J/A+A/645/A10 Yields for Z=1e-5 intermediate-mass stars (Gil-Pons+, 2021)
Nucleosynthetic yields of Z=10-5 intermediate-mass stars.
Gil-Pons P., Doherty C.L., Gutierrez J., Campbell S.W., Siess L.,
Lattanzio J.C.
<Astron. Astrophys. 645, A10 (2021)>
=2021A&A...645A..10G 2021A&A...645A..10G (SIMBAD/NED BibCode)
ADC_Keywords: Models, evolutionary ; Stars, carbon ; Stars, metal-deficient ;
Stars, population II ; Abundances
Keywords: stars: abundances - stars: AGB and post-AGB - stars: evolution -
stars: Population II
Abstract:
Observed abundances of extremely metal-poor (EMP) stars in the Halo
hold clues for the understanding of the ancient universe. Interpreting
these clues requires theoretical stellar models at the low-Z regime.
We provide the nucleosynthetic yields of intermediate-mass Z=10-5
stars between 3 and 7.5M☉, and quantify the effects of the
uncertain wind rates. We expect these yields can be eventually used to
assess the contribution to the chemical inventory of the early
universe, and to help interpret abundances of selected C-enhanced EMP
stars. By comparing our models and other existing in the literature,
we explore evolutionary and nucleosynthetic trends with wind
prescriptions and with initial metallicity. We compare our results to
observations of CEMP-s stars belonging to the Halo. The yields of
intermediate-mass EMP stars reflect the effects of very deep second
dredge-up (for the most massive models), superimposed with the
combined signatures of hot-bottom burning and third dredge-up. We
confirm the reported trend that models with initial metallicity
Zini≤0.001 give positive yields of 12C, 15N, 16O, and 26Mg.
The 20Ne, 21Ne, and 24Mg yields, which were reported to be
negative at Zini=0.0001, become positive for Z=10-5. The results
using two different prescriptions for mass-loss rates differ widely in
terms of the duration of the thermally-pulsing (Super) AGB phase,
overall efficiency of the third dredge-up episode, and nucleosynthetic
yields. The most efficient of the standard wind rates frequently used
in the literature seems to favour agreement between our yield results
and observational data. Regardless of the wind prescription, all our
models become N-enhanced EMP stars.
Description:
We tabulate nucleosynthetic yields and additional related information
for intermediate-mass stars of metallicity Z=0.00001. These yields are
the result of postprocessing of structure evolution obtained with
MONSTAR (Monash and Mount Stromlo stellar evolution code). See Frost &
Lattanzio, 1996ApJ...473..383F 1996ApJ...473..383F, Campbell & Lattanzio,
2008A&A...490..769C 2008A&A...490..769C, Cat. J/A+A/490/769, and Gil-Pons et al.
(2018PASA...35...38G 2018PASA...35...38G). Interior stellar opacities are from Iglesias &
Rogers (1996ApJ...464..943I 1996ApJ...464..943I). Variable-composition low-temperature
opacity tables are from Lederer & Aringer (2009A&A...494..403L 2009A&A...494..403L, Cat.
J/A+A/494/403) and Marigo & Aringer (2009A&A...508.1539M 2009A&A...508.1539M). Initial
composition was solar scaled as in Grevesse & Noels
(1993PhST...47..133G 1993PhST...47..133G). Stellar wind prescriptions are from Bloecker,
1995A&A...297..727B 1995A&A...297..727B (Blo95) and from Vassiliadis and Wood,
1993ApJ...413..641V 1993ApJ...413..641V (VW93).
Postprocessing was calculated with the code MONSOON developed at
Monash University (Cannon, 1993MNRAS,253,,817C; Lugaro et al.,
2004ApJ...615..934L 2004ApJ...615..934L; Doherty et al., 2014MNRAS.437..195D 2014MNRAS.437..195D). Nuclear
reaction rates are mostly from the JINA reaction library (Cyburt et
al., 2010ApJS..189..240C 2010ApJS..189..240C). p-captures for the NeNa-cycle and MgAl
chain are from Iliadis et al. (2001ApJS..134..151I 2001ApJS..134..151I), p-captures on
22Ne are from Hale et al. (2002PhRvC..65a5801H 2002PhRvC..65a5801H, alpha-captures on
22Ne are from Karakas et al. (2006ApJ...643..471K 2006ApJ...643..471K), and p-captures
on 23Na are from Hale et al. (2004PhRvC..70d5802H 2004PhRvC..70d5802H. The version of
MONSOON used for the present work includes 77 species, up to 32S and
Fe-peak elements. Additionally, it includes a 'g' particle (Lugaro
et al., 2004ApJ...615..934L 2004ApJ...615..934L), which is a proxy for s-process elements.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
z1em5bl.dat 118 616 Yields computed with wind prescription by
Bloecker (1995A&A...297..727B 1995A&A...297..727B)
z1em5vw.dat 118 385 Yields computed with wind prescription by
Vassiliadis and Wood (1993ApJ...413..641V 1993ApJ...413..641V)
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See also:
J/A+A/490/769 : Yields from extremely metal-poor stars (Campbell+, 2008)
Byte-by-byte Description of file: z1em5bl.dat z1em5vw.dat
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Bytes Format Units Label Explanations
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1- 7 E7.1 --- Z Metallicity
9- 11 F3.1 Msun Mini Initial mass
13- 17 A5 --- Wind Wind prescription
19- 22 F4.2 --- eta ? Wind prescription parameter
(only for z1em5bl.dat file)
24- 27 A4 --- Species Species i
29- 30 I2 --- A(i) Atomic mass of i
32- 45 E14.7 Msun Yield(i) Yield of i
47- 60 E14.7 Msun Meject(i) Ejected mass of i
62- 74 E13.7 Msun Mini(i) Initial mass of i, M0(i) (Msun)
76- 89 E14.7 --- <X(i)> Average abundance of i in the wind
91-103 E13.7 --- X0(i) Initial abundance of i
105-118 E14.7 [-] log(<X(i)>/X0(i)) log10 of production factor of i
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Acknowledgements:
Pilar Gil-Pons, pilar.gil(at)upc.edu
Part of this work was supported by the Spanish project
PID2019-109363GB-100, and by the German Deutsche
Forschungsgemeinschaft, DFG project number Ts 17/2-1.
(End) Patricia Vannier [CDS] 12-Dec-2020