NUGRID STELLAR DATA SET. I. STELLAR YIELDS FROM H TO BI FOR STARS WITH METALLICITIES Z = 0.02 and Z = 0.01

Pignatari, M.; Herwig, Falk; Hirschi, Raphaël; Bennett, Michael; Rockefeller, Gabriel; Fryer, Chris L.; Timmes, F. X.; Ritter, Christian; Heger, Alexander; Jones, Samuel; Battino, U.; Dotter, Aaron; Trappitsch, R.; Diehl, Steven; Frischknecht, U.; Hungerford, Aimee; Magkotsios, Georgios; Travaglio, C.; Young, Patrick

doi:10.3847/0067-0049/225/2/24

Cited by 229 publications

(255 citation statements)

References 279 publications

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“…In fact, a higher amount of 12 C in the intershell leads to a higher abundance of 13 C, and subsequently a higher number of free neutrons. Full s-process models including this effect have been developed by Pignatari et al (2016) and Battino et al (2016).…”

Section: Current Models For the Formation Of 13 C Pocketsmentioning

confidence: 99%

Partial mixing and the formation of 13C pockets in AGB stars: effects on the s-process elements

Buntain

Doherty

Lugaro

et al. 2017

Monthly Notices of the Royal Astronomical Society

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The production of the elements heavier than iron via slow neutron captures (the s process) is a main feature of the contribution of asymptotic giant branch (AGB) stars of low mass (< 5 Msun) to the chemistry of the cosmos. However, our understanding of the main neutron source, the 13 C(α,n) 16 O reaction, is still incomplete. It is commonly assumed that in AGB stars mixing beyond convective borders drives the formation of 13 C pockets. However, there is no agreement on the nature of such mixing and free parameters are present. By means of a parametric model we investigate the impact of different mixing functions on the final s-process abundances in low-mass AGB models. Typically, changing the shape of the mixing function or the mass extent of the region affected by the mixing produce the same results. Variations in the relative abundance distribution of the three s-process peaks (Sr, Ba, and Pb) are generally within +/-0.2 dex, similar to the observational error bars. We conclude that other stellar uncertainties -the effect of rotation and of overshoot into the C-O core -play a more important role than the details of the mixing function. The exception is at low metallicity, where the Pb abundance is significantly affected. In relation to the composition observed in stardust SiC grains from AGB stars, the models are relatively close to the data only when assuming the most extreme variation in the mixing profile.

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Section: Current Models For the Formation Of 13 C Pocketsmentioning

confidence: 99%

Partial mixing and the formation of 13C pockets in AGB stars: effects on the s-process elements

Buntain

Doherty

Lugaro

et al. 2017

Monthly Notices of the Royal Astronomical Society

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“…Instead, one-zone simulations-although constituting a further simplification, allow studying the nucleosynthesis that may be possible in this event in isolation. The dynamic NuGrid network includes as required up to 5234 isotopes with associated rates from JINA Reaclib V1.1 (Cyburt et al 2010) and other additional sources (see Pignatari et al 2016). The general strategy is to approximate the nucleosynthesis through a series of three one-zone calculations which start with H burning followed by He burning and finally, we add in the last step a small amount of H to the partially completed He-burning nucleosynthesis calculation to estimate the nucleosynthesis due to H ingestion.…”

Section: Nucleosynthesis Calculationsmentioning

confidence: 99%

Pop III i-process nucleosynthesis and the elemental abundances of SMSS J0313−6708 and the most iron-poor stars

