Figure 4 - uploaded by Friedrich -K. Thielemann
Content may be subject to copyright.
Type II supernovae are triggered by the sudden collapse of the iron core of a star of at least 8 solar masses (M 0 ), when the star's thermonuclear fuel is exhausted. The core collapses to form a proto-neutron star with a mass of about 1.4 M 0 enclosed within a radius of less than 10 kilometers. Within less than a second, a wind of neutrinos from the collapsing core is presumed to deposit enough energy in the star's outer shells to sustain the explosion triggered by a shock wave from the core collapse. The shock wave subjects the matter outside the core to explosive burning. The matter moves outward and is followed by smaller amounts of material driven by the neutrino wind. In the hottest regions just outside the core, only free nucleons remain. Farther out there are also helium nuclei (a particles ). Still farther out are somewhat heavier nuclei that presumably serve as seeds for rapid neutron capture—the r-process. (Courtesy of H. Thomas Janka.)
Source publication
Cataclysmic events in supernovae which lead to the formation of elements were investigated. Finding out whether supernovae are cataclysmic enough requires extensive astronomical observation and sophisticated computer modeling. Ongoing supernovae studies include efforts to determine the equation of state of extended nuclear matter at densities typic...
Similar publications
Photons from a gravitational wave event
Two neutron stars merging together generate a gravitational wave signal and have also been predicted to emit electromagnetic radiation. When the gravitational wave event GW170817 was detected, astronomers rushed to search for the source using conventional telescopes (see the Introduction by Smith). Coulter et...
The X-ray afterglow of short hard bursts (SHBs) of gamma rays provides compelling evidence that SHBs are produced by highly relativistic jets launched in the of birth of rotationally powered millisecond pulsars (MSPs) in merger of, or mass accretion on neutron stars in compact binaries, unlike long duration gamma ray bursts which are produced in su...
Formed in the aftermath of gravitational core-collapse supernova explosions, neutron stars are unique cosmic laboratories for probing the properties of matter under extreme conditions that cannot be reproduced in terrestrial laboratories. The interior of a neutron star, endowed with the highest magnetic fields known and with densities spanning abou...
In this work the low density regions of nuclear and neutron star matter are studied. The search for the existence of pasta phases in this region is performed within the context of the quark-meson coupling (QMC) model, which incorporates quark degrees of freedom. Fixed proton fractions are considered, as well as nuclear matter in beta equilibrium at...
Citations
... All heavy metals, from aurum (gold) to zinc including copper (Cu from Latin cuprum), are found on earth with various amounts, but they all were originally formed in the universe from helium and hydrogen via nuclear fusion inside stars during supernova explosions millions of years ago [1][2][3][4]. On our globe, copper entered the flora and became an essential micronutrient for plants, animals, and humans, who may be confronted with metabolic disorders that arise from mishandling of copper [5]. ...
Wilson disease is a genetic disorder of the liver characterized by excess accumulation of copper, which is found ubiquitously on earth and normally enters the human body in small amounts via the food chain. Many interesting disease details were published on the mechanistic steps, such as the generation of reactive oxygen species (ROS) and cuproptosis causing a copper dependent cell death. In the liver of patients with Wilson disease, also, increased iron deposits were found that may lead to iron-related ferroptosis responsible for phospholipid peroxidation within membranes of subcellular organelles. All topics are covered in this review article, in addition to the diagnostic and therapeutic issues of Wilson disease. Excess Cu2+ primarily leads to the generation of reactive oxygen species (ROS), as evidenced by early experimental studies exemplified with the detection of hydroxyl radical formation using the electron spin resonance (ESR) spin-trapping method. The generation of ROS products follows the principles of the Haber–Weiss reaction and the subsequent Fenton reaction leading to copper-related cuproptosis, and is thereby closely connected with ROS. Copper accumulation in the liver is due to impaired biliary excretion of copper caused by the inheritable malfunctioning or missing ATP7B protein. As a result, disturbed cellular homeostasis of copper prevails within the liver. Released from the liver cells due to limited storage capacity, the toxic copper enters the circulation and arrives at other organs, causing local accumulation and cell injury. This explains why copper injures not only the liver, but also the brain, kidneys, eyes, heart, muscles, and bones, explaining the multifaceted clinical features of Wilson disease. Among these are depression, psychosis, dysarthria, ataxia, writing problems, dysphagia, renal tubular dysfunction, Kayser–Fleischer corneal rings, cardiomyopathy, cardiac arrhythmias, rhabdomyolysis, osteoporosis, osteomalacia, arthritis, and arthralgia. In addition, Coombs-negative hemolytic anemia is a key feature of Wilson disease with undetectable serum haptoglobin. The modified Leipzig Scoring System helps diagnose Wilson disease. Patients with Wilson disease are well=treated first-line with copper chelators like D-penicillamine that facilitate the removal of circulating copper bound to albumin and increase in urinary copper excretion. Early chelation therapy improves prognosis. Liver transplantation is an option viewed as ultima ratio in end-stage liver disease with untreatable complications or acute liver failure. Liver transplantation finally may thus be a life-saving approach and curative treatment of the disease by replacing the hepatic gene mutation. In conclusion, Wilson disease is a multifaceted genetic disease representing a molecular and clinical challenge.
