J/A+A/621/A108 Radial velocity compilation for 45 CEMP-no stars (Arentsen+ 2019)
Binarity in CEMP-no stars: an indication of multiple formation pathways?
Arentsen A., Starkenburg E., Shetrone, M.D., Venn, K.A., Depagne E.,
McConnachie A.W.,
<Astron. Astrophys. 621, A108 (2019)>
=2019A&A...621A.108A 2019A&A...621A.108A (SIMBAD/NED BibCode)
ADC_Keywords: Stars, peculiar ; Binaries, spectroscopic
Keywords: stars: chemically peculiar - binaries: spectroscopic -
stars: AGB and post-AGB - Galaxy: halo - galaxies: formation
Abstract:
Carbon-enhanced metal-poor (CEMP) stars comprise a high percentage of
stars at the lowest metallicities. The stars in the CEMP-no
subcategory do not show any s-process enhancement and therefore cannot
easily be explained by transfer of carbon and s-process elements from
a binary AGB companion. We have performed radial velocity monitoring
of a sample of 22 CEMP-no stars to further study the role that
binarity plays in this type of CEMP star. We find four new binary
CEMP-no stars based on their radial velocity variations; this
significantly enlarges the population of known binaries to a total of
11. One of the new stars found to be in a binary system is HE
0107-5240, which is one of the most iron-poor stars known. This
supports the binary transfer model for the origin of the abundance
pattern of this star.We find a difference in binary fraction in our
sample that depends on the absolute carbon abundance, with a binary
fraction of 47 (+15/-14) % for stars with a higher absolute carbon
abundance and 18 (+14/-9) % for stars with a lower absolute carbon
abundance. This might imply a relation between a high carbon abundance
and the binarity of a metal-poor star. Although binarity does not
equate to mass transfer, there is a possibility that a CEMP-no star in
a binary system has been polluted, and care has to be taken in the
interpretation of their abundance patterns. We furthermore demonstrate
the potential of Gaia of discovering additional binary candidates.
Description:
(Heliocentric) Radial velocities for 45 CEMP-no stars are presented.
This work added 90 radial velocity measurements for 22 stars, derived
from CFHT ESPaDOnS and SALT HRS spectra. The other measurements are a
compilation from the literature or derived from ESO archive spectra.
For each of the stars we additionally compiled Teff, logg, [Fe/H],
[C/Fe], A(C), [Ba/Fe], [Mg/C] and a binarity flag.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tableb1.dat 90 45 List of 45 CEMP-no stars with multiple radial
velocity measurements
tableb2.dat 136 700 *Compilation of 710 radial velocity measurements
for 45 CEMP-no stars
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Note on tableb2.dat: we do not include Gaia DR2 radial velocities in this table
because they are averages over multiple measurements in time.
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See also:
J/A+A/490/769 : Yields from extremely metal-poor stars (Campbell+, 2008)
J/ApJ/788/180 : Very metal-poor stars in the Milky Way's halo (Carollo+, 2014)
J/A+A/574/A129 : The First CEMP star in the Sculptor dSph (Skuladottir+, 2015)
J/A+A/579/A28 : Abundances of 3 CEMP stars (Bonifacio+, 2015)
J/A+A/581/A22 : 67 CEMP-s stars model analysis (Abate+, 2015)
J/ApJ/812/109 : HST + Keck spectroscopy of bright CEMP-s stars (Placco+, 2015)
J/ApJ/814/121 : CASH project. III. The CEMP star HE0414-0343 (Hollek+, 2015)
J/ApJ/833/20 : Carbon-enhanced metal-poor (CEMP) star abundances (Yoon+ 2016)
J/A+A/586/A158 : Binary properties of CH and CEMP stars (Jorissen+, 2016)
J/A+A/606/A55 : Rotational mixing in CEMP-s stars (Matrozis+, 2017)
J/ApJS/228/19 : Exploring the SDSS data set. I. EMP + CV stars (Carbon+, 2017)
Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Name Star name (1)
17- 18 I2 --- o_RV Number of radial velocity measurements in
table C2 (full compilation)
20- 26 F7.2 km/s RVw Weighted average of o_RV radial velocities
28- 32 F5.2 km/s s_RV Standard deviation of o_RV radial velocities
34 A1 --- l_P(chi2) Limit flag on P(chi2)
35- 42 F8.6 --- P(chi2) ? Reduced chi square probability (p-value)
44- 45 A2 --- Bin Binary flag (2)
47- 50 I4 K Teff Effective temperature
52- 55 F4.2 --- logg Surface gravity
57 A1 --- l_[Fe/H] Limit flag on [Fe/H]
58- 62 F5.2 --- [Fe/H] ? Iron abundance
64 A1 --- l_[C/Fe] Limit flag on [C/Fe]
65- 68 F4.2 --- [C/Fe] Carbon to iron ratio (3)
71- 74 F4.2 --- A(C) Absolute carbon abundance (3)
76 A1 --- l_[Ba/Fe] Limit flag on [Ba/Fe]
77- 81 F5.2 --- [Ba/Fe] ? Barium to iron ratio
83- 87 F5.2 --- [Mg/C] ? Magnesium to carbon ratio (3)
89- 90 I2 --- Ref Reference for stellar parameters (4)
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Note (1): We adopted the dwarf solutions for HE 1201-1512 and SDSS J0140$2344
from the literature reference.