Clarkson

Herwig

Pignatari

2017

Monthly Notices of the Royal Astronomical Society: Letters

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We have investigated a highly energetic H-ingestion event during shell He burning leading to H-burning luminosities of log(L H /L ) ∼ 13 in a 45M Pop III massive stellar model. In order to track the nucleosynthesis which may occur in such an event, we run a series of single-zone nucleosynthesis models for typical conditions found in the stellar evolution model. Such nucleosynthesis conditions may lead to i-process neutron densities of up to ∼ 10 13 cm −3 . The resulting simulation abundance pattern, where Mg comes from He burning and Ca from the i process, agrees with the general observed pattern of the most iron-poor star currently known, SMSS J031300.36-670839.3. However, Na is also efficiently produced in these i process conditions, and the prediction exceeds observations by ∼ 2.5dex. While this probably rules out this model for SMSS J031300.36-670839.3, the typical i-process signature of combined He burning and i process of higher than solar [Na/Mg], [Mg/Al] and low [Ca/Mg] is reproducing abundance features of the two next most iron-poor stars HE 1017-5240 and HE 1327-2326 very well. The i process does not reach Fe which would have to come from a low level of additional enrichment. i process in hyper-metal poor or Pop III massive stars may be able to explain certain abundance patterns observed in some of the most-metal poor CEMP-no stars.

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“…To be rigorous in our comparisons, we combine OMEGA with the Markov Chain Monte Carlo (MCMC) code described in ForemanMackey et al (2013) to derive the set of parameters for each model that best fits the observed stellar abundances in Sculptor. All numerical predictions and observational data shown in this work are normalized to the solar composition found in Grevesse & Noels (1993), which is the one adopted in NuGrid models (see Pignatari et al 2016).…”

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confidence: 99%

“…Our motivation is to bridge the fields of nuclear physics, stellar evolution, galaxy evolution, cosmological structure formation, and modern statistical methods. This framework consists of a chain of models that so far includes the NuGrid stellar evolution models which use the JINA ReacLib nuclear reaction network (Pignatari et al 2016;Ritter et al in prep. ), the SYGMA (Stellar Yields for Galactic Modeling Applications, Ritter et al in prep.)…”

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confidence: 99%

The Impact of Modeling Assumptions in Galactic Chemical Evolution Models

Côté

O’Shea

Ritter

et al. 2017

ApJ

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We use the OMEGA galactic chemical evolution code to investigate how the assumptions used for the treatment of galactic inflows and outflows impact numerical predictions. The goal is to determine how our capacity to reproduce the chemical evolution trends of a galaxy is affected by the choice of implementation used to include those physical processes. In pursuit of this goal, we experiment with three different prescriptions for galactic inflows and outflows and use OMEGA within a Markov Chain Monte Carlo code to recover the set of input parameters that best reproduces the chemical evolution of nine elements in the dwarf spheroidal galaxy Sculptor. This provides a consistent framework for comparing the best-fit solutions generated by our different models. Despite their different degrees of intended physical realism, we found that all three prescriptions can reproduce in an almost identical way the stellar abundance trends observed in Sculptor. This result supports the similar conclusions originally claimed by Romano & Starkenburg (2013) for Sculptor. While the three models have the same capacity to fit the data, the best values recovered for the parameters controlling the number of Type Ia supernovae and the strength of galactic outflows, are substantially different and in fact mutually exclusive from one model to another. For the purpose of understanding how a galaxy evolves, we conclude that only reproducing the evolution of a limited number of elements is insufficient and can lead to misleading conclusions. More elements or additional constraints such as the galaxy's star formation efficiency and the gas fraction are needed in order to break the degeneracy between the different modeling assumptions. Our results show that the successes and failures of chemical evolution models are predominantly driven by the input stellar yields, rather than by the complexity of the galaxy model itself. Simple models such as OMEGA are therefore sufficient to test and validate stellar yields. OMEGA is part of the NuGrid chemical evolution package and is publicly available online at http://nugrid.github.io/NuPyCEE.

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NUGRID STELLAR DATA SET. I. STELLAR YIELDS FROM H TO BI FOR STARS WITH METALLICITIES Z = 0.02 and Z = 0.01

Cited by 229 publications

References 279 publications

Partial mixing and the formation of 13C pockets in AGB stars: effects on the s-process elements

Partial mixing and the formation of 13C pockets in AGB stars: effects on the s-process elements

Pop III i-process nucleosynthesis and the elemental abundances of SMSS J0313−6708 and the most iron-poor stars

The Impact of Modeling Assumptions in Galactic Chemical Evolution Models

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