... First, subgrid SN feedback models, like the ones used in this study, can be effectively used to resolve the key evolutionary phases of NSM remnants (Montes et al. 2016). Second, our r-process injection models can be applied whether enrichment has occurred via extremely rare cc-SNe (e.g., Cowan & Thielemann 2004;Winteler et al. 2012;Nishimura et al. 2015;Mösta et al. 2018;Siegel et al. 2019) or through NSMs (e.g., Metzger et al. 2010;Roberts et al. 2011), provided that any contribution of other freshly synthesized metals (i.e., non-r-process) is less than those contained in the swept-up ISM mass by the time the blast wave reaches the cooling phase (Macias & Ramirez-Ruiz 2019). For the purposes of this study, we focus our attention on NSMs as the source of r-process elements. ...
Metal-poor stars in the Milky Way (MW) halo display large star-to-star dispersion in their r -process abundance relative to lighter elements. This suggests a chemically diverse and unmixed interstellar medium (ISM) in the early universe. This study aims to help shed light on the impact of turbulent mixing, driven by core-collapse supernovae (cc-SNe), on the r -process abundance dispersal in galactic disks. To this end, we conduct a series of simulations of small-scale galaxy patches which resolve metal-mixing mechanisms at parsec scales. Our setup includes cc-SNe feedback and enrichment from r -process sources. We find that the relative rate of the r -process events to cc-SNe is directly imprinted on the shape of the r -process distribution in the ISM with more frequent events causing more centrally peaked distributions. We consider also the fraction of metals that is lost on galactic winds and find that cc-SNe are able to efficiently launch highly enriched winds, especially in smaller galaxy models. This result suggests that smaller systems, e.g., dwarf galaxies, may require higher levels of enrichment in order to achieve similar mean r -process abundances as MW-like progenitors systems. Finally, we are able to place novel constraints on the production rate of r -process elements in the MW, 6 × 10 − 7 M ⊙ yr − 1 ≲ m ̇ rp ≪ 4.7 × 10 − 4 M ⊙ yr − 1 , imposed by accurately reproducing the mean and dispersion of [Eu/Fe] in metal-poor stars. Our results are consistent with independent estimates from alternate methods and constitute a significant reduction in the permitted parameter space.
... The exploration of rare isotopes and the reaction mechanism(s) that produce them are among the fundamental interests of modern nuclear physics [1][2][3][4]. Reaching these nuclei provides us with valuable information on r-process nucleosynthesis which is responsible for the production of a large amount of the heavier elements [5][6][7]. Apart from fragmentation [8] and spallation [9], multinucleon transfer reactions offer the means to produce these nuclei. Our group specifically focuses on the study of these reactions in the Fermi energy regime MeV/nucleon) [10][11][12][13][14][15][16][17][18]. ...
This paper presents our recent studies of multinucleon transfer in peripheral collisions in reactions below the Fermi regime. Our current focus is the study of the mass, angular and momentum distributions of the projectile-like fragments from the reaction of an 86Kr beam at 15 MeV/nucleon with a target of 64Ni. Experimental data from our previous work with the MARS spectrometer at the Cyclotron Institute of Texas A&M University were compared with model calculations. The dynamical stage of the reaction is described with either the Deep-Inelastic Transfer Model (DIT) or with the microscopic Constrained Molecular Dynamics model (CoMD). The de-excitation of the hot projectile-like fragments is performed with the GEMINI model. The momentum distributions are characterized by a quasi-elastic peak and a deep-inelastic peak. Two-body kinematics was employed to extract the total excitation energies of these regions. Through the thorough study of peripheral reactions in the Fermi energy regime we expect to gain valuable information that could lead to the understanding of how the rare isotopes in regions such as the r-process path and the neutron drip line are formed and the reaction mechanism(s) that take place.
... First, sub-grid SN feedback models, like the ones used in this study, can be effectively used to resolve the key evolutionary phases of NSM remnants (Montes et al. 2016). Second, our r-process injection models can be applied whether enrichment has occurred via extremely rare cc-SNe (e.g., Cowan & Thielemann 2004;Winteler et al. 2012;Nishimura et al. 2015;Mösta et al. 2018;Siegel et al. 2019), or through NSMs (e.g., Metzger et al. 2010;Roberts et al. 2011), provided that any contribution of other freshlysynthesized metals (i.e., non r-process) is less than those contained in the swept-up ISM mass by the time the blast wave reaches the cooling phase (Macias & Ramirez-Ruiz 2019). ...
