S.,
Hansen T.T., Roederer I.U., Zeanah J.
<Astrophys. J., 833, 20-20 (2016)>
=2016ApJ...833...20Y 2016ApJ...833...20Y (SIMBAD/NED BibCode)
ADC_Keywords: Abundances ; Stars, metal-deficient ; Stars, carbon
Keywords: stars: abundances; stars: AGB and post-AGB; stars: chemically peculiar
stars: evolution; stars: massive; stars: Population II
Abstract:
We investigate anew the distribution of absolute carbon abundance,
A(C)=logε(C), for carbon-enhanced metal-poor (CEMP) stars in
the halo of the Milky Way, based on high-resolution spectroscopic data
for a total sample of 305 CEMP stars. The sample includes 147 CEMP-s
(and CEMP-r/s) stars, 127 CEMP-no stars, and 31 CEMP stars that are
unclassified, based on the currently employed [Ba/Fe] criterion. We
confirm previous claims that the distribution of A(C) for CEMP stars
is (at least) bimodal, with newly determined peaks centered on
A(C)=7.96 (the high-C region) and A(C)=6.28 (the low-C region). A very
high fraction of CEMP-s (and CEMP-r/s) stars belongs to the high-C
region, while the great majority of CEMP-no stars resides in the low-C
region. However, there exists complexity in the morphology of the
A(C)-[Fe/H] space for the CEMP-no stars, a first indication that more
than one class of first-generation stellar progenitors may be required
to account for their observed abundances. The two groups of CEMP-no
stars we identify exhibit clearly different locations in the
A(Na)-A(C) and A(Mg)-A(C) spaces, also suggesting multiple
progenitors. The clear distinction in A(C) between the CEMP-s (and
CEMP-r/s) stars and the CEMP-no stars appears to be as successful, and
likely more astrophysically fundamental, for the separation of these
sub-classes as the previously recommended criterion based on [Ba/Fe]
(and [Ba/Eu]) abundance ratios. This result opens the window for its
application to present and future large-scale low- and
medium-resolution spectroscopic surveys.
Description:
We have endeavored to compile a list that is as complete as possible
of carbon-enhanced metal-poor (CEMP); CEMP-s (and CEMP-r/s) and
CEMP-no stars having [Fe/H]←1.0 and [C/Fe]≥+0.7 with available
high-resolution spectroscopic abundance information. We have only
considered stars with claimed detections or lower limits for carbon,
along with several critical elemental-abundance ratios, such as
[Ba/Fe] and [Eu/Fe]. The great majority of our sample comes from the
literature compilation of Placco+ (2014, J/ApJ/797/21).
See section 2 for further details.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 182 305 Literature data and classifications for
Carbon-Enhanced Metal-Poor (CEMP) stars
table2.dat 114 104 Na and Mg abundances for the Group II and
Group III CEMP-no stars
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See also:
J/ApJ/824/L19 : BD+44493 CEMP star equivalent widths (Roederer+, 2016)
J/A+A/586/A158 : Binary properties of CH and CEMP stars (Jorissen+, 2016)
J/ApJ/814/121 : CASH project. III. The CEMP star HE0414-0343 (Hollek+, 2015)
J/ApJ/812/109 : HST+Keck spectroscopy of bright CEMP-s stars (Placco+, 2015)
J/A+A/581/A22 : 67 CEMP-s stars model analysis (Abate+, 2015)
