J/ApJ/814/121 CASH project. III. The CEMP star HE0414-0343 (Hollek+, 2015)
The Chemical Abundances of Stars in the Halo (CASH) Project.
III. A new classification scheme for carbon-enhanced metal-poor stars with
s-process element enhancement.
Hollek J.K., Frebel A., Placco V.M., Karakas A.I., Shetrone M., Sneden C.,
Christlieb N.
<Astrophys. J., 814, 121 (2015)>
=2015ApJ...814..121H 2015ApJ...814..121H (SIMBAD/NED BibCode)
ADC_Keywords: Abundances ; Equivalent widths ; Stars, giant ;
Stars, metal-deficient
Keywords: Galaxy: halo; stars: abundances; stars: atmospheres;
stars: Population II
Abstract:
We present a detailed abundance analysis of 23 elements for a newly
discovered carbon-enhanced metal-poor (CEMP) star, HE0414-0343, from
the Chemical Abundances of Stars in the Halo Project. Its
spectroscopic stellar parameters are Teff=4863K, logg=1.25,
ξ=2.20km/s, and [Fe/H]=-2.24. Radial velocity measurements covering
seven years indicate HE 0414-0343 to be a binary. HE0414-0343 has
[C/Fe]=1.44 and is strongly enhanced in neutron-capture elements but
its abundances cannot be reproduced by a solar-type s-process pattern
alone. Traditionally, it could be classified as a "CEMP-r/s" star.
Based on abundance comparisons with asymptotic giant branch (AGB) star
nucleosynthesis models, we suggest a new physically motivated origin
and classification scheme for CEMP-s stars and the still poorly
understood CEMP-r/s. The new scheme describes a continuous transition
between these two so-far distinctly treated subgroups: CEMP-sA,
CEMP-sB, and CEMP-sC. Possible causes for a continuous transition
include the number of thermal pulses the AGB companion underwent, the
effect of different AGB star masses on their nucleosynthetic yields,
and physics that is not well approximated in 1D stellar models such as
proton ingestion episodes and rotation. Based on a set of detailed AGB
models, we suggest the abundance signature of HE 0414-0343 to have
arisen from a >1.3M☉ mass AGB star and a late-time mass transfer
that transformed HE 0414-0343 into a CEMP-sC star. We also find that
the [Y/Ba] ratio well parametrizes the classification and can thus be
used to easily classify any future such stars.
Description:
Four separate spectra were obtained for HE 0414-0343 between 2004 and
2011. A medium-resolution spectrum was observed in 2004 September as
part of the the Hamburg/ESO BMPS Sample (Frebel et al. 2006,
J/ApJ/652/1585; R∼2000). A high-resolution spectrum was obtained with
MIKE instrument at the Magellan-Clay Telescope at Las Campanas
Observator in 2006 September (R∼35000 in the blue). In 2008 October,
HE 0414-0343 was observed as part of the CASH project with the
fiber-fed High Resolution Spectrograph on the HET at McDonald
Observatory (R∼15000). The highest resolution spectrum, taken in March
2011, was also obtained using MIKE on the Magellan-Clay Telescope
(R∼56000 at 4900Å and ∼37000 at 5900Å)
Objects:
---------------------------------------------------------
RA (ICRS) DE Designation(s)
---------------------------------------------------------
04 17 16.4 -03 36 31 HE 0414-0343 = TYC 4729-1290-1
---------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 46 250 Equivalent widths and abundances
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See also:
J/A+A/586/A158 : Binary properties of CH and CEMP stars (Jorissen+, 2016)
J/A+A/581/A22 : 67 CEMP-s stars model analysis (Abate+, 2015)
J/A+A/579/A28 : Abundances of 3 CEMP stars (Bonifacio+, 2015)
J/ApJ/812/109 : HST + Keck spectroscopy of bright CEMP-s stars (Placco+, 2015)
J/ApJS/211/5 : Improved line data for the Swan system 12C13C (Ram+, 2014)
J/ApJ/769/57 : Equivalent widths of metal-poor stars (Frebel+, 2013)
J/MNRAS/418/284 : s-process in low-metallicity stars. II. (Bisterzo+, 2011)
J/ApJ/742/54 : CASH project II. 14 extremely metal-poor stars (Hollek+, 2011)
J/AJ/141/175 : Abundances in M15 RGB/RHB stars (Sobeck+, 2011)
J/MNRAS/403/1413 : Updated stellar yields from AGB models (Karakas, 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/A+A/484/721 : HES survey. IV. Candidate metal-poor stars (Christlieb+, 2008)
J/ApJ/655/492 : Equivalent widths of 26 metal-poor stars (Aoki+, 2007)
J/ApJ/652/1585 : Bright metal-poor stars from HES survey (Frebel+, 2006)
J/ApJ/617/1091 : La and Eu abundances in 85 stars (Simmerer+, 2004)
J/A+A/416/1117 : Abundances in the early Galaxy (Cayrel+, 2004)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- Species Species identifier
13- 19 F7.2 0.1nm lambda [3464.4/6767.8]? Wavelength; Angstroms
21- 24 F4.2 eV ExPot [0/4.5]? Excitation potential
26- 30 F5.2 [-] log(gf) [-5.7/0.7]? Log oscillator strength
32- 36 F5.1 10-13m EW [12.2/240.5]? Equivalent width; milliAngstroms
38 A1 --- f_EW [S] S=Obtained from spectrum synthesis
40- 44 F5.2 [-] logAbd [-0.5/7.7] Log epsilon(X)
46 A1 --- f_logAbd [a] Flag on logAbd (2)
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Note (2):
a = The C12/C13 value is a ratio and not a logAbd value.
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History:
From electronic version of the journal
References:
Roederer et al. Paper I. 2008ApJ...679.1549R 2008ApJ...679.1549R Cat. J/ApJ/679/1549
Hollek et al. Paper II. 2011ApJ...742...54H 2011ApJ...742...54H Cat. J/ApJ/742/54
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 02-Mar-2016