Note (2): Binary flag, as collected by Yoon et al. (2016ApJ...833...20Y 2016ApJ...833...20Y,
Cat. J/ApJ/833/20) and updated in this work, as follows:
1 = single
2 = binary
2? = binary ?
Note (3): Any abundance including carbon is corrected for evolutionary status,
as reported in Yoon et al. (2016ApJ...833...20Y 2016ApJ...833...20Y). Measurements of stars that
are not in the original compilation are marked by a * and have not been
corrected. However, all of these stars have logg>2.0, where the correction
is expected to be small.
Note (4): References are as follows:
1 = Ito et al. (2013ApJ...773...33I 2013ApJ...773...33I)
2 = Yong et al. (2013ApJ...762...26Y 2013ApJ...762...26Y)
3 = Jacobson et al. (2015ApJ...807..171J 2015ApJ...807..171J)
4 = Giridhar et al. (2001PASP..113..519G 2001PASP..113..519G)
5 = Roederer et al. (2014AJ....147..136R 2014AJ....147..136R)
6 = Placco et al. (2016ApJ...829L..24P 2016ApJ...829L..24P)
7 = Plez & Cohen (2005A&A...434.1117P 2005A&A...434.1117P)
8 = Christlieb et al. (2004A&A...428.1027C 2004A&A...428.1027C)
9 = Hansen et al. (2016A&A...586A.160H 2016A&A...586A.160H)
10 = Norris et al. (2007ApJ...670..774N 2007ApJ...670..774N)
11 = Barklem et al. (2005A&A...439..129B 2005A&A...439..129B)
12 = Frebel et al. (2008ApJ...684..588F 2008ApJ...684..588F)
13 = Cohen et al. (2013ApJ...778...56C 2013ApJ...778...56C)
14 = Placco et al. (2014ApJ...797...21P 2014ApJ...797...21P)
15 = Bonifacio et al. (2015A&A...579A..28B 2015A&A...579A..28B) and for magnesium
Caffau et al. (2011Natur.477...67C 2011Natur.477...67C)
16 = Bandyopadhyay et al. (2018ApJ...859..114B 2018ApJ...859..114B)
17 = Aoki et al. (2013AJ....145...13A 2013AJ....145...13A)
18 = Norris et al. (2010ApJ...723.1632N 2010ApJ...723.1632N)
19 = Bessell et al. (2015ApJ...806L..16B 2015ApJ...806L..16B) and for magnesium
Keller et al. (2014Natur.506..463K 2014Natur.506..463K)
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Byte-by-byte Description of file: tableb2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Name Star name
17- 25 F9.4 km/s HRV Heliocentric radial velocity
26 A1 --- --- [/]
27- 32 F6.2 km/s HRV2 ? Second heliocentric radial velocity
for SDSS 0929+0238 (1)
33 A1 --- --- [/]
34- 39 F6.2 km/s HRV3 ? Third heliocentric radial velocity
for SDSS 0929+0238 (1)
41- 46 F6.3 km/s e_HRV ?=- Radial velocity uncertainty
48- 65 F18.12 d HJD Heliocentric Julian date (HJD-2450000)
67-136 A70 --- r_RV Reference(s)
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Note (1): for SDSS 0929+0238, some HJDs have multiple RV measurements because
this star is a double (possible triple) lined binary system.
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Acknowledgements:
Anke Arentsen, aarentsen(at)aip.de
(End) Patricia Vannier [CDS] 13-Nov-2018