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Carbon-enhanced metal-poor (CEMP) stars in the Galactic halo have a wide range of neutron-capture element abundance patterns. To identify their origin, we investigate three modes of s -process nucleosynthesis that have been proposed to operate in extremely metal-poor asymptotic giant branch (AGB) stars: convective 13C burning, which occurs when hydrogen is engulfed by helium-flash convection in low-mass AGB stars; convective 22Ne burning, which occurs in helium-flash convection of intermediate-mass AGB stars; and radiative 13C burning, which occurs in the 13C pocket that is formed during inter-pulse periods. We show that the production of s -process elements per iron seed (s -process efficiency) does not depend on metallicity below [Fe |$/$| H] = −2, because 16O in the helium zone dominates the neutron poison. The convective 13C mode can produce a variety of s -process efficiencies for Sr, Ba, and Pb, including the maxima observed among CEMP stars. The 22Ne mode only produces the lowest end of s -process efficiencies among CEMP models. We show that the combination of these two modes can explain the full range of observed enrichment of s -process elements in CEMP stars. In contrast, the 13C pocket mode can hardly explain the high level of enrichment observed in some CEMP stars, even if considering star-to-star variations of the mass of the 13C pocket. These results provide a basis for discussing the binary mass transfer origin of CEMP stars and their subgroups. [ABSTRACT FROM AUTHOR]

Martian global dust storms (GDS) can significantly affect the water cycle in the lower atmosphere (0−40 km). We compare the evolution of water vapor abundances, dust opacity and surface temperatures in the Southern Polar Region (SPR) during GDS years of MY25, MY28, and MY34 relative to years without GDS. During all GDS years, the vapor abundances decrease in the lower atmosphere in the SPR following the storm. Our results suggest that this decrease could be the result of disruption of the southward transport of vapor by atmospheric circulation. Alternatively, the decrease in vapor abundances could be caused by decreased desorption of vapor from the subsurface. Plain Language Summary: This work presents comprehensive analysis of how water vapor in the Martian polar atmosphere reacts to large dust storms in different years. Measurements of water vapor, atmospheric dust, and surface temperatures collected by different spacecraft instruments in years with and without large dust storms are compared. These comparisons inform our understanding of how Martian water vapor is transported through the atmosphere and how it interacts with the surface. Large dust storms decrease the amount of water vapor in the southern polar region. This may indicate that the transport of vapor to the pole is reduced by the storms, or that dusty atmosphere cools the surface and reduces the amount of vapor released from the subsurface. Key Points: Water vapor abundances over the Southern Polar Region of Mars are reduced following a global dust storm (GDS)The decrease in water vapor abundances could be caused by disruption of southward vapor transport by a GDSAlternatively, the decrease could be caused by changes in the surface‐atmosphere vapor exchange [ABSTRACT FROM AUTHOR]

Microplastic (MP) contamination has grown to be a serious environmental issue in recent years. Microplastics are plastic particles, with a size of less than 5 mm, that are either produced specifically for use in a variety of products or emerge through the decomposition of larger plastic items. Data from prior research conducted in wastewater treatment plants (WWTPs) regarding the abundances of microplastics across different treatment stages of WWTPs in different countries were compiled using online scientific databases. This research found that although Turkey only managed to attain a removal rate of 48.0%, Iran and the United States were able to reach removal rates of over 90.0%. It was discovered that two plants in Morocco had relatively high removal efficiencies, with one achieving a remarkable 74.0% removal rate and the other an 87.0% removal rate. The predominance of fibers and fragments in the influent and effluent across all studied locations shows the difficulty in effectively removing them from wastewater. The widespread abundance of microplastic polymers from diverse sources poses a significant challenge for wastewater treatment facilities in efficiently managing and eliminating these pollutants. This research further demonstrated regional differences in the color composition of microplastics, with black, transparent, blue, and red being prominent colors in the influent and effluent of some regions. These color variations can influence the detection and identification processes, which are crucial for developing targeted removal strategies. In conclusion, it is essential to address the pervasiveness of microplastics in wastewater treatment plants. Improving treatment procedures, protecting the ecosystem, and conserving water quality for a sustainable future all depend on addressing the various sources of these contaminants.

De-excitation gamma-ray lines, produced by nuclei colliding with protons, provide information about astrophysical environments where particles have kinetic energies of 10–100 MeV per nucleon. In general, such environments can be categorized into two types: the interaction between non-thermal MeV cosmic rays and ambient gas, and the other is thermal plasma with a temperature above a few MeV. In this paper, we focus on the latter type and investigate the production of de-excitation gamma-ray lines in very hot thermal plasma, especially the dependence of the line profile on the plasma temperature. We have calculated the line profile of prompt gamma rays from 12C and 16O and found that when nuclei have a higher temperature than protons, gamma-ray line profiles can have a complex shape unique to each nucleus species. This is caused by anisotropic gamma-ray emission in the nucleus rest frame. We propose that the spectroscopy of nuclear de-excitation gamma-ray lines may enable to probe energy distribution in very hot astrophysical plasmas. This diagnostics can be a new and powerful technique to investigate the physical state of a two-temperature accretion flows onto a black hole, especially the energy distributions of the protons and nuclei, which are difficult to access for any other diagnostics. [ABSTRACT FROM AUTHOR]

Magnetized hypermassive neutron stars (HMNSs) have been proposed as a way for neutron star mergers to produce high electron fraction, high-velocity ejecta, as required by kilonova models to explain the observed light curve of GW170817. The HMNS drives outflows through neutrino energy deposition and mechanical oscillations, and raises the electron fraction of outflows through neutrino interactions before collapsing to a black hole (BH). Here, we perform 3D numerical simulations of HMNS–torus systems in ideal magnetohydrodynamics, using a leakage/absorption scheme for neutrino transport, the nuclear APR equation of state, and Newtonian self-gravity, with a pseudo-Newtonian potential added after BH formation. Due to the uncertainty in the HMNS collapse time, we choose two different parametrized times to induce collapse. We also explore two initial magnetic field geometries in the torus, and evolve the systems until the outflows diminish significantly (⁠|$\sim\!\! 1\!\! - \!\!2\ \mathrm{s}$|⁠). We find bluer, faster outflows as compared to equivalent BH–torus systems, producing M ∼ 10−3 M⊙ of ejecta with Y e ≥ 0.25 and v ≥ 0.25 c by the simulation end. Approximately half the outflows are launched in disc winds at times |$t\lesssim 500 \ \mathrm{ms}$|⁠ , with a broad distribution of electron fractions and velocities, depending on the initial condition. The remaining outflows are thermally driven, characterized by lower velocities and electron fractions. Nucleosynthesis with tracer particles shows patterns resembling solar abundances in all models. Although outflows from our simulations do not match those inferred from two-component modelling of the GW170817 kilonova, self-consistent multidimensional detailed kilonova models are required to determine whether our outflows can power the blue kilonova. [ABSTRACT FROM AUTHOR]

The most massive stars provide an essential source of recycled material for young clusters and galaxies. While very massive stars (VMSs, M>100  |$\rm {\rm M}_{\odot }$|⁠) are relatively rare compared to O stars, they lose disproportionately large amounts of mass already from the onset of core H-burning. VMS have optically thick winds with elevated mass-loss rates in comparison to optically thin standard O-star winds. We compute wind yields and ejected masses on the main sequence, and we compare enhanced mass-loss rates to standard ones. We calculate solar metallicity wind yields from MESA stellar evolution models in the range 50–500  |$\rm {\rm M}_{\odot }$|⁠ , including a large nuclear network of 92 isotopes, investigating not only the CNO-cycle, but also the Ne–Na and Mg–Al cycles. VMS with enhanced winds eject 5–10 times more H-processed elements (N, Ne, Na, Al) on the main sequence in comparison to standard winds, with possible consequences for observed anticorrelations, such as C–N and Na–O, in globular clusters. We find that for VMS 95 per cent of the total wind yields is produced on the main sequence, while only ∼ 5 per cent is supplied by the post-main sequence. This implies that VMS with enhanced winds are the primary source of 26Al, contrasting previous works where classical Wolf–Rayet winds had been suggested to be responsible for galactic 26Al enrichment. Finally, 200  |$\rm {\rm M}_{\odot }$| stars eject 100 times more of each heavy element in their winds than 50  |$\rm {\rm M}_{\odot }$| stars, and even when weighted by an IMF their wind contribution is still an order of magnitude higher than that of 50  |$\rm {\rm M}_{\odot }$| stars. [ABSTRACT FROM AUTHOR]

