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We report on the PUSH method for artificially triggering core-collapse supernova explosions of massive stars in spherical symmetry. The PUSH method increases the energy deposition in the gain region proportionally to the heavy flavor neutrino fluxes.We summarize the parameter dependence of the method and calibrate PUSH to reproduce SN 1987A observables. We identify a best-fit progenitor and set of parameters that fit the explosion properties of SN 1987A, assuming 0.1 M⊙ of fallback. For the explored progenitor range of 18-21 M⊙, we find correlations between explosion properties and the compactness of the progenitor model.

Based on a new mechanism to drive spherically symmetric core-collapse supernovae, PUSH, we perform full network nucleosynthesis calculations for different progenitors. While the ⁵⁶⁻⁵⁸Ni yields match the observational data very well for certain progenitors, the ejected titanium masses in our calculations are lower than the values inferred from observations. We demonstrate the dependence of ejecta composition on the progenitor structure and the mass cut. Furthermore, we discuss possible solutions to the well-known problem of titanium underproduction.

We present the state-of-the-art single-zone nuclear reaction network WinNet that is capable of calculating the nucleosynthetic yields of a large variety of astrophysical environments and conditions. This ranges from the calculation of the primordial nucleosynthesis, where only a few nuclei are considered, to the ejecta of neutron star mergers with several thousands of involved nuclei. Here we describe the underlying physics and implementation details of the reaction network. We additionally present the numerical implementation of two different integration methods, the implicit Euler method and Gears method along with their advantages and disadvantages. We furthermore describe basic example cases of thermodynamic conditions that we provide together with the network and demonstrate the reliability of the code by using simple test cases. With this publication, WinNet is publicly available and open source at GitHub and Zenodo.

As hydro-meteorological hazards are predicted to become more frequent and intense in the future, scholars and policymakers are increasingly concerned about their security implications, especially in the context of ongoing climate change. Our study contributes to this debate by analysing the pathways to water-related conflict onset under drought conditions in the Middle East and North Africa (MENA) region between 1996 and 2009. It is also the first such analysis that focuses on small-scale conflicts involving little or no physical violence, such as protests or demonstrations. These nonviolent conflicts are politically relevant, yet understudied in the literature on climate change and conflict, environmental security, and political instability. We employ the method of qualitative comparative analysis (QCA) to integrate quantitative and qualitative data at various scales (national, regional, local) for a sample of 34 cases (17 of which experienced conflict onset). Our findings show that pre-existing cleavages and either autocratic political systems or cuts of the public water supply are relevant predictors of nonviolent, water-related conflict onset during droughts. Grievances deeply embedded into socio-economic structures in combination with a triggering event like a drought or water cuts are hence driving such water-related conflicts, especially in the absence of proper political institutions. We thus argue that drought–conflict links are highly context-dependent even for nonviolent, local conflicts, hence challenging determinist narratives that claim direct interlinkages between climate change, hydro-meteorological disasters and conflict.

An interdisciplinary group of scientists working on human-environment interactions discussed the state of knowledge on the economic, political, and social implications of environmental crises and identified pathways for future research.

Misleading claims about mass migration induced by climate change continue to surface in both academia and policy. This requires a new research agenda on ‘climate mobilities’ that moves beyond simplistic assumptions and more accurately advances knowledge of the nexus between human mobility and climate change.

The $\nu p$ process appears in proton-rich, hot matter which is expanding in a neutrino wind and may be realised in explosive environments such as core-collapse supernovae or in outflows from accretion disks. The impact of uncertainties in nuclear reaction cross sections on the finally produced abundances has been studied by applying Monte Carlo variation of all astrophysical reaction rates in a large reaction network. As the detailed astrophysical conditions of the $\nu p$ process still are unknown, a parameter study was performed, with 23 trajectories covering a large range of entropies and $Y_\mathrm{e}$. The resulting abundance uncertainties are given for each trajectory. The $\nu p$ process has been speculated to contribute to the light $p$ nuclides but it was not possible so far to reproduce the solar isotope ratios. It is found that it is possible to reproduce the solar $^{92}$Mo/$^{94}$Mo abundance ratio within nuclear uncertainties, even within a single trajectory. The solar values of the abundances in the Kr-Sr region relative to the Mo region, however, cannot be achieved within a single trajectory. They may still be obtained from a weighted superposition of different trajectories, though, depending on the actual conditions in the production site. For a stronger constraint of the required conditions, it would be necessary to reduce the uncertainties in the 3$\alpha$ and $^{56}$Ni(n,p)$^{56}$Co rates at temperatures $T>3$ GK., Comment: 6 pages, 1 figure, 2 tables; to appear in JPS Conference Proceedings (OMEG15, 2019); summarizes and expands on arXiv:1907.13129 with an additional discussion of isotopic ratios of p-nuclides; v2: typos fixed

It has been suggested that a $\nu$p process can occur when hot, dense, and proton-rich matter is expanding within a strong flux of anti-neutrinos. In such an environment, proton-rich nuclides can be produced in sequences of proton captures and (n,p) reactions, where the free neutrons are created in situ by $\overline{\nu}_\mathrm{e}+\mathrm{p} \rightarrow \mathrm{n}+\mathrm{e}^+$ reactions. The detailed hydrodynamic evolution determines where the nucleosynthesis path turns off from N = Z line and how far up the nuclear chart it runs. In this work, the uncertainties on the final isotopic abundances stemming from uncertainties in the nuclear reaction rates were investigated in a large-scale Monte Carlo approach, simultaneously varying ten thousand reactions. A large range of model conditions was investigated because a definitive astrophysical site for the $\nu$p process has not yet been identified. The present parameter study provides, for each model, identification of the key nuclear reactions dominating the uncertainty for a given nuclide abundance. As all rates appearing in the $\nu$p process involve unstable nuclei, and thus only theoretical rates are available, the final abundance uncertainties are larger than those for nucleosynthesis processes closer to stability. Nevertheless, most uncertainties remain below a factor of three in trajectories with robust nucleosynthesis. More extreme conditions allow production of heavier nuclides but show larger uncertainties because of the accumulation of the uncertainties in many rates and because the termination of nucleosynthesis is not at equilibrium conditions. It is also found that the solar ratio of the abundances of ${}^{92}$Mo and ${}^{94}$Mo could be reproduced within uncertainties., Comment: 19 pages, 12 figures, 8 tables, accepted for publication in MNRAS