Metal-poor stars in the Milky Way (MW) halo display large star-to-star dispersion in their r-process abundance relative to lighter elements. This suggests a chemically diverse and unmixed interstellar medium (ISM) in the early Universe. This study aims to help shed light on the impact of turbulent mixing, driven by core collapse supernovae (cc-SNe), on the r-process abundance dispersal in galactic disks. To this end, we conduct a series of simulations of small-scale galaxy patches which resolve metal mixing mechanisms at parsec scales. Our set-up includes cc-SNe feedback and enrichment from r-process sources. We find that the relative rate of the r-process events to cc-SNe is directly imprinted on the shape of the r-process distribution in the ISM with more frequent events causing more centrally peaked distributions. We consider also the fraction of metals that is lost on galactic winds and find that cc-SNe are able to efficiently launch highly enriched winds, especially in smaller galaxy models. This result suggests that smaller systems, e.g. dwarf galaxies, may require higher levels of enrichment in order to achieve similar mean r-process abundances as MW-like progenitors systems. Finally, we are able to place novel constraints on the production rate of r-process elements in the MW, $6 \times 10^{-7} {M_\odot / \rm yr} \lesssim \dot{m}_{\rm rp} \ll 4.7 \times 10^{-4} {M_\odot / \rm yr} $, imposed by accurately reproducing the mean and dispersion of [Eu/Fe] in metal-poor stars. Our results are consistent with independent estimates from alternate methods and constitute a significant reduction in the permitted parameter space.
... The two stable isotopes of Eu, 151 and 153, are produced exclusively through r-process enrichment (Prantzos et al. 2020;Cowan & Thielemann 2004). As such, paired with Ba, Eu is often used as a discriminating indicator on whether heavy elements in a star originate predominantly from s-or r-process enrichment (e.g., Aguado et al. 2021). ...
One-zone Galactic Chemical Evolution (GCE) models have provided useful insights on a great wealth of average abundance patterns in many environments, especially for the Milky Way and its satellites. However, the scatter of such abundance patterns is still a challenging aspect to reproduce. The leading hypothesis is that dynamics is a likely major source of the dispersion. In this work we test another hypothesis, namely that different assumptions on yield modeling may be at play simultaneously. We compare whether the abundance patterns spanned by the models are consistent with those observed in Galactic data. First, we test the performance of recent yield tabulations, and we show which of these tabulations best fit Galactic stellar abundances. We then group the models and test if yield combinations match data scatter and standard deviation. On a fixed Milky-Way-like parametrization of NuPyCEE, we test a selection of yields for the three dominant yield sets: low-to-intermediate mass stars, massive stars, and Type Ia supernovae. We also include the production of r-process elements by neutron star mergers. We explore the statistical properties spanned by such yields. We identify the differences and commonalities among yield sets. We define criteria that estimate whether an element is in agreement with the data, or if the model overestimates or underestimates it in various redshift bins. While it is true that yields are a major source of uncertainty in GCE models, the scatter of abundances in stellar spectra cannot be explained by a simple averaging of runs across yield prescriptions.
... The area of β-unstable nuclei which are still stable against neutron or proton emission, as predicted by nuclear mass models, appear in a light green shade. Horizontal or vertical lines stand for neutron or proton shell closures, N = 8, 20, 28, 50, 82, 126, 184 and Z = 8, 20, 26, 28, 50, 82 (, 114), the one in brackets not shown here [14]: solar s-process abundances (blue), resulting from a superposition of stellar s-process sources [6]. The subtraction from global solar abundances provides the abundance contributions due to the remaining processes which create heavy nuclei up to the actinides, mainly the before-mentioned and later discussed r-process (red) kinks. ...
This contribution starts with memories about Franz Käppeler, as a human being and a scientist, his impact on neutron capture nucleosynthesis via experiments and astrophysical studies, before extending from his focus (the s-process) to the r-process, discussing its mechanism, related astrophysical sites and examining in a concluding section its role during galactic evolution.
... Observations established that the [Eu/Fe] ratios differ by several orders of magnitude for very old stars, the deviations becoming smaller for younger stars (as metallicity grows) [11]. Since europium is formed in the r-process exclusively, it is an indicator of the degree of enrichment of chemical elements in isotopes formed in the r-process. ...
... The calculation assumes that the r-process path passes through 128 Pd and 127 Rh, which act as classical waiting points with their abundances weighted by their respective half-lives, and that the decay to stability follows an instantaneous freeze-out. These isotones lying on the N = 82 shell closure are part of the r-process path in many calculations [43,44]. The resulting isobaric abundance distribution of the stable nuclei produced after the progenitor 128 Pd and 127 Rh abundances decay back to stability is shown in Figure 4. Abundance uncertainties were calculated using a Monte Carlo approach where the experimental P 1n values were varied within their uncertainties. ...