Core-collapse explosions of massive stars leave behind neutron stars, with a known diversity that includes the 'Central Compact Objects' (CCOs). Typified by the neutron star discovered near the centre of the Cas A supernova remnant (SNR), CCOs have been observed to shine only in X-rays. To address their supernova progenitors, we perform a systematic study of SNRs that contain a CCO and display X-ray emission from their shock-heated ejecta. We make use of X-ray data primarily using the Chandra X-ray observatory, complemented with XMM–Newton. This study uses a systematic approach to the analysis of each SNR aimed at addressing the supernova progenitor as well as the explosion properties (energy and ambient density). After fitting for the ejecta abundances estimated from a spatially resolved spectroscopic study, we compare the data to six nucleosynthesis models making predictions on supernova ejecta yields in core-collapse explosions. We find that the explosion models commonly used by the astrophysics community do not match the ejecta yields for any of the SNRs, suggesting additional physics, for example multidimensional explosion models or updated progenitor structures, are required. Overall we find low-mass (≤25 solar masses) progenitors among the massive stars population and low-energy explosions (<1051 ergs). We discuss degeneracies in our model fitting, particularly how altering the explosion energy affects the estimate of the progenitor mass. Our systematic study highlights the need for improving on the theoretical models for nucleosynthesis predictions as well as for sensitive, high-resolution spectroscopy observations to be acquired with next generation X-ray missions. [ABSTRACT FROM AUTHOR]

The abundances of about half of the elements heavier than iron are subtly attuned by the rapid neutron capture process or r -process, which is intimately related to the competition between neutron capture, photo-disintegration, and β-decay rates, and ultimately depends on the binding energy of neutron-rich nuclei. The well-known Bethe–Weizsäcker semi-empirical mass formula describes the binding energy of ground states – i.e. nuclei with temperatures of T  = 0 MeV – with the symmetry energy parameter converging between 23 and 27 MeV for heavy nuclei. We find an unexpected enhancement of the symmetry energy well above the ground state – at higher temperatures of T ≈ 0.7–1.0 MeV – from the available data of giant dipole resonances built on excited states. Although these are likely the temperatures where seed nuclei are created – during the cooling down of the ejecta following neutron-star mergers or collapsars – the fact that the symmetry energy remains constant between T ≈ 0.7 and 1.0 MeV, may suggest an enhanced symmetry energy at lower temperatures, where neutron-capture may start occurring. Calculations using this relatively larger symmetry energy yield a reduction of the binding energy per nucleon for heavy neutron-rich nuclei and inhibits radiative neutron-capture rates. This results in a substantial close in of the neutron drip line which may elucidate the long sought universality of heavy-element abundances through the r -process; as inferred from the similar abundances found in extremely metal-poor stars and the Sun. Sensitivity studies of r -process network calculations have been performed using more sophisticated mass models. [ABSTRACT FROM AUTHOR]

Local geological and tectonic processes have been pivotal in shaping the diverse sedimentation patterns observed in Jordan, forming sub-basins characterized by elevated organic matter content (TOC). This study aims to characterize the Maastrichtian basin, focusing on sedimentation rates using calcareous nannofossils and understanding paleoecological and paleo-oceanic conditions. It offers insights into the paleoenvironmental factors impacting oil shale deposition in the late Maastrichtian–Paleocene period. It employs classical biostratigraphical, semi-quantitative, and statistical methodologies to achieve its objectives of age determination and paleoecological insights. A total of 116 smear slides from two sites were obtained: the first, consisting of WA-1 (23 samples), WA-2 (18 samples), and WA-3 (11 samples), and the second, with 60 samples. Notably, the sites exhibit varying topography. WA-1 and WA-2, situated at lower elevations, have the highest Total Organic Carbon (TOC) levels, while areas with higher elevations in section four are visually identified by a light color. The study revealed varying patterns of calcareous nannofossil richness in the two investigated sites. These patterns were instrumental in defining biozones, with the utilization of marker species such as Lithraphidites quadratus, Micula murus, Micula prinsii, and Cruciplacolithus tenuis. Chronologically, these sections were classified as Maastrichtian–Paleogene, encompassing the following biozones in sequential order: UC-20a, UC-20b, UC-20c, UC-20d, and NP-2. Furthermore, the study identified two hiatus intervals, observed in sections WA-1 and KAS-1. The absence of certain biozones in the analyzed sections suggests that these sections correspond to distinct geological blocks within the basin, underscoring the role of tectonic forces during the deposition period. The sedimentation rate initially commenced at low levels but gradually increased due to topographic alterations. Notably, the biozone UC-20c demonstrated a clear trend toward warming and enhanced nutrient availability. In this context, the abundance and diversity of species were associated with increased continental influx into the sub-basin, resulting in rising nutrient levels and the number of calcareous nannofossils. This study enhances the understanding of the local and global effects such as tectonic and climates of the continuity of basins by deciphering calcareous nannofossil patterns and their correlation with sedimentation factors. [ABSTRACT FROM AUTHOR]

We perform a comparative analysis of nucleosynthesis yields from binary neutron star (BNS) mergers, black hole-neutron star (BHNS) mergers, and core-collapse supernovae (CCSNe) with the goal of determining which are the most dominant sources of r-process enrichment observed in stars. We find that BNS and BHNS binaries may eject similar mass distributions of robust r-process nuclei post-merger (up to third peak and actinides, A ∼ 200−240), after accounting for the volumetric event rates. Magnetorotational (MR) CCSNe likely undergo a weak r-process (up to A ∼ 140) and contribute to the production of light element primary process (LEPP) nuclei, whereas typical thermal, neutrino-driven CCSNe only synthesize up to first r-process peak nuclei (A ∼ 80−90). We also find that the upper limit to the rate of MR CCSNe is |$\lesssim 1~{{\ \rm per\ cent}}$| the rate of typical thermal CCSNe; if the rate was higher, then weak r-process nuclei would be overproduced. Although the largest uncertainty is from the volumetric event rate, the prospects are encouraging for confirming these rates in the next few years with upcoming surveys. Using a simple model to estimate the resulting kilonova light curve from mergers and our set of fiducial merger parameters, we predict that ∼7 BNS and ∼2 BHNS events will be detectable per year by the Vera C. Rubin Observatory (LSST), with prior gravitational wave (GW) triggers. [ABSTRACT FROM AUTHOR]

In the environments where the abundance of heavy elements is low, rare events are expected to impact the chemical enrichment. Dwarf galaxies have small masses, low average metallicities and in general low star formation rates, and thus investigating the chemical enrichment provides understanding on the impact of each source of elements on the chemical abundance. Using a chemical evolution model in which the rarity is introduced, we investigate the impact of rare events on the chemical enrichment for Local Group dwarf galaxies. In the model, the occurrence of individual sources of elements is estimated with the star formation history derived by the colour–magnitude diagram. The abundance ratios of trans-iron elements to iron predicted by the model show the oscillation at the lowest metallicities because of the r -process events. In the case of a galaxy of a lower mass, the oscillation caused by neutron star mergers is also seen at higher metallicities, which suggests that the rarity can be important in lower-mass systems. Regarding the source of the chemical enrichment, we observe that the r -process sites seem to contribute more to the production of trans-iron elements at low metallicities, but massive stars of different rotating velocities also contribute to create part of the dispersion of the abundance ratios through the s -process. Both observational and theoretical data, including nucleosynthesis calculations and the chemical abundance of metal-poor stars, are needed to obtain deeper insights into the sources of the chemical enrichment at low metallicities. [ABSTRACT FROM AUTHOR]

