Production of Light-Element Primary Process Nuclei in Neutrino-Driven Winds

Arcones, Almudena; Montes, F.

doi:10.1088/0004-637x/731/1/5

Cited by 197 publications

(219 citation statements)

References 72 publications

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“…The work of Winteler et al (2012) showed that magneto-rotational corecollapse SN jets can reproduce the solar abundance pattern for 120 < A < 210. Moreover, Arcones & Montes (2011) argue that neutrino-driven winds, either proton-or neutron-rich, stemming from core-collapse SNe can create nuclei in the range 65 < A < 115. Despite the different sites suggested, both studies illustrated the importance of knowing Y e .…”

Section: Discussion Of Yield Predictionsmentioning

confidence: 99%

“…Nevertheless, the conditions are still poorly constrained. A number of sites have been suggested: neutron star mergers (Freiburghaus et al 1999b;Goriely et al 2011a,b;Wanajo & Janka 2012), massive core-collapse supernovae (SNe) (Wasserburg & Qian 2000;Argast et al 2004), neutrino-driven winds from core-collapse SNe (Duncan et al 1986;Meyer 1993;Takahashi et al 1994;Woosley et al 1994;Freiburghaus et al 1999a;Wanajo et al 2001;Farouqi et al 2009Farouqi et al , 2010Arcones & Montes 2011), low-mass SNe from collapsing O-Ne-Mg cores (Wanajo et al 2003; or iron cores Sumiyoshi et al 2001). However, no consensus on the formation site has been reached.…”

Section: Introductionmentioning

confidence: 99%

“…Some of the proposed processes are the lighter element primary process (LEPP, Travaglio et al 2004;Arcones & Montes 2011), the weak r-process (Kratz et al 2007;Montes et al 2007;Farouqi et al 2009;Wanajo et al 2011), the νp-process (Fröhlich et al 2006), and several more processes and comparisons, which can be found in Cowan et al (2001), Qian & Wasserburg (2001), and Sneden et al (2003). These processes can be considered when attempting to explain the abundances of the lighter heavy elements, which have been found to deviate from the solar-scaled r-process pattern 2 .…”

Section: Introductionmentioning

confidence: 99%

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Silver and palladium help unveil the nature of a second r-process

Hansen

Primas

Hartman

et al. 2012

A&A

145

204

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Context. The rapid neutron-capture process, which created about half of the heaviest elements in the solar system, is believed to have been unique. Many recent studies have shown that this uniqueness is not true for the formation of lighter elements, in particular those in the atomic number range 38 < Z < 48. Among these, palladium (Pd) and especially silver (Ag) are expected to be key indicators of a possible second r-process, but until recently they have been studied only in a few stars. We therefore target Pd and Ag in a large sample of stars and compare these abundances to those of Sr, Y, Zr, Ba, and Eu produced by the slow (s-) and rapid (r-) neutron-capture processes. Hereby we investigate the nature of the formation process of Ag and Pd. Aims. We study the abundances of seven elements (Sr, Y, Zr, Pd, Ag, Ba, and Eu) to gain insight into the formation process of the elements and explore in depth the nature of the second r-process. Methods. By adopting a homogeneous one-dimensional local thermodynamic equilibrium (1D LTE) analysis of 71 stars, we derive stellar abundances using the spectral synthesis code MOOG, and the MARCS model atmospheres. We calculate abundance ratio trends and compare the derived abundances to site-dependent yield predictions (low-mass O-Ne-Mg core-collapse supernovae and parametrised high-entropy winds), to extract characteristics of the second r-process. Results. The seven elements are tracers of different (neutron-capture) processes, which in turn allows us to constrain the formation process(es) of Pd and Ag. The abundance ratios of the heavy elements are found to be correlated and anti-correlated. These trends lead to clear indications that a second/weak r-process, is responsible for the formation of Pd and Ag. On the basis of the comparison to the model predictions, we find that the conditions under which this process takes place differ from those for the main r-process in needing lower neutron number densities, lower neutron-to-seed ratios, and lower entropies, and/or higher electron abundances. Conclusions. Our analysis confirms that Pd and Ag form via a rapid neutron-capture process that differs from the main r-process, the main and weak s-processes, and charged particle freeze-outs. We find that this process is efficiently working down to the lowest metallicity sampled by our analysis ([Fe/H] = −3.3). Our results may indicate that a combination of these explosive sites is needed to explain the variety in the observationally derived abundance patterns.

