r-Process elements from magnetorotational hypernovae

Yong, David; Costa, G. S. Da; Bessell, M. S.; Chiti, Anirudh; Frebel, Anna; Lind, Karin; Mackey, A. D.; Nordlander, Thomas; Asplund, Martin; Casey, Andrew R.; Marino, A.; Murphy, Simon J.; Schmidt, B. P.

doi:10.1038/s41586-021-03611-2

Cited by 59 publications

(53 citation statements)

References 56 publications

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“…The abundances of this object have also been reported by Li et al (2015b) and Mardini et al (2020). Very recently, Yong et al (2021b) reported the discovery of an r-II star with [Fe/ H] = −3.5, for which they suggest a magnetorotational HN as the progenitor, taking the long delay time expected for binary neutron star merger events into consideration. The lowmatallicity tail of the metallicity distribution of r-II stars would be a key to constraining the origin of the r-process in the early Universe.…”

Section: Eu-rich Starssupporting

confidence: 67%

Four-hundred Very Metal-poor Stars Studied with LAMOST and Subaru. II. Elemental Abundances

Aoki

Matsuno

et al. 2022

ApJ

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We present homogeneous abundance analysis of over 20 elements for 385 very metal-poor (VMP) stars based on the LAMOST survey and follow-up observations with the Subaru Telescope. It is the largest high-resolution VMP sample (including 363 new objects) studied by a single program, and the first attempt to accurately determine evolutionary stages for such a large sample based on Gaia parallaxes. The sample covers a wide metallicity range from [Fe/H] ≲ −1.7 down to [Fe/H] ∼ −4.3, including over 110 objects with [Fe/H] ≤ −3.0. The expanded coverage in evolutionary status makes it possible to define the abundance trends respectively for giants and turnoff stars. The newly obtained abundance data confirm most abundance trends found by previous studies, but also provide useful updates and new samples of outliers. The Li plateau is seen in main-sequence turnoff stars with −2.5 < [Fe/H] < −1.7 in our sample, whereas the average Li abundance is clearly lower at lower metallicity. Mg, Si, and Ca are overabundant with respect to Fe, showing decreasing trend with increasing metallicity. Comparisons with chemical evolution models indicate that the overabundance of Ti, Sc, and Co are not well reproduced by current theoretical predictions. Correlations are seen between Sc and α-elements, while Zn shows a detectable correlation only with Ti but not with other α-elements. The fraction of carbon-enhanced stars ([C/Fe] > 0.7) is in the range of 20%–30% for turnoff stars depending on the treatment of objects for which C abundance is not determined, which is much higher than that in giants (∼8%). Twelve Mg-poor stars ([Mg/Fe] < 0.0) have been identified in a wide metallicity range from [Fe/H] ∼ −3.8 through −1.7. Twelve Eu-rich stars ([Eu/Fe] > 1.0) have been discovered in −3.4 < [Fe/H] < −2.0, enlarging the sample of r-process-enhanced stars with relatively high metallicity.

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Section: Eu-rich Starssupporting

confidence: 67%

Four-hundred Very Metal-poor Stars Studied with LAMOST and Subaru. II. Elemental Abundances

Aoki

Matsuno

et al. 2022

ApJ

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“…Sequences of models can follow the evolution of the merger event from 3D full general relativistic simulations of the actual merging [297,298], through the development of multiple types of outflows [299] with their individual r-process nucleosynthesis contributions [300,301], all the way to the atomic physics models to predict the electromagnetic kilonova signature [302,303,304] and spectral features of r-process elements [214]. Supernova r-process models involving collapsars [305,306], neutrino driven winds [307], magnetic field driven jets [308,309,310], and hadron quark phase transitions [311] have also advanced considerably. Pioneering 3D mixing models of helium layers in stars [312] and accreting white dwarfs [313] have provided some of the first possible sites for the i-process.…”

Section: How Did We Get Here?mentioning

confidence: 99%

Horizons: Nuclear Astrophysics in the 2020s and Beyond

Schatz,

Reyes,

Best

et al. 2022

Preprint

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Nuclear Astrophysics is a field at the intersection of nuclear physics and astrophysics, which seeks to understand the nuclear engines of astronomical objects and the origin of the chemical elements. This white paper summarizes progress and status of the field, the new open questions that have emerged, and the tremendous scientific opportunities that have opened up with major advances in capabilities across an ever growing number of disciplines and subfields that need to be integrated. We take a holistic view of the field discussing the unique challenges and opportunities in nuclear astrophysics in regards to science, diversity, education, and the interdisciplinarity and breadth of the field. Clearly nuclear astrophysics is a dynamic field with a bright future that is entering a new era of discovery opportunities.

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“…Approximately half of the chemical species heavier than iron are synthesized via the rapid neutron capture process, or r -process, in which seed nuclei are driven to the neutron drip line by successive capture events that occur before β-decay can take place (Burbidge et al 1957;Cameron 1982;Seeger et al 1965). Astrophysical sites which possess the extremely high neutron fluxes, mass densities, and temperatures needed to sustain rprocess nucleosynthesis include core-collapse supernovae (CCSNe; Nishimura et al 2015;Siegel et al 2019;Yong et al 2021) and compact binary mergers involving at least one neutron star (Freiburghaus et al 1999;Goriely et al 2011;Korobkin et al 2012;Surman et al 2008). It is a major goal of nuclear astrophysics to understand the relative contributions by these events to cosmic rprocess enrichment.…”

Section: Introductionmentioning

confidence: 99%

R-process Rain from Binary Neutron Star Mergers in the Galactic Halo

Amend,

Zrake,

Hartmann

2022

Preprint

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Compact binary mergers involving at least one neutron star are promising sites for the synthesis of r -process elements found in stars and planets. However, mergers are generally thought to take place at high galactic latitudes, far from any star-forming regions of the host galaxy. It is thus important to understand the physical mechanisms involved in transporting enriched material from the gas environments of the galactic halo to the star-forming disk. We investigate these processes, starting from an explosive injection event and its interaction with the halo gas medium. We show that the total outflow mass in compact binary mergers is far too low for the material to travel to the disk in a ballistic fashion. Instead, the enriched ejecta is swept into a shell, which decelerates over 1 − 10 pc scales, and becomes corrugated by the Rayleigh-Taylor instability. The corrugated shell is denser than the ambient medium, and breaks into clouds which then sink toward the disk. The sinking clouds lose thermal energy through radiative cooling, and are also ablated by shearing instabilities. We present a dynamical heuristic that models these effects, and would predict the delay times for delivery to the disk. However, we find that turbulent mass ablation is extremely efficient, and leads to the total fragmentation of sinking r -process clouds over ∼ 10 5 yr. We thus predict that enriched material from halo injection events quickly assimilates into the gas medium of the halo, and that enriched mass flow to the disk could only be accomplished by turbulent diffusion or large-scale inflowing mass currents.

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r-Process elements from magnetorotational hypernovae

Cited by 59 publications

References 56 publications

Four-hundred Very Metal-poor Stars Studied with LAMOST and Subaru. II. Elemental Abundances

Four-hundred Very Metal-poor Stars Studied with LAMOST and Subaru. II. Elemental Abundances

Horizons: Nuclear Astrophysics in the 2020s and Beyond

R-process Rain from Binary Neutron Star Mergers in the Galactic Halo

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