Context. Accurate 42Ti(p,γ)43V reaction rates are crucial for understanding the nucleosynthesis path of the rapid capture process (rp process) that occurs in X-ray bursts. Aims. We aim to improve the thermonuclear rates of 42Ti(p,γ)43V based on more complete resonance information and a more accurate direct component, together with the recently released nuclear masses data. We also explore the impact of the newly obtained rates on the rp process. Methods. We reevaluated the reaction rate of 42Ti(p,γ)43V by the sum of the isolated resonance contribution instead of the Hauser-Feshbach statistical model. We used a Monte Carlo method to derive the associated uncertainties of new rates. The nucleosynthesis simulations were performed via the NuGrid post-processing code ppn. Results. The new rates differ from previous estimations due to the use of a series of updated resonance parameters and a direct S factor. Compared with the previous results from the Hauser-Feshbach statistical model, which assumes compound nucleus 43V with a sufficiently high-level density in the energy region of astrophysical interest, large differences exist over the entire temperature region of rp-process interest, up to two orders of magnitude. We consistently calculated the photodisintegration rate using our new nuclear masses via the detailed balance principle, and found the discrepancies among the different reverse rates are much larger than those for the forward rate, up to ten orders of magnitude at the temperature of 108 K. Using a trajectory with a peak temperature of 1.95×109 K, we performed the rp-process nucleosynthesis simulations to investigate the impact of the new rates. Our calculations show that the adoption of the new forward and reverse rates result in abundance variations for Sc and Ca of 128% and 49%, respectively, compared to the variations for the statistical model rates. On the other hand, the overall abundance pattern is not significantly affected. The results of using new rates also confirm that the rp-process path does not bypass the isotope 43V. Conclusions. Our study found that the Hauser-Feshbach statistical model is inappropriate to the reaction rate evaluation for 42Ti(p,γ)43V. The adoption of the new rates confirms that the reaction path of 42Ti(p,γ)43V(p,γ)44Cr(β+)44V is a key branch of the rp process in X-ray bursts. [ABSTRACT FROM AUTHOR]

Context. The γ-process nucleosynthesis in core-collapse supernovae is generally accepted as a feasible process for the synthesis of neutron-deficient isotopes beyond iron. However, crucial discrepancies between theory and observations still exist: the average yields of γ-process nucleosynthesis from massive stars are still insufficient to reproduce the solar distribution in galactic chemical evolution calculations, and the yields of the Mo and Ru isotopes are a factor of ten lower than the yields of the other γ-process nuclei. Aims. We investigate the γ-process in five sets of core-collapse supernova models published in the literature with initial masses of 15, 20, and 25 M⊙ at solar metallicity. Methods. We compared the γ-process overproduction factors from the different models. To highlight the possible effect of nuclear physics input, we also considered 23 ratios of two isotopes close to each other in mass relative to their solar values. Further, we investigated the contribution of C–O shell mergers in the supernova progenitors as an additional site of the γ-process. Results. Our analysis shows that a large scatter among the different models exists for both the γ-process integrated yields and the isotopic ratios. We find only ten ratios that agree with their solar values, all the others differ by at least a factor of three from the solar values in all the considered sets of models. The γ-process within C–O shell mergers mostly influences the isotopic ratios that involve intermediate and heavy proton-rich isotopes with A > 100. Conclusions. We conclude that there are large discrepancies both among the different data sets and between the model predictions and the solar abundance distribution. More calculations are needed; particularly updating the nuclear network, because the majority of the models considered in this work do not use the latest reaction rates for the γ-process nucleosynthesis. Moreover, the role of C–O shell mergers requires further investigation. [ABSTRACT FROM AUTHOR]

Aims. We constrain the role of different Type Ia supernova (SN Ia) channels in the chemical enrichment of the Galaxy by studying the abundances of nickel in Galactic stars. We investigated four different SN Ia sub-classes, including the classical single-degenerate near-Chandrasekhar mass (Mch) SN Ia, the fainter SN Iax systems associated with He accretion from the companion, as well as two sub-Chandrasekhar mass (sub-Mch) SN Ia channels. The latter include the double detonation of a white dwarf accreting helium-rich matter and violent white dwarf mergers. Methods. The chemical abundances in Galactic stars were determined using Gaia eDR3 astrometry and photometry and high-resolution optical spectra. Non-local thermodynamic equilibrium (NLTE) models of Fe and Ni were used in the abundance analysis. We included new delay-time distributions arising from the different SN Ia channels in models of the Galactic chemical evolution, as well as recent yields for core-collapse supernovae and asymptotic giant branch stars. The data-model comparison was performed using a Markov chain Monte Carlo framework that allowed us to explore the entire parameter space allowed by the diversity of explosion mechanisms and the Galactic SN Ia rate, taking the uncertainties of the observed data into account. Results. We show that NLTE effects have a non-negligible impact on the observed [Ni/Fe] ratios in the Galactic stars. The NLTE corrections to Ni abundances are not large, but strictly positive, lifting the [Ni/Fe] ratios by ∼ + 0.15 dex at [Fe/H] −2. We find that the distributions of [Ni/Fe] in LTE and in NLTE are very tight, with a scatter of ≲0.1 dex at all metallicities. This supports earlier work. In LTE, most stars have scaled solar Ni abundances, [Ni/Fe] ≈ 0, with a slight tendency for sub-solar [Ni/Fe] ratios at lower [Fe/H]. In NLTE, however, we find a mild anti-correlation between [Ni/Fe] and metallicity, and slightly elevated [Ni/Fe] ratios at [Fe/H] ≲ −1.0. The NLTE data can be explained by models of the Galactic chemical evolution that are calculated with a substantial fraction, ∼75%, of sub-Mch SN Ia. [ABSTRACT FROM AUTHOR]

We investigate the origin of neutron-capture elements by analysing their abundance patterns and radial gradients in the Galactic thin disc. We adopt a detailed two-infall chemical evolution model for the Milky Way, including state-of-the-art nucleosynthesis prescriptions for neutron-capture elements. We consider r-process nucleosynthesis from merging neutron stars (MNS) and magneto-rotational supernovae (MR-SNe), and s-process synthesis from low- and intermediate-mass stars (LIMS) and rotating massive stars. The predictions of our model are compared with data from the sixth data release of the Gaia -ESO survey, from which we consider 62 open clusters with age ≳ 0.1 Gyr and ∼1300 Milky Way disc field stars. We conclude that: (i) the [Eu/Fe] versus [Fe/H] diagram is reproduced by both prompt and delayed sources, with the prompt source dominating Eu production; (ii) rotation in massive stars significantly contributes to the first peak s-process elements, but MNS and MR-SNe are necessary to match the observations; and (iii) our model slightly underpredicts Mo and Nd, while accurately reproducing the [Pr/Fe] versus [Fe/H] trend. Regarding the radial gradients, we find that: (i) our predicted [Fe/H] gradient slope agrees with observations from Gaia -ESO and other high-resolution spectroscopic surveys; (ii) the predicted [Eu/H] radial gradient slope is steeper than the observed one, regardless of how quick the production of Eu is, prompting discussion on different Galaxy-formation scenarios and stellar radial migration effects; and (iii) elements in the second s-process peak as well as Nd and Pr exhibit a plateau at low-Galactocentric distances, likely due to enhanced enrichment from LIMS in the inner regions. [ABSTRACT FROM AUTHOR]

Our knowledge of stellar evolution is driven by one-dimensional (1D) simulations. 1D models, however, are severely limited by uncertainties on the exact behaviour of many multidimensional phenomena occurring inside stars, affecting their structure and evolution. Recent advances in computing resources have allowed small sections of a star to be reproduced with multi-D hydrodynamic models, with an unprecedented degree of detail and realism. In this work, we present a set of 3D simulations of a convective neon-burning shell in a 20 M⊙ star run for the first time continuously from its early development through to complete fuel exhaustion, using unaltered input conditions from a 321D-guided 1D stellar model. These simulations help answer some open questions in stellar physics. In particular, they show that convective regions do not grow indefinitely due to entrainment of fresh material, but fuel consumption prevails over entrainment, so when fuel is exhausted convection also starts decaying. Our results show convergence between the multi-D simulations and the new 321D-guided 1D model, concerning the amount of convective boundary mixing to include in stellar models. The size of the convective zones in a star strongly affects its structure and evolution; thus, revising their modelling in 1D will have important implications for the life and fate of stars. This will thus affect theoretical predictions related to nucleosynthesis, supernova explosions, and compact remnants. [ABSTRACT FROM AUTHOR]