J/ApJ/807/171 : SkyMapper Survey metal-poor star spectrosc. (Jacobson+, 2015)
J/A+A/579/A28 : Abundances of 3 CEMP stars (Bonifacio+, 2015)
J/ApJ/797/21 : Carbon-enhanced metal-poor stars (Placco+, 2014)
J/AJ/147/136 : Stars of very low metal abundance. VI. (Roederer+, 2014)
J/ApJ/781/40 : Metal-poor stars from HES survey. II. (Placco+, 2014)
J/ApJ/778/56 : Hamburg/ESO Survey extremely metal-poor stars (Cohen+, 2013)
J/ApJ/773/33 : The metal-poor subgiant BD+44 493 chemical data (Ito+, 2013)
J/ApJ/769/57 : Equivalent widths of metal-poor stars (Frebel+, 2013)
J/ApJ/762/26 : Most metal-poor stars. II. Galactic halo stars (Yong+, 2013)
J/ApJ/762/25 : The most metal-poor stars in HES and SDSS. I. (Norris+, 2013)
J/AJ/145/13 : Metal-poor stars from SDSS/SEGUE. I. Abundances (Aoki+, 2013)
J/A+A/548/A34 : Abundances od Carbon-enhanced metal-poor stars (Allen+, 2012)
J/MNRAS/418/284 : s-process in low-metallicity stars. II. (Bisterzo+, 2011)
J/ApJ/742/54 : CASH project II. extremely metal-poor stars (Hollek+, 2011)
J/MNRAS/412/843 : SAGA extremely metal-poor stars (Suda+, 2011)
J/ApJ/724/341 : Nucleosynthesis of massive metal-free stars (Heger+, 2010)
J/MNRAS/404/253 : Heavy element abundances in HD 209621 (Goswami+, 2010)
J/A+A/509/A93 : Carbon-enhanced metal-poor stars (Masseron+, 2010)
J/A+A/490/769 : Yields from extremely metal-poor stars (Campbell+, 2008)
J/ApJ/679/1549 : Spectrosc. of metal-poor star CS17435-00532 (Roederer+, 2008)
J/ApJ/655/492 : Equivalent widths of 26 metal-poor stars (Aoki+, 2007)
J/A+A/439/129 : HERES II. Spectroscopic analysis (Barklem+, 2005)
J/ApJ/617/1091 : La and Eu abundances in 85 stars (Simmerer+, 2004)
J/A+A/354/169 : Metal-poor field stars abundances (Gratton+, 2000)
J/AJ/103/1987 : Stars of very low metal abundance (Beers+ 1992)
J/AJ/90/2089 : Stars of very low metal abundance. I (Beers+, 1985)
http://sagadatabase.jp/ : SAGA -Stellar Abundances for Galactic Archeology
Database
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- Group Object group (G1)
14- 30 A17 --- Name Identifier (1)
32 A1 --- f_Name Flag on Name (2)
34- 35 I2 h RAh Hour of Right Ascension (J2000)
37- 38 I2 min RAm Minute of Right Ascension (J2000)
40- 46 F7.4 s RAs Second of Right Ascension (J2000)
48 A1 --- DE- Sign of the Declination (J2000)
49- 50 I2 deg DEd Degree of Declination (J2000)
52- 53 I2 arcmin DEm Arcminute of Declination (J2000)
55- 61 F7.4 arcsec DEs Arcsecond of Declination (J2000)
63- 66 I4 K Teff [3500/7000] Effective temperature
68- 71 F4.2 [cm/s2] log(g) [0.1/5.1] Log surface gravity
73 A1 --- l_[Fe/H] Limit flag on [Fe/H]
75- 79 F5.2 [Sun] [Fe/H] [-8/3.1] Metallicity
81 A1 --- l_[C/Fe] Limit flag on [C/Fe]
82- 86 F5.2 [Sun] [C/Fe] [-0.01/5.4] Log C/Fe abundance ratio
relative Sun
88 A1 --- l_[C/Fe]c Limit flag on [C/Fe]c
90- 93 F4.2 [Sun] [C/Fe]c [0.6/5.4] Corrected Log C/Fe abundance ratio
95 A1 --- l_A(C) Limit flag on A(C)
97-100 F4.2 --- A(C) [5/9.4] Absolute Carbon abundance
= logεC
102-102 A1 --- l_[Ba/Fe] Limit flag on [Ba/Fe]
103-107 F5.2 [Sun] [Ba/Fe] [-3/3.5]? Log Ba/Fe I Abundance ratio
relative to Sun
109 A1 --- f_[Ba/Fe] Flag on [Ba/Fe] (3)
