J/A+A/668/A100 Yields Z=1e-6-1e-10 intermediate-mass stars (Gil-Pons+, 2022)
Nucleosynthetic yields of intermediate-mass primordial to extremely metal-poor
stars.
Gil-Pons P., Doherty C.L., Campbell S.W., Gutierrez J.
<Astron. Astrophys. 668, A100 (2022)>
=2022A&A...668A.100G 2022A&A...668A.100G (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: Population II -
stars: evolution
Abstract:
Stellar models and nucleosynthetic yields of primordial to extremely
metal-poor (EMP) stars are crucial to interpret the surface abundances
of the most metal-poor stars observed, and ultimately, to better
understand the earliest stellar populations. In addition, they are key
ingredients of Galactic chemical evolution models.
We aim to better characterize the evolution and fates, and determine
updated nucleosynthetic yields of intermediate-mass stars between
primordial and EMP metallicity (Z=10-10, 10-8, 10-7, 10-6,
and 10-5). We also probe uncertainties in the nucleosynthesis of
the oldest intermediate-mass stars, namely those related to the
treatment of convection and convective boundaries, and those related
to wind prescriptions during the Asymptotic Giant Branch (AGB) phase.
We analyse the evolution of models from their main sequence, through
the thermally-pulsing AGB (TP-AGB), till the latest stages of their
evolution, using the Monash-Mount Stromlo stellar evolution code
MONSTAR. Results are post-processed with the code
MONSOON, which allows the determination of the
nucleosynthetic yields of 77 species up to 62Ni. By comparing to
similar calculations existing in the literature, we inspect the
effects of input physics on the nucleosynthesis of EMP models.
From the evolutionary point of view, as reported in former works, we
identify proton ingestion episodes (PIE) in our lowest-mass lowest-
metallicity models. Models of Z=10-10 and Z=10-8 in a narrow
initial mass range around 5M☉ experience the cessation of
thermal pulses, and their final fates as supernovae I1/2 (SNeI1/2)
cannot be discarded, however, the initial mass range of models
eventually leading to the formation of SNe I1/2 and electron-capture
SNe is considerably reduced compared to former works. All the models
of initial mass ≳6-7M☉ experience a corrosive second dredge-up
and, analogously to those experiencing PIEs, undergo significant metal
enrichment in their envelopes. The associated increase in their
opacities allows them to develop a solar-like TP-AGB or TP-super-AGB,
TP-(S)AGB phase and ultimately become white dwarfs. Except those
undergoing the cessation of thermal pulses, all our models show the
nucleosynthetic signatures of both efficient third dredge-up and
hot-bottom burning, with the activation of the NeNa-cycle and the
MgAlSi-chains. This leads to the creation of vast amounts of CNO, with
typical [N/Fe]~≳4), and the characteristic abundance signature
[N/Fe]~≳[C/Fe]~≳[O/Fe]. Our nucleosynthetic yields present dramatic
differences with respect to recent results existing in the literature
for intermediate-mass models of similar metallicities. The reason for
these discrepancies lay in the poorly known input physics related to
stellar winds and, above all, the treatment of convection and
convective boundaries.
Description:
We tabulate nucleosynthetic yields and additional related information
for intermediate-mass stars of metallicity Z=10-10, 10-8, 10-7
and 10-6. 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), with eta parameter equal
to 0.02.
Postprocessing was calculated with the code MONSOON developed at
Monash University (Cannon, 1993MNRAS.253..817C 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:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
z1em06.dat 128 462 Yields computed for models of Z=1e-6
z1em07.dat 128 539 Yields computed for models of Z=1e-7
z1em08.dat 128 539 Yields computed for models of Z=1e-8
z1em10.dat 128 539 Yields computed for models of Z=1e-10
--------------------------------------------------------------------------------
See also:
J/A+A/490/769 : Yields from extremely metal-poor stars (Campbell+, 2008)
J/A+A/645/A10 : Yields for Z=1e-5 intermediate-mass stars (Gil-Pons+, 2021)
Byte-by-byte Description of file: z1em06.dat z1em07.dat z1em08.dat z1em10.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 E8.2 --- Z Metallicity
10- 14 F5.1 Msun Mini Initial mass
16- 21 A6 --- Species Species i
23- 26 I4 --- A(i) Atomic mass of i
28- 43 E16.8 Msun Yield(i) Yield of i
45- 60 E16.8 Msun Meject(i) Ejected mass of i
62- 77 E16.8 Msun Mini(i) Initial mass of i, M0(i)
79- 94 E16.8 --- <X(i)> Average abundance of i in the wind
96-111 E16.8 --- X0(i) Initial abundance of i
113-128 E16.8 --- log(<X(i)>/X0(i)) log10 of production factor of i
--------------------------------------------------------------------------------
Acknowledgements:
Pilar Gil-Pons, pilar.gil(at)upc.edu
We thank the anonymous referee for their useful comments and
clarifications. This work was supported by the Spanish project PID
2019- 109363GB-100, and by the German Deutsche Forschungsgemeinschaft,
DFG project number Ts 17/2-1. S.W.C. acknowledges federal funding from
the Aus- tralian Research Council through a Future Fellowship
(FT160100046) and Dis- covery Project (DP190102431). This research was
supported by use of the Nec- tar Research Cloud, a collaborative
Australian research platform supported by the National Collaborative
Research Infrastructure Strategy (NCRIS).
(End) Patricia Vannier [CDS] 14-Sep-2022