The assembly of supermassive black holes poses a challenge primarily because of observed quasars at high redshift, but additionally because of the current lack of observations of intermediate mass black holes. One plausible scenario for creating supermassive black holes is direct collapse triggered by the merger of two gas-rich galaxies. This scenario allows the creation of supermassive stars with solar metallicity. We investigate the behaviour of metal enriched supermassive stars which collapse due to the general relativistic radial instability during hydrogen burning. These stars contain both hydrogen and metals and thus may explode due to the CNO cycle (carbon–nitrogen–oxygen) and the rp process (rapid proton capture). We perform a suite of stellar evolution simulations for a range of masses and metallicities, with and without mass-loss. We evaluate the stability of these supermassive stars by solving the pulsation equation in general relativity. When the stars becomes unstable, we perform 1D general relativistic hydrodynamical simulations coupled to a 153 isotope nuclear network with cooling from neutrino reactions, in order to determine if the stars explode. If the stars do explode, we post process the nucleosynthesis using a 514 isotope network which includes additional proton rich isotopes. These explosions are characterized by enhanced nitrogen and intermediate mass elements (⁠|$16\ge \rm {A}\ge 25$|⁠), and suppressed light elements (⁠|$8\ge \rm {A}\ge 14$|⁠), and we comment on recent observations of super-solar nitrogen in GN-z11. [ABSTRACT FROM AUTHOR]

Theoretically predicted yields of elements created by the rapid neutron capture (r-)process carry potentially large uncertainties associated with incomplete knowledge of nuclear properties and approximative hydrodynamical modelling of the matter ejection processes. We present an in-depth study of the nuclear uncertainties by varying theoretical nuclear input models that describe the experimentally unknown neutron-rich nuclei. This includes two frameworks for calculating the radiative neutron capture rates and 14 different models for nuclear masses, β-decay rates, and fission properties. Our r-process nuclear network calculations are based on detailed hydrodynamical simulations of dynamically ejected material from NS–NS or NS–BH binary mergers plus the secular ejecta from BH–torus systems. The impact of nuclear uncertainties on the r-process abundance distribution and the early radioactive heating rate is found to be modest (within a factor of ∼20 for individual A > 90 abundances and a factor of 2 for the heating rate). However, the impact on the late-time heating rate is more significant and depends strongly on the contribution from fission. We witness significantly higher sensitivity to the nuclear physics input if only a single trajectory is used compared to considering ensembles with a much larger number of trajectories (ranging between 150 and 300), and the quantitative effects of the nuclear uncertainties strongly depend on the adopted conditions for the individual trajectory. We use the predicted Th/U ratio to estimate the cosmochronometric age of six metal-poor stars and find the impact of the nuclear uncertainties to be up to 2 Gyr. [ABSTRACT FROM AUTHOR]

We study the long-term (⁠|$t\gg 10\rm \, s\!$|) evolution of the accretion disc after a neutron star(NS)–NS or NS–black hole merger, taking into account the radioactive heating by r -process nuclei formed in the first few seconds. We find that the cumulative heating eventually exceeds the disc's binding energy at |$t\sim 10^2\mathrm{\, s}\, (\alpha /0.1)^{-1.8}(M/2.6\, \mathrm{M}_{\odot })^{1.8}$| after the merger, where α is the viscosity parameter and M is the mass of the remnant object. This causes the disc to evaporate rapidly and the jet power to shut off. We propose that this corresponds to the steep flux decline at the end of the extended emission (EE) or X-ray plateau seen in many short gamma-ray bursts (GRBs). The shallow flux evolution before the steep decline is consistent with a plausible scenario where the jet power scales linearly with the disc mass. We suggest that the jets from NS mergers have two components – a short-duration narrow one producing the prompt gamma-rays and a long-lasting wide component producing the EE. This leads to a prediction that 'orphan EE' (without short GRB) may be a promising electromagnetic counterpart for NS mergers observable by future wide-field X-ray surveys. The long-lived disc produces a slow ejecta component that can efficiently thermalize the β-electrons' energy up to |$t\sim 100\rm \, d$| and contributes |$\sim \!10~{{\ \rm per\ cent}}$| of the kilonova's bolometric luminosity at these late epochs. We predict that future ground-based and JWST near-IR spectroscopy of nearby (⁠|$\lesssim 100\rm \, Mpc\!$|) NS mergers will detect narrow (Δ v ∼ 0.01 c) line features a few weeks after the merger. [ABSTRACT FROM AUTHOR]

Coastal wetlands are naturally subjected to salinity, which is expected to increase through global climate changes. Most species will be affected by these changes, leading to major consequences for community structure and ecosystem functioning.We investigated variation of salinity of temporary wetlands across spatial (1,000 m from the ocean) and temporal (across three breeding season) scales relevant to coastal biodiversity and used amphibians (six species, sampled across one breeding season) as a model to investigate the consequences of the spatio‐temporal variation of salinity in 24 ponds situated on the Atlantic coast of France.We show that salinity is a highly dynamic environmental variable that varies widely both across spatial and temporal scales. The spatio‐temporal dynamics of salinity are a critical factor structuring amphibian communities that affect the main amphibian phylogenetic groups (caudates vs. anurans) differently. Temporal variation in salinity disrupts the match between salinity selected by reproductive adults and those experienced later by their developing offspring, which negatively affect reproductive success.Future changes in coastal salinity are likely to affect the structure and functioning of these ecosystems, excluding salt‐intolerant species and eventually leading to less diverse communities of salt‐tolerant species. [ABSTRACT FROM AUTHOR]

Ongoing MeV telescopes such as INTEGRAL/SPI and Fermi/GBM, and proposed telescopes including the recently accepted COSI and the e-ASTROGAM and AMEGO missions, provide another window in understanding transients. Their signals contain information about the stellar explosion mechanisms and their corresponding nucleosynthesis of short-lived radioactive isotopes. This raises the need of a radiative transfer code which may efficiently explore different types of astrophysical γ-ray sources and their dependence on model parameters and input physics. In view of this, we present our new Monte-Carlo Radiative Transfer code in python. The code synthesizes the γ-ray spectra and light curves suitable for modelling supernova ejecta, including C+O novae, O+Ne novae, Type Ia and core-collapse supernovae. We test the code extensively for reproducing results consistent with analytic models. We also compare our results with similar models in the literature and discuss how our code depends on selected input physics and setting. [ABSTRACT FROM AUTHOR]

Detection of kilonova AT2017gfo proves that binary neutron star mergers can be the dominant contributor to the production of heavy elements in our Universe. Neutrinos from the radioactive decay of heavy elements would be the most direct messengers of merger ejecta. Based on r -process nucleosynthesis calculations, we study the neutrinos emitted from the β-decay of r -process elements and find that about half of the β-decay energy is carried away by neutrinos. The neutrino energy generation rate remains approximately constant at the early stage (t ≲ 1 s) and then decays as a power-law function with an index of −1.3. This powers a short-lived fast neutrino burst with a peak luminosity of ∼1049 erg s−1 in the early stage. Observation of neutrinos from neutron star mergers will be an important step towards understanding the properties of extremely neutron-rich nuclei and r -process nucleosynthesis, since the dominant contribution to the early time neutrino production is from nuclides near the r -process path. The typical neutrino energy is ≲8 MeV, which is within the energy ranges of the water-Cherenkov neutrino detectors such as Super-Kamiokande and future Hyper-Kamiokande, but the extremely low neutrino flux and event rate in our local Universe challenge the detection of the neutrino flashes. [ABSTRACT FROM AUTHOR]

The cosmic production of the short-lived radioactive nuclide 26Al is crucial for our understanding of the evolution of stars and galaxies. However, simulations of the stellar sites producing 26Al are still weakened by significant nuclear uncertainties. We re-evaluate the 26Al(n, p)26Mg, and 26Al(n, α)23Na ground state reactivities from 0.01 GK to 10 GK, based on the recent n_TOF measurement combined with theoretical predictions and a previous measurement at higher energies, and test their impact on stellar nucleosynthesis. We computed the nucleosynthesis of low- and high-mass stars using the Monash nucleosynthesis code, the NuGrid mppnp code, and the FUNS stellar evolutionary code. Our low-mass stellar models cover the 2–3 M⊙ mass range with metallicities between Z =  0.01 and 0.02, their predicted 26Al/27Al ratios are compared to 62 meteoritic SiC grains. For high-mass stars, we test our reactivities on two 15 M⊙ models with Z =  0.006 and 0.02. The new reactivities allow low-mass AGB stars to reproduce the full range of 26Al/27Al ratios measured in SiC grains. The final 26Al abundance in high-mass stars, at the point of highest production, varies by a factor of 2.4 when adopting the upper, or lower limit of our rates. However, stellar uncertainties still play an important role in both mass regimes. The new reactivities visibly impact both low- and high-mass stars nucleosynthesis and allow a general improvement in the comparison between stardust SiC grains and low-mass star models. Concerning explosive nucleosynthesis, an improvement of the current uncertainties between T9∼0.3 and 2.5 is needed for future studies. [ABSTRACT FROM AUTHOR]