111 A1 --- l_[Eu/Fe] Limit flag on [Eu/Fe]
112-116 F5.2 [Sun] [Eu/Fe] [-0.5/4.5]? Log Eu/Fe I Abundance ratio
relative to Sun
118 A1 --- f_[Eu/Fe] Flag on [Eu/Fe] (3)
120-129 A10 --- Class Classification (Ba|A(C)) (4)
131-132 A2 --- Bin Binarity status code (5)
134 A1 --- f_Bin Flag on Bin (6)
136 A1 --- Out [x] Interesting outlier flag (7)
138-162 A25 --- Auth First author and year of the reference
164-182 A19 --- Bibcode ADS/SIMBAD bibcode of the reference
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Note (1): Stars in the overlapping regions: BD-01 2582 (I/II),
CS 22877-001 (II/III), CS 22960-053 (II/III), CS 29502-092 (II/III),
CS 29504-006 (I/II/III), CS 30314-067 (II/III), HE 0015+0048 (II/III),
HE 0102-1213 (II/III), HE 0146-1548 (II/III), HE 0430-1609 (I/II/III),
HE 1300-0641 (II/III), HE 1351-1049 (II/III), HE 1338-0052 (I/II/III),
HE 1506-0113 (II/III), HE 2133-1426 (I/III), HE 2208-1239 (I/II/III),
HE 2331-7155 (II/III), SDSS J1036+1212 (II/III),
SDSS J0212+0137 (I/III), SDSS J1422+0031 (I/II/III), and
SDSS J1613+5309 (I/III).
Note (2): Flag as follows:
f = CEMP-s stars with unusually low metallicities.
g = This star, HE 1105+0027, was mis-classified as an r-II star in
Hansen et al. (2015A&A...583A..49H 2015A&A...583A..49H), which showed this star is a single
star.
m = Hansen et al. (2016A&A...586A.160H 2016A&A...586A.160H) have reported
CS 29527-015 ([Ba/Fe]<+0.10) as a single CEMP-no star.
n = Hansen et al. (2016A&A...588A..37C 2016A&A...588A..37C) were able to classify this
star as a CEMP-no star based on non-detection of Ba lines; we did not
add this star to the classified stars due to the absence of [Ba/Fe].
However, our classification scheme based on A(C) is consistent with
their classification.
c = Flag added by CDS: HE 0103-0352 was very likely a misprint for
HE 0103-0357; corrected at CDS.
o = Declination sign of HE 1133-0555 corrected by CDS;
Declination of SDSS J0711+6702 corrected for +67 02 28.2;
SDSS J1137+2553 coordinates corrected for 11 37 23.26 +25 53 54.30
(taken from Bonifacio+, 2015, J/A+A/579/A28).
Note (3): Flag as follows:
k = This star has [Fe/H]< -5.05 and A(Ba)← 0.49,
so [Ba/Fe] cannot be determined.
l = This star has [Fe/H]< -7.8, [Ba/H]← 6.1,
and [Eu/H]< -2.9, so [Ba/Fe] and [Eu/Fe] cannot be determined.
Note (4): Sub-classification of a given star based first on the
[Ba/Fe] criterion, followed by its classification based on the
A(C) criterion described below. For instance, the notation (no|s)
means that the star was sub-classified as a CEMP-no star based on the
[Ba/Fe] criterion, but as a CEMP-s/rs star based on the A(C)
criterion. We note that precise sub-classification for these stars
(as either CEMP-s or CEMP-r/s) requires a [Eu/Fe] detection, which is
not presently available for all of the stars in our sample.
See Section 2 for more details.
Note (5): The binary status for CEMP-no stars and CEMP-s/rs are
from Hansen et al. (2016A&A...586A.160H 2016A&A...586A.160H) and
Hansen et al. (2016A&A...588A...3H 2016A&A...588A...3H),
respectively, unless otherwise indicated. Code as follows:
1 = single star;
2 = binary star;
2? = likely binary star.