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Section: Discussion Of Yield Predictionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Silver and palladium help unveil the nature of a second r-process

Hansen

Primas

Hartman

et al. 2012

A&A

145

204

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“…Freiburghaus et al 1999;Goriely et al 2011), while the weak r-process may come from neutrino-driven winds (e.g. Arcones & Montes 2011), or electron-capturing supernovae (SNe) collapsing on O-Mg-Ne cores (Wanajo et al 2011). A p-process contribution could also be expected from supernova winds that would facilitate for example a νp-process (Fröhlich et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Stellar abundances and presolar grains trace the nucleosynthetic origin of molybdenum and ruthenium

Hansen¹,

Andersen

Christlieb³

2014

A&A

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This work presents a large consistent study of molybdenum (Mo) and ruthenium (Ru) abundances in the Milky Way. These two elements are important nucleosynthetic diagnostics. In our sample of 71 Galactic metal-poor field stars, we detect Ru and/or Mo in 52 of these (59 including upper limits). The sample consists of high-resolution, high signal-to-noise spectra covering both dwarfs and giants from [Fe/H] = −0.63 down to −3.16. Thus we provide information on the behaviour of Mo I and Ru I at higher and lower metallicity than is currently known. In this sample we find a wide spread in the Mo and Ru abundances, which is typical of heavy elements. We confirm earlier findings of Mo enhanced stars around [Fe/H] = −1.5 and add ∼15 stars both dwarfs and giants with normal (<0.3 dex) Mo and Ru abundances, as well as more than 15 Mo and Ru enhanced (>0.5 dex) stars to the currently known stellar sample. This indicates that several formation processes, in addition to high entropy winds, can be responsible for the formation of elements like Mo and Ru. We trace the formation processes by comparing Mo and Ru to elements (Sr, Zr, Pd, Ag, Ba, and Eu) with known formation processes. Based on how tight the two elements correlate with each other, we are able to distinguish if they share a common formation process and how important this contribution is to the element abundance. We find clear indications of contributions from several different formation processes, namely the p-process, and the slow (s-), and rapid (r-) neutron-capture processes. From these correlations we find that Mo is a highly convolved element that receives contributions from both the s-process and the p-process and less from the main and weak r-processes, whereas Ru is mainly formed by the weak r-process as is silver. We also compare our absolute elemental stellar abundances to relative isotopic abundances of presolar grains extracted from meteorites. Their isotopic abundances can be directly linked to the formation process (e.g. r-only isotopes) providing a unique comparison between observationally derived abundances and the nuclear formation process. The comparison to abundances in presolar grains shows that the r-/s-process ratios from the presolar grains match the total elemental chemical composition derived from metal-poor halo stars with [Fe/H] around −1.5 to −1.1 dex. This indicates that both grains and stars around and above [Fe/H] = −1.5 are equally (well) mixed and therefore do not support a heterogeneous presolar nebula. An inhomogeneous interstellar medium (ISM) should only be expected at lower metallicities. Our data, combined with the abundance ratios of presolar grains, could indicate that the AGB yields are less efficiently mixed into stars than into presolar grains. Finally, we detect traces of s-process material at [Fe/H] = −1.5, indicating that this process is at work at this and probably at even lower metallicity.

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“…The following evolution of the composition is calculated within a full reaction network [10] which includes 4053 nuclei from H to Hf including both neutron-and proton-rich isotopes [5]. Experimental reaction rates [2] are included when available.…”

Section: Methodsmentioning

confidence: 99%

Nucleosynthesis of Mo in neutrino-driven winds

Bliss¹,

Arcones²

2015

Proceedings of XIII Nuclei in the Cosmos — PoS(NIC XIII)

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Neutrino-driven winds that follow core-collapse supernovae are an exciting astrophysical site for the production of heavy elements. Although hydrodynamical simulations show that the conditions in the wind are not extreme enough for a r-process up to uranium, neutrino-driven winds may be the astrophysical site where lighter heavy elements between Sr an Ag are produced, either by the weak r-process or by the νp-process. However, it is still not clear if the conditions in the wind are slightly neutron-rich or proton-rich. Therefore, we investigate the nucleosynthesis in the wind for neutron-and proton-rich conditions and systematically explore the impact of wind parameters on abundances. Here we focus on molybdenum that has raised attention because several astrophysical scenarios failed to reproduce the solar system (SoS) abundance ratio of 92

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Production of Light-Element Primary Process Nuclei in Neutrino-Driven Winds

Cited by 197 publications

References 72 publications

Silver and palladium help unveil the nature of a second r-process

Silver and palladium help unveil the nature of a second r-process

Stellar abundances and presolar grains trace the nucleosynthetic origin of molybdenum and ruthenium

Nucleosynthesis of Mo in neutrino-driven winds

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