Context. The presence of radioactive 26Al at 1.8MeV reveals an ongoing process of nucleosynthesis in the Milky Way. Diffuse emission from its decay can be measured with gamma-ray telescopes in space. The intensity, line shape, and spatial distribution of the 26Al emission allow for studies of these nucleosynthesis sources. The line parameters trace massive-star feedback in the interstellar medium thanks to its 1 My lifetime. Aims. We aim to expand upon previous studies of the 26Al emission in the Milky Way, using all available gamma-ray data, including single and double events collected with SPI on INTEGRAL from 2003 until 2020. Methods. We applied improved spectral response and background as evaluated from tracing spectral details over the entire mission. The exposure for the Galactic 26Al emission was enhanced using all event types measured within SPI. We redetermined the intensity of Galactic 26Al emission across the entire sky, through maximum likelihood fits of simulated and model-built sky distributions to SPI spectra for single and for double detector hits. Results. We found an all-sky flux of (1.84±0.03)×10-3 ph cm-2 s-1 in the 1.809 MeV line from 26Al, determined via fitting to sky distributions from previous observations with COMPTEL. Significant emission from higher latitudes indicates an origin from nearby massive-star groups and superbubbles, which is also supported by a bottom-up population synthesis model. The line centroid is found at (1809.83±0.04 keV), while the line broadening from source kinematics integrated over the sky is (0.62±0.3) keV (FWHM). [ABSTRACT FROM AUTHOR]

Diffuse 1-ray line emission traces freshly produced radioisotopes in the interstellar gas, providing a unique perspective on the entire Galactic cycle of matter from nucleosynthesis in massive stars to their ejection and mixing in the interstellar medium (ISM). We aim to construct a model of nucleosynthesis ejecta on a galactic scale that is specifically tailored to complement the physically most important and empirically accessible features of 1ray measurements in the MeV range, in particular for decay 1 rays such as 26Al, 60Fe, or 44Ti. Based on properties of massive star groups, we developed a Population SYnthesis COde (PSYCO), which can instantiate galaxy models quickly and based on many different parameter configurations, such as the star formation rate (SFR), density profiles, or stellar evolution models. As a result, we obtain model maps of nucleosynthesis ejecta in the Galaxy which incorporate the population synthesis calculations of individual massive star groups. Based on a variety of stellar evolution models, supernova (SN) explodabilities, and density distributions, we find that the measured 26Al distribution from INTEGRAL/SPI can be explained by a Galaxy-wide population synthesis model with a SFR of 4-8 M yr-1 and a spiral-arm-dominated density profile with a scale height of at least 700 pc. Our model requires that most massive stars indeed undergo a SN explosion. This corresponds to a SN rate in the Milky Way of 1.8-2.8 per century, with quasi-persistent 26Al and 60Fe masses of 1.2-2.4 Mand 1-6 M, respectively. Comparing the simulated morphologies to SPI data suggests that a frequent merging of superbubbles may take place in the Galaxy, and that an unknown yet strong foreground emission at 1.8MeV could be present. [ABSTRACT FROM AUTHOR]

Context. Barium (Ba) stars are characterised by an abundance of heavy elements made by the slow neutron capture process (s-process). This peculiar observed signature is due to the mass transfer from a stellar companion, bound in a binary stellar system, to the Ba star observed today. The signature is created when the stellar companion is an asymptotic giant branch (AGB) star. Aims. We aim to analyse the abundance pattern of 169 Ba stars using machine learning techniques and the AGB final surface abundances predicted by the FRUITY and Monash stellar models. Methods. We developed machine learning algorithms that use the abundance pattern of Ba stars as input to classify the initial mass and metallicity of each Ba star's companion star using stellar model predictions. We used two algorithms. The first exploits neural networks to recognise patterns, and the second is a nearest-neighbour algorithm that focuses on finding the AGB model that predicts the final surface abundances closest to the observed Ba star values. In the second algorithm, we included the error bars and observational uncertainties in order to find the best-fit model. The classification process was based on the abundances of Fe, Rb, Sr, Zr, Ru, Nd, Ce, Sm, and Eu. We selected these elements by systematically removing s-process elements from our AGB model abundance distributions and identifying the elements whose removal had the biggest positive effect on the classification. We excluded Nb, Y, Mo, and La. Our final classification combined the output of both algorithms to identify an initial mass and metallicity range for each Ba star companion. Results. With our analysis tools, we identified the main properties for 166 of the 169 Ba stars in the stellar sample. The classifications based on both stellar sets of AGB final abundances show similar distributions, with an average initial mass of M = 2.23 Mand 2.34 M and an average [Fe/H] = -0.21 and -0.11, respectively. We investigated why the removal of Nb, Y, Mo, and La improves our classification and identified 43 stars for which the exclusion had the biggest effect. We found that these stars have statistically significant and different abundances for these elements compared to the other Ba stars in our sample. We discuss the possible reasons for these differences in the abundance patterns. [ABSTRACT FROM AUTHOR]

We present a systematic numerical relativity study of the impact of different physics input and grid resolution in binary neutron star mergers. We compare simulations employing a neutrino leakage scheme, leakage plus M0 scheme, the M1 transport scheme, and pure hydrodynamics. Additionally, we examine the effect of a sub-grid scheme for turbulent viscosity. We find that the overall dynamics and thermodynamics of the remnant core are robust, implying that the maximum remnant density could be inferred from gravitational wave observations. Black hole collapse instead depends significantly on viscosity and grid resolution. Differently from recent work, we identify possible signatures of neutrino effects in the gravitational waves only at the highest resolutions considered; new high-resolution simulations will be thus required to build accurate gravitational wave templates to observe these effects. Different neutrino transport schemes impact significantly mass, geometry, and composition of the remnant's disc and ejecta; M1 simulations show systematically larger proton fractions, reaching maximum values larger than 0.4. r-process nucleosynthesis yields reflect the different ejecta compositions; they are in agreement and reproduce residual solar abundances only if M0 or M1 neutrino transport schemes are adopted. We compute kilonova light curves using spherically-symmetric radiation-hydrodynamics evolutions up to 15 d post-merger, finding that they are mostly sensitive to the ejecta mass and electron fraction; accounting for multiple ejecta components appears necessary for reliable light curve predictions. We conclude that advanced neutrino schemes and resolutions higher than current standards are essential for robust long-term evolutions and detailed astrophysical predictions. [ABSTRACT FROM AUTHOR]

We present the first high-resolution chemical abundances of seven stars in the recently discovered high-energy stream Typhon. Typhon stars have apocentres r ≳ 100 kpc, making this the first detailed chemical picture of the Milky Way's very distant stellar halo. Though the sample size is limited, we find that Typhon's chemical abundances are more like a dwarf galaxy than a globular cluster, showing a metallicity dispersion and no presence of multiple stellar populations. Typhon stars display enhanced α-element abundances and increasing r -process abundances with increasing metallicity. The high-α abundances suggest a short star formation duration for Typhon, but this is at odds with expectations for the distant Milky Way halo and the presence of delayed r -process enrichment. If the progenitor of Typhon is indeed a new dwarf galaxy, possible scenarios explaining this apparent contradiction include a dynamical interaction that increases Typhon's orbital energy, a burst of enhanced late-time star formation that raises [α/Fe], and/or group pre-processing by another dwarf galaxy before infall into the Milky Way. Alternatively, Typhon could be the high-energy tail of a more massive disrupted dwarf galaxy that lost energy through dynamical friction. We cannot clearly identify a known low-energy progenitor of Typhon in the Milky Way, but 70 per cent of high-apocentre stars in cosmological simulations are from high-energy tails of large dwarf galaxies. Typhon's surprising combination of kinematics and chemistry thus underscores the need to fully characterize the dynamical history and detailed abundances of known substructures before identifying the origin of new substructures. [ABSTRACT FROM AUTHOR]

We present a numerical parameter survey of sub-Chandrasekhar mass white dwarf (WD) explosions. Carbon-oxygen WDs accreting a helium shell have the potential to explode in the sub-Chandrasekhar mass regime. Previous studies have shown how the ignition of a helium shell can either directly ignite the WD at the core-shell interface or propagate a shock wave into the the core causing a central ignition. We examine the explosions of WDs from 0.6 to 1.2 M o with helium shells of 0.01, 0.05, and 0.08 M o . Distinct observational signatures of sub-Chandrasekhar mass WD explosions are predicted for two categories of shell size. Thicker-shell models show an early time flux excess, which is caused by the presence of radioactive material in the ashes of the helium shell, and red colors due to these ashes creating significant line blanketing in the UV through the blue portion of the spectrum. Thin shell models reproduce several typical Type Ia supernova signatures. We identify a relationship between Si ii velocity and luminosity that, for the first time, identifies a subclass of observed supernovae that are consistent with these models. This subclass is further delineated by the absence of carbon in their atmospheres. We suggest that the proposed difference in the ratio of selective to total extinction between the high velocity and normal velocity Type Ia supernovae is not due to differences in the properties of the dust around these events, but is rather an artifact of applying a single extinction correction to two intrinsically different populations of supernovae.