Note (6): Flag as follows:
b = Binary status is from Preston & Sneden (2001AJ....122.1545P 2001AJ....122.1545P].
c = Binary status is from Thompson et al. (2008ApJ...677..556T 2008ApJ...677..556T],
recognized as a double-lined spectroscopic binary.
d = Binary status is from McClure & Woodsworth (1990ApJ...352..709M 1990ApJ...352..709M].
e = Binary status is from Placco et al. (2015, J/ApJ/812/109).
h = Binary status is from Jorissen et al. (2016, J/A+A/586/A158)
i = Binary status is from Spite et al. (2013A&A...552A.107S 2013A&A...552A.107S].
j = Binary status is from Dearborn et al. (1986ApJ...300..314D 1986ApJ...300..314D]
Note (7):
x = stars whose binary status does not meet with expectation given their
observed A(C) and/or [Ba/Fe], or with disparate values of A(C) and
[Ba/Fe].
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- Group Group type (G1)
5- 21 A17 --- Name Star designation
23 A1 --- l_[Fe/H] Limit flag on [Fe/H]
25- 29 F5.2 [Sun] [Fe/H] [-7.8/-2.6] Metallicity
31- 34 F4.2 --- A(C) [5.2/7.3] Absolute Carbon abundance (1)
36 A1 --- l_[Na/Fe] Limit flag on [Na/Fe]
38- 42 F5.2 [Sun] [Na/Fe] [-0.7/2.5]? Log Na/Fe Abundance ratio
43 A1 --- f_[Na/Fe] [a] Flag on [Na/Fe] (2)
45 A1 --- l_A(Na) Limit flag on A(Na)
47- 51 F5.2 --- A(Na) [0.5/4.4]? Absolute Na abundance (3)
52 A1 --- f_A(Na) [b] Flag on A(Na) (2)
54 A1 --- l_[Mg/Fe] Limit flag on [Mg/Fe]
56- 60 F5.2 [Sun] [Mg/Fe] [-0.07/3.4] Log Mg/Fe Abundance ratio
61 A1 --- f_[Mg/Fe] [ac] Flag on [Mg/Fe] (2)
63 A1 --- l_A(Mg) Limit flag on A(Mg)
65- 68 F4.2 --- A(Mg) [2.4/5.7] Absolute Mg abundance (3)
69 A1 --- f_A(Mg) [b] Flag on A(Mg) (2)
71- 94 A24 --- Auth First author and year of the reference
96-114 A19 --- BibCode ADS/SIMBAD bibcode of the reference
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Note (1): A(C) is based on the corrected carbon-abundance ratio, [C/Fe]c;
the listed references are the same as in Table 1.
Note (2): Flag as follows:
a = This star has only reported A(Na) and A(Mg). [Na/Fe] and [Mg/Fe] were
calculated based on the Asplund+ (2009ARA&A..47..481A 2009ARA&A..47..481A) solar abundance.
b = This star has only reported [Na/H]←5.7 and [Mg/H]=-4.45.
c = [Mg/Fe] was calculated based on the reported [Mg/H]-[Fe/H].
Note (3): A(Na) and A(Mg) are obtained based on the solar abundances of Na and
Mg from Asplund+ (2009ARA&A..47..481A 2009ARA&A..47..481A).
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Global notes:
Note (G1): Object group as follows:
III = Group III star ([Fe/H]←3.5, centered on A(C)∼6.8);
II = Group II star (metallicity range of -5.0≲[Fe/H]≲-2.5, and, in
contrast to the Group III stars, exhibit a clear dependence of
A(C) on [Fe/H]);
I = Group I star (as seen in figure 1, CEMP-no stars that fall into
neither of these groups, but are scattered throughout the region
primarily occupied by the CEMP-s/rs stars);
Unclassified = Unclassified CEMP Stars based on the [Ba/Fe] Criterion.
See section 3 for further explanations.
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History:
From electronic version of the journal
19-Apr-2017: Insert into VizieR
21-Jun-2018: Declination sign of HE1133-0555 corrected in table 1.
22-Jun-2018: SDSS J0711+6702 declination corrected in table 1;
SDSS J1137+2553 coordinates corrected in table 1
(taken from Bonifacio+, 2015, J/A+A/579/A28).
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 17-Mar-2017