Theoretical models of β-delayed neutron emission are used as crucial inputs in r-process calculations. Benchmarking the predictions of these models is a challenge due to a lack of currently available experimental data. In this work the β-delayed neutron emission probabilities of 33 nuclides in the important mass regions south and south-west of ¹³²Sn are presented, 16 for the first time. The measurements were performed at RIKEN using the Advanced Implantation Detector Array (AIDA) and the BRIKEN neutron detector array. The P1n values presented constrain the predictions of theoretical models in the region, affecting the final abundance distribution of the second r-process peak at A≈130.
... On the fundamental nuclear physics side, neutron-rich isotopes could provide key information to test nuclear models and to understand the nuclear interaction [1][2][3][4][5][6][7]. On the astrophysics side, the slow (s-process) and the rapid (r-process) neutron capture processes of neutron capture nucleosynthesis contribute in roughly equal amounts to the total elemental abundances beyond iron [9][10][11][12][13]. Although the neutron capture nucleosynthesis has been studied extensively, some issues still remain open, such as the s-process branching [9,14] and the astrophysical sites of the r-process [10,[14][15][16][17][18][19][20][21][22][23][24][25][26]. ...
... where the prefactor accounts for the radioactive decay, and the term MN(s − 1) gives the one-pulse result for the initial conditions N(s − 1) (with the subscript i on a vector, we denote the ith component of the corresponding vector). With Eq. (12), the populations can be computed recursively. ...
... (12), we assume τ i = ∞ and γ k = 1 (i.e., thin target assumption). Then Eq. (12) becomes ...
The production of neutron-rich isotopes and the occurrence of neutron capture cascades via laser-driven (pulsed) neutron sources are investigated theoretically. The considered scenario involves the interaction of a laser-driven neutron beam with a target made of a single type of seed nuclide. We present a comprehensive study over 95 seed nuclides in the range 3≤Z≤100 from Li37 to Fm100255. For each element, the heaviest sufficiently long-lived (half-life >1 h) isotope whose data is available in the recent ENDF-B-VIII.0 neutron sublibrary is considered. We identify interesting seed nuclides with good performance in the production of neutron-rich isotopes where neutron capture cascades may occur. The effects of the neutron number per pulse, the neutron-target interaction size, and the number of neutron pulses are also analyzed. Our results show the possibility of observing up to four successive neutron capture events, leading to neutron-rich isotopes with four more neutrons than the original seed nuclide. This hints at experimental possibilities to produce neutron-rich isotopes and simulate neutron capture nucleosynthesis in the laboratory. With several selected interesting seed nuclides in the region of the branching point of the s-process (Sb51126, Lu71176, and Re75187) or the waiting point of the r-process (Lu, Re, Os, Tm, Ir, and Au), we expect that laser-driven experiments can shed light on our understanding of nucleosynthesis.
... The abundance distribution of any stable nuclide depends strongly on the calculated beta decay half-lives of its neutron-rich progenitors. For the abundance distribution of elements in the solar system, the Figure 1.1: Solar system abundances of heavy elements produced by r-and s-process, adopted from [8]. ...
The fully microscopic approach based on pn-QRPA is employed for the calculation of b-decay properties
of closed-neutron magic shell waiting point (WP) nuclei composed of N=50 and 82. These
calculations are key ingredients for the simulation of core-collapse supernova dynamics and for better
comprehension of the r-process. These calculations bears astrophysical importance vis-à-vis boosting
of the r-process. The b-decay properties are calculated under both stellar and terrestrial conditions
by incorporating Gamow-Teller (allowed GT) and Unique First Forbidden (U1F) transitions. The
computed b-decay properties comprise of the energy rates of b-delayed neutron, their emission probabilities
(Pn), stellar weak rates (l), and total half-lives as a sum of both allowed GT and U1F part for
selected waiting point nuclei of astrophysical importance. The outcomes are compared with previous
computations and experimental data. These outcomes are in best concurrence with experimental
data. For specific selected cases, it is observed that the total half-lives are considerably decreased
with the inclusion of U1F transitions. These computations are not in concurrence with the shell
model investigation where it is expressed that forbidden contribution decreased the total half-lives
for closed-neutron waiting-point nuclei composed of N=126. The theoretical Ikeda Sum Rule (ISR)
validity is also checked for selected cases. For even-even selected cases the theoretical ISR is fully
satisfied with the pn-QRPA calculated ISR. Amongst the selected odd-A waiting point nuclei, the rule
is only violated (0:7%) in 81Ga case.