Abstract Background Individuals with type 1 diabetes and those with depression show differences in the composition of the gut microbiome from that of healthy people. However, these differences have not yet been studied in patients with both diseases. Therefore, we compared the gut microbiome of people with type 1 diabetes with or without depression with matched healthy controls. Methods A case-control study was conducted in 20 adults with type 1 diabetes (group A), 20 adults with type 1 diabetes and depression (group B), and 20 healthy adults (group C). Gut microbiota composition was determined by sequencing of the V3-V4 region of the bacterial 16S rDNA and alpha and beta diversity was compared between the groups. Results Groups A and B both showed higher alpha diversity than the healthy control group (P

Fast neutrino (ν)-flavour conversion (FFC) is a possible game-changing ingredient in core-collapse supernova (CCSN) theory. In this paper, we examine the impact of FFC on explosive nucleosynthesis by including the effects of FFC in conjunction with asymmetric ν emission into nucleosynthetic computations in a parametric way. We find that the ejecta compositions are not appreciably affected by FFC for elements lighter than Co while the compositions are influenced by FFC for the heavier elements. We also find that the role of FFC varies depending on the asymmetric degree of ν emission (m asy) and the degree of ν-flavour mixing. The impact of FFC is not monotonic to m asy. The change in the ejecta composition increases for higher m asy up to ∼10 per cent compared with that without FFC, whereas FFC has little effect on the nucleosynthesis in very large asymmetric ν emission (⁠|${\gtrsim}30\,\hbox{per cent}$|⁠). Our results suggest that FFC facilitates the production of neutron-rich ejecta in most cases, although it makes the ejecta more proton-rich if anti-ν conversion is more vigorous than that of ν. The key ingredient accounting for this trend is ν absorption, whose effects on nucleosynthesis can be quantified by simple diagnostics. [ABSTRACT FROM AUTHOR]

We study a sample of single Galactic post-asymptotic giant branch (post-AGB) stars with known surface chemical composition. Gaia   EDR3 and Gaia   DR3 parallaxes have enabled accurate determinations of the luminosities of these objects, thus making it possible to characterize them in terms of their initial masses, chemical compositions, and progenitor ages. We used extant evolutionary sequences of asymptotic giant branch (AGB) stars produced using the ATON stellar evolutionary code extended to the post-AGB phase, specifically for this study. The luminosity and surface carbon abundance together prove to be the most valuable indicator of the previous evolution and nucleosynthetic history of the star, particularly regarding the efficiency of mixing mechanisms and the growth of the core. This analysis allows us to place the post-AGB sample into classes based on their evolutionary history on the AGB. This includes low-mass objects that evolved as M-type stars without third dredge-up, carbon stars, and intermediate-mass AGB stars with hot bottom burning (HBB). Additionally, our analysis reveals that AGB nucleosynthesis is not homogeneous, even for stars with similar initial masses and metallicities. The approach of using observations of post-AGB stars to constrain AGB and post-AGB models shed new light on still debated issues related to the AGB evolution, such as the threshold mass required to become a C-star, the minimum mass for HBB and the amount of carbon that can be accumulated in the surface regions of the star during the AGB lifetime, as well as deep mixing experienced during the red giant branch phase. [ABSTRACT FROM AUTHOR]

We present detailed chemical compositions of four stars on the first-ascent red giant branch that are classified as chemically peculiar, but lack comprehensive analyses at high spectral resolution. For BD+03°2688, HE 0457−1805, HE 1255−2324, and HE 2207−1746, we derived metallicities [Fe/H] = −1.21, −0.19, −0.31, and −0.55, respectively, indicating a range in Galactic population membership. In addition to atmospheric parameters, we extracted elemental abundances for 28 elements, including the evolutionary-sensitive CNO group and 12C/13C ratios. Novel results are also presented for the heavy elements tungsten and thallium. All four stars have very large enhancements of neutron-capture elements, with high [La/Eu] ratios indicating enrichments from the slow neutron capture (s -process). To interpret these abundances, all indicative of [ s /Fe] >1.0, we compared our results with data from literature, as well as with predictions from the Monash and fruity   s -process nucleosynthesis models. BD+03°2688, HE 1255−2324, and HE 2207−1746 show C/O >1, while HE 0457−1805 has C/O <1. Since HE 0457−1805 and HE 1255−2324 are binary stars, their peculiarities are attributable to mass transfer. We identified HE 0457−1805 as a new barium giant star, and HE 1255−2324 as a new CH star, in fact a higher metallicity analogue CEMP- r / s star; the single object reported in literature so far with similar characteristics is the barium star HD 100503 ([Fe/H] = −0.72). A systematic monitoring is needed to confirm the binary nature of BD+03°2688 and HE 2207−1746, which are probably CH stars. [ABSTRACT FROM AUTHOR]

We investigate r -process nucleosynthesis and kilonova emission resulting from binary neutron star (BNS) mergers based on a three-dimensional (3D) general-relativistic magnetohydrodynamic (GRMHD) simulation of a hypermassive neutron star (HMNS) remnant. The simulation includes a microphysical finite-temperature equation of state (EOS) and neutrino emission and absorption effects via a leakage scheme. We track the thermodynamic properties of the ejecta using Lagrangian tracer particles and determine its composition using the nuclear reaction network SkyNet. We investigate the impact of neutrinos on the nucleosynthetic yields by varying the neutrino luminosities during post-processing. The ejecta show a broad distribution with respect to their electron fraction Ye , peaking between ∼0.25–0.4 depending on the neutrino luminosity employed. We find that the resulting r -process abundance patterns differ from solar, with no significant production of material beyond the second r -process peak when using luminosities recorded by the tracer particles. We also map the HMNS outflows to the radiation hydrodynamics code SNEC and predict the evolution of the bolometric luminosity as well as broadband light curves of the kilonova. The bolometric light curve peaks on the timescale of a day and the brightest emission is seen in the infrared bands. This is the first direct calculation of the r -process yields and kilonova signal expected from HMNS winds based on 3D GRMHD simulations. For longer-lived remnants, these winds may be the dominant ejecta component producing the kilonova emission. [ABSTRACT FROM AUTHOR]

Jupiter's atmospheric water abundance is a highly important cosmochemical parameter that is linked to processes of planetary formation, weather, and circulation. Remote sensing and in situ measurement attempts still leave room for substantial improvements to our knowledge of Jupiter's atmospheric water abundance. With the motivation to advance our understanding of water in Jupiter's atmosphere, we investigate observations and models of deep clouds. We discuss deep clouds in isolated convective storms (including a unique storm site in the North Equatorial Belt that episodically erupted in 2021–2022), cyclonic vortices, and northern high-latitude regions, as seen in Hubble Space Telescope visible/near-infrared imaging data. We evaluate the imaging data in continuum and weak methane band (727 nm) filters by comparison with radiative transfer simulations, 5 micron imaging (Gemini), and 5 micron spectroscopy (Keck), and conclude that the weak methane band imaging approach mostly detects variation in the upper cloud and haze opacity, although sensitivity to deeper cloud layers can be exploited if upper cloud/haze opacity can be separately constrained. The cloud-base water abundance is a function of cloud-base temperature, which must be estimated by extrapolating 0.5-bar observed temperatures downward to the condensation region near 5 bar. For a given cloud base pressure, the largest source of uncertainty on the local water abundance comes from the temperature gradient used for the extrapolation. We conclude that spatially resolved spectra to determine cloud heights—collected simultaneously with spatially-resolved mid-infrared spectra to determine 500-mbar temperatures and with improved lapse rate estimates—would be needed to answer the following very challenging question: Can observations of deep water clouds on Jupiter be used to constrain the atmospheric water abundance? [ABSTRACT FROM AUTHOR]

How are the heavy elements formed? This has been a key open question in physics for decades. Recent direct detections of neutron star mergers and observations of evolved stars show signatures of chemical elements in the blue range of their spectra that bear witness of recent nuclear processes that led to heavy element production. The formation of heavy elements typically takes place through neutron-capture reactions creating radioactive isotopes, which following beta-decay turn into the stable isotopes we today can measure indirectly in the surfaces of cool, low-mass stars or meteoritic grains. The conditions (such as the neutron density or entropy) of these n-capture reactions remain to date poorly constrained, and only through a multidisciplinary effort can we, by combining and comparing observations, experiments, and theoretical predictions, improve on one of the top 10 most important open physics questions posed at the turn of the century. This emphasises the need for detailed observations of the near-UV to blue wavelength region. The shortage of spectrographs and hence spectra covering this range with high-resolution and high signal-to-noise has for decades played a limiting factor in our understanding of how heavy elements form in the nuclear reactions as well as how they behave in the stellar surfaces. With CUBES (Cassegrain U-Band Efficient Spectrograph) we can finally improve the observations, by covering the crucial blue range in more remote stars and also achieve a higher signal-to-noise ratio (SNR). This is much needed to detect and accurately deblend the absorption lines and in turn derive more accurate and precise abundances of the heavy elements. [ABSTRACT FROM AUTHOR]

The radioisotope 44Ti is produced through α-rich freezeout and explosive helium burning in type Ia supernovae (SNe Ia). In this paper, we discuss how the detection of 44Ti, either through late-time light curves of SNe Ia, or directly via gamma-rays, can uniquely constrain the origin of SNe Ia. In particular, building upon recent advances in the hydrodynamical simulation of helium-ignited double white dwarf binaries, we demonstrate that the detection of 44Ti in a nearby SN Ia or in a young Galactic supernova remnant (SNR) can discriminate between the double-detonation and double-degenerate channels of sub-Chandrasekhar (sub- M Ch) and near-Chandrasekhar (near- M Ch) SNe Ia. In addition, we predict that the late-time light curves of calcium-rich transients are entirely dominated by 44Ti. [ABSTRACT FROM AUTHOR]

Thermal bombs are a widely used method to artificially trigger explosions of core-collapse supernovae (CCSNe) to determine their nucleosynthesis or ejecta and remnant properties. Recently, their use in spherically symmetric (1D) hydrodynamic simulations led to the result that 56,57Ni and 44Ti are massively underproduced compared to observational estimates for Supernova 1987A, if the explosions are slow, i.e. if the explosion mechanism of CCSNe releases the explosion energy on long time-scales. It was concluded that rapid explosions are required to match observed abundances, i.e. the explosion mechanism must provide the CCSN energy nearly instantaneously on time-scales of some ten to order 100 ms. This result, if valid, would disfavour the neutrino-heating mechanism, which releases the CCSN energy on time-scales of seconds. Here, we demonstrate by 1D hydrodynamic simulations and nucleosynthetic post-processing that these conclusions are a consequence of disregarding the initial collapse of the stellar core in the thermal-bomb modelling before the bomb releases the explosion energy. We demonstrate that the anticorrelation of 56Ni yield and energy-injection time-scale vanishes when the initial collapse is included and that it can even be reversed, i.e. more 56Ni is made by slower explosions, when the collapse proceeds to small radii similar to those where neutrino heating takes place in CCSNe. We also show that the 56Ni production in thermal-bomb explosions is sensitive to the chosen mass cut and that a fixed mass layer or fixed volume for the energy deposition cause only secondary differences. Moreover, we propose a most appropriate setup for thermal bombs. [ABSTRACT FROM AUTHOR]

Here, we present calculations on the energy delivered (and heating) by realistic cosmic rays (CRs) field at a typical molecular clump. The current model describes, with unprecedented spatial resolution, the energy delivery by a realistic CR field in molecular clumps. The calculations were performed employing the Geant4 code (considering full cascade physical processes and hadron physics) considering the cosmic ray field taken from the Voyager spacecraft measurements in the interstellar medium. The results showed that the total energy deposition rate, considering light particles (protons, electrons and alphas), medium-mass ions and heavy-ions, ranges from 400 MeV/g/s in the outer layer (at 105 AU) to roughly 100 MeV/g/s in the inner layer of the model (below 0.1 AU). The main energy deposition rate is due to the incoming protons. Incoming alphas represent 15–20 per cent of the energy deposition. In the deep core of the cloud, the fraction of energy delivered by medium-mass ions, electrons, and heavy ions are 5 per cent, 2.5 per cent, and 1 per cent, respectively. The heating induced by cosmic rays seems to affect mostly the regions above ∼500 AU. Considering a balanced heat model with warm dust grains (T∼16–18 K), we observe a small bump in temperature at 2000–5000 AU. We suggest this temperature enhancement by CRs might have some affect on the molecular formation or cometary formation in pristine Oort cloud region inside the Solar System. [ABSTRACT FROM AUTHOR]

Magnetorotational supernovae are a rare type of core-collapse supernovae where the magnetic field and rotation play a central role in the dynamics of the explosion. We present the post-processed nucleosynthesis of state-of-the-art neutrino-MHD supernova models that follow the post explosion evolution for few seconds. We find three different dynamical mechanisms to produce heavy r-process elements: (i) a prompt ejection of matter right after core bounce, (ii) neutron-rich matter that is ejected at late times due to a reconfiguration of the protoneutronstar shape, (iii) small amount of mass ejected with high entropies in the centre of the jet. We investigate total ejecta yields, including the ones of unstable nuclei such as 26Al, 44Ti, 56Ni, and 60Fe. The obtained 56Ni masses vary between |$0.01\!-\!1\, \mathrm{M_\odot }$|⁠. The latter maximum is compatible with hypernova observations. Furthermore, all of our models synthesize Zn masses in agreement with observations of old metal-poor stars. We calculate simplified light curves to investigate whether our models can be candidates for superluminous supernovae. The peak luminosities obtained from taking into account only nuclear heating reach up to a few |$\sim 10^{43} \, \mathrm{erg\, s^{-1}}$|⁠. Under certain conditions, we find a significant impact of the 66Ni decay chain that can raise the peak luminosity up to |$\sim 38{{\ \rm per \, cent}}$| compared to models including only the 56Ni decay chain. This work reinforces the theoretical evidence on the critical role of magnetorotational supernovae to understand the occurrence of hypernovae, superluminous supernovae, and the synthesis of heavy elements. [ABSTRACT FROM AUTHOR]

Nuclear reaction rates are a fundamental yet uncertain ingredient in stellar evolution models. The astrophysical S -factor pertaining to the initial reaction in the proton–proton (pp) chain is uncertain at the 1 per cent level, which contributes a systematic but generally unpropagated error of similar order in the theoretical ages of stars. In this work, we study the prospect of improving the measurement of this and other reaction rates in the pp chain and CNO cycle using helioseismology and solar neutrinos. We show that when other aspects of the solar model are improved, then it shall be possible using current solar data to improve the precision of this measurement by nearly an order of magnitude and hence the corresponding uncertainty on the ages of low-mass stars by a similar amount. [ABSTRACT FROM AUTHOR]

We analyse new multifilter Hubble Space Telescope (HST) photometry of the normal Type Ia supernova (SN Ia) 2011fe out to ≈2400 d after maximum light, the latest observations to date of a SN Ia. We model the pseudo-bolometric light curve with a simple radioactive decay model and find energy input from both 57Co and 55Fe are needed to power the late-time luminosity. This is the first detection of 55Fe in a SN Ia. We consider potential sources of contamination such as a surviving companion star or delaying the deposition time-scale for 56Co positrons but these scenarios are ultimately disfavored. The relative isotopic abundances place direct constraints on the burning conditions experienced by the white dwarf (WD). Additionally, we place a conservative upper limit of <10−3 M⊙ on the synthesized mass of 44Ti. Only two classes of explosion models are currently consistent with all observations of SN 2011fe: (1) the delayed detonation of a low-ρ c , near- M Ch (1.2–1.3 M⊙) WD, or (2) a sub- M Ch (1.0–1.1 M⊙) WD experiencing a thin-shell double detonation. [ABSTRACT FROM AUTHOR]

Certain types of silicon carbide (SiC) grains, e.g. SiC-X grains, and low density (LD) graphites are C-rich presolar grains that are thought to have condensed in the ejecta of core-collapse supernovae (CCSNe). In this work, we compare C, N, Al, Si, and Ti isotopic abundances measured in presolar grains with the predictions of 21 CCSN models. The impact of a range of SN explosion energies is considered, with the high energy models favouring the formation of a C/Si zone enriched in 12C, 28Si, and 44Ti. Eighteen of the 21 models have H ingested into the He-shell and different abundances of H remaining from such H-ingestion. CCSN models with intermediate to low energy (that do not develop a C/Si zone) cannot reproduce the 28Si and 44Ti isotopic abundances in grains without assuming mixing with O-rich CCSN ejecta. The most 28Si-rich grains are reproduced by energetic models when material from the C/Si zone is mixed with surrounding C-rich material, and the observed trends of the 44Ti/48Ti and 49Ti/48Ti ratios are consistent with the C-rich C/Si zone. For the models with H-ingestion, high and intermediate explosion energies allow the production of enough 26Al to reproduce the 26Al/27Al measurements of most SiC-X and LD graphites. In both cases, the highest 26Al/27Al ratio is obtained with H still present at X H ≈ 0.0024 in He-shell material when the SN shock is passing. The existence of H in the former convective He-shell points to late H-ingestion events in the last days before massive stars explode as a supernova. [ABSTRACT FROM AUTHOR]

A quantitative analysis of the spectrum of HD 108564 is performed. It is a star of the main sequence of spectral class K5V, the atmosphere of which is depleted in metals. The high-quality observed HARPS spectra are downloaded from the ESO archive. Abundances of elements in the atmosphere are obtained by fit of observational profiles of the C I lines and selected lines of the C2 molecules, and the O I, Ca I, Si I, Sc II, Cr I, CI, OI, Na I, Mg I, Si I, Ca I, Sc II, Ti I, Ti II, Cr I, Mn I, Fe I, Fe II, Co I, Ni I, Cu I, and Zn I. Abundances are determined iteratively, with a recalculation of the input parameters, which are effective temperature Teff at a fixed value of gravity logg (or log g for a fixed Teff value). The effect of variations of Teff or log g, which provide the same abundances of A(Fe I) and A(Fe II), on the abundances of other elements are determined. The obtained results indicate an excess of light elements (C, O, and Si) compared to the group of iron. The absence of the lithium line at 670.8 nm is confirmed with an estimate of A(Li) < –12.5 for the upper limit of lithium abundance in the abundance scale, in which the sum of all abundances is 1.0. The determined radial velocity equal to Vrad = 111.21 km/s is consistent with the known estimates of other researchers. Apparent rotation velocity V sin i = 1.12 ± 0.5 km/s is determined. [ABSTRACT FROM AUTHOR]

Local geological and tectonic processes have been pivotal in shaping the diverse sedimentation patterns observed in Jordan, forming sub-basins characterized by elevated organic matter content (TOC). This study aims to characterize the Maastrichtian basin, focusing on sedimentation rates using calcareous nannofossils and understanding paleoecological and paleo-oceanic conditions. It offers insights into the paleoenvironmental factors impacting oil shale deposition in the late Maastrichtian–Paleocene period. It employs classical biostratigraphical, semi-quantitative, and statistical methodologies to achieve its objectives of age determination and paleoecological insights. A total of 116 smear slides from two sites were obtained: the first, consisting of WA-1 (23 samples), WA-2 (18 samples), and WA-3 (11 samples), and the second, with 60 samples. Notably, the sites exhibit varying topography. WA-1 and WA-2, situated at lower elevations, have the highest Total Organic Carbon (TOC) levels, while areas with higher elevations in section four are visually identified by a light color. The study revealed varying patterns of calcareous nannofossil richness in the two investigated sites. These patterns were instrumental in defining biozones, with the utilization of marker species such as Lithraphidites quadratus, Micula murus, Micula prinsii, and Cruciplacolithus tenuis. Chronologically, these sections were classified as Maastrichtian–Paleogene, encompassing the following biozones in sequential order: UC-20a, UC-20b, UC-20c, UC-20d, and NP-2. Furthermore, the study identified two hiatus intervals, observed in sections WA-1 and KAS-1. The absence of certain biozones in the analyzed sections suggests that these sections correspond to distinct geological blocks within the basin, underscoring the role of tectonic forces during the deposition period. The sedimentation rate initially commenced at low levels but gradually increased due to topographic alterations. Notably, the biozone UC-20c demonstrated a clear trend toward warming and enhanced nutrient availability. In this context, the abundance and diversity of species were associated with increased continental influx into the sub-basin, resulting in rising nutrient levels and the number of calcareous nannofossils. This study enhances the understanding of the local and global effects such as tectonic and climates of the continuity of basins by deciphering calcareous nannofossil patterns and their correlation with sedimentation factors.

Abstract: We present shell model calculations of nuclear neutrino energy spectra for 70 sd-shell nuclei over the mass number range A = 21–35. Our calculations include nuclear excited states as appropriate for the hot and dense conditions characteristic of pre-collapse massive stars. We consider neutrinos produced by charged lepton captures and decays, and for the first time in tabular form, neutral current nuclear deexcitation, providing neutrino energy spectra on the Fuller–Fowler–Newman temperature–density grid for these interaction channels for each nucleus. We use the full sd-shell model space to compute initial nuclear states up to 20 MeV excitation with transitions to final states up to 35–40 MeV, employing a modification of the Brink-Axel hypothesis to handle high-temperature population factors and the nuclear partition functions.

GW190425 was the second gravitational wave (GW) signal compatible with a binary neutron star (BNS) merger detected by the Advanced LIGO and Advanced Virgo detectors. Since no electromagnetic counterpart was identified, whether the associated kilonova was too dim or the localization area too broad is still an open question. We simulate 28 BNS mergers with the chirp mass of GW190425 and mass ratio 1 ≤ q ≤ 1.67, using numerical-relativity simulations with finite-temperature, composition dependent equations of state (EOS) and neutrino radiation. The energy emitted in GWs is |$\lesssim 0.083\mathrm{\, M_\odot }c^2$| with peak luminosity of 1.1– |$2.4\times ~10^{58}/(1+q)^2\, {\rm {erg \, s^{-1}}}$|⁠. Dynamical ejecta and disc mass range between 5 × 10−6–10−3 and 10−5– |$0.1 \mathrm{\, M_\odot }$|⁠ , respectively. Asymmetric mergers, especially with stiff EOSs, unbind more matter and form heavier discs compared to equal mass binaries. The angular momentum of the disc is 8– |$10\mathrm{\, M_\odot }~GM_{\rm {disc}}/c$| over three orders of magnitude in M disc. While the nucleosynthesis shows no peculiarity, the simulated kilonovae are relatively dim compared with GW170817. For distances compatible with GW190425, AB magnitudes are always dimmer than ∼20 mag for the B, r , and K bands, with brighter kilonovae associated to more asymmetric binaries and stiffer EOSs. We suggest that, even assuming a good coverage of GW190425's sky location, the kilonova could hardly have been detected by present wide-field surveys and no firm constraints on the binary parameters or EOS can be argued from the lack of the detection. [ABSTRACT FROM AUTHOR]

After hydrogen and helium, oxygen, carbon, and nitrogen—hereinafter, the CNO elements—are the most abundant species in the universe. They are observed in all kinds of astrophysical environments, from the smallest to the largest scales, and are at the basis of all known forms of life, hence, the constituents of any biomarker. As such, their study proves crucial in several areas of contemporary astrophysics, extending to astrobiology. In this review, I will summarize current knowledge about CNO element evolution in galaxies, starting from our home, the Milky Way. After a brief recap of CNO synthesis in stars, I will present the comparison between chemical evolution model predictions and observations of CNO isotopic abundances and abundance ratios in stars and in the gaseous matter. Such a comparison permits to constrain the modes and time scales of the assembly of galaxies and their stellar populations, as well as stellar evolution and nucleosynthesis theories. I will stress that chemical evolution models must be carefully calibrated against the wealth of abundance data available for the Milky Way before they can be applied to the interpretation of observational datasets for other systems. In this vein, I will also discuss the usefulness of some key CNO isotopic ratios as probes of the prevailing, galaxy-wide stellar initial mass function in galaxies where more direct estimates from the starlight are unfeasible. [ABSTRACT FROM AUTHOR]