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Abstract Thailand–UK Python+Astronomy Summer School (ThaiPASS), a collaborative project comprising UK and Thai institutions and assess its impact and possible application to schools in the United Kingdom. Since its inception in 2018, the annual ThaiPASS has trained around 60 Thai high-school students in basic data handling skills using Python in the context of various astronomy topics, using current research from the teaching team. Our impact assessment of the 5 day summer schools shows an overwhelmingly positive response from students in both years, with over 80% of students scoring the activities above average in all activities butmore » -
ABSTRACT Several anomalous elemental abundance ratios have been observed in the metal-poor star HD94028. We assume that its high [As/Ge] ratio is a product of a weak intermediate (i) neutron-capture process. Given that observational errors are usually smaller than predicted nuclear physics uncertainties, we have first set-up a benchmark one-zone i-process nucleosynthesis simulation results of which provide the best fit to the observed abundances. We have then performed Monte Carlo simulations in which 113 relevant (n,γ) reaction rates of unstable species were randomly varied within Hauser–Feshbach model uncertainty ranges for each reaction to estimate the impact on the predicted stellarmore »
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Context. A realistic parametrization of convection and convective boundary mixing in conventional stellar evolution codes is still the subject of ongoing research. To improve the current situation, multidimensional hydrodynamic simulations are used to study convection in stellar interiors. Such simulations are numerically challenging, especially for flows at low Mach numbers which are typical for convection during early evolutionary stages. Aims. We explore the benefits of using a low-Mach hydrodynamic flux solver and demonstrate its usability for simulations in the astrophysical context. Simulations of convection for a realistic stellar profile are analyzed regarding the properties of convective boundary mixing. Methods. Themore »Free, publicly-accessible full text available September 1, 2022
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Context. Young open clusters (ages of less than 200 Myr) have been observed to exhibit several peculiarities in their chemical compositions. These anomalies include a slightly sub-solar iron content, super-solar abundances of some atomic species (e.g. ionised chromium), and atypical enhancements of [Ba/Fe], with values up to ~0.7 dex. Regarding the behaviour of the other s -process elements like yttrium, zirconium, lanthanum, and cerium, there is general disagreement in the literature: some authors claim that they follow the same trend as barium, while others find solar abundances at all ages. Aims. In this work we expand upon our previous analysismore »Free, publicly-accessible full text available September 1, 2022
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ABSTRACT Stellar and supernova nucleosynthesis in the first few billion years of the cosmic history have set the scene for early structure formation in the Universe, while little is known about their nature. Making use of stellar physical parameters measured by GALAH Data Release 3 with accurate astrometry from the Gaia EDR3, we have selected ∼100 old main-sequence turn-off stars (ages ≳12 Gyr) with kinematics compatible with the Milky Way stellar halo population in the Solar neighbourhood. Detailed homogeneous elemental abundance estimates by GALAH DR3 are compared with supernova yield models of Pop III (zero-metal) core-collapse supernovae (CCSNe), normal (non-zero-metal) CCSNe,more »
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Context. Grids of stellar models, computed with the same physical ingredients, allow one to study the impact of a given physics on a broad range of initial conditions and they are a key ingredient for modeling the evolution of galaxies. Aims. We present here a grid of single star models for masses between 0.8 and 120 M ⊙ , with and without rotation for a mass fraction of heavy element Z = 0.006, representative of the Large Magellanic Cloud (LMC). Methods. We used the GENeva stellar Evolution Code. The evolution was computed until the end of the central carbon-burning phase, themore »
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Context. NGC 6522 is a moderately metal-poor bulge globular cluster ([Fe/H]∼−1.0), and it is a well-studied representative among a number of moderately metal-poor blue horizontal branch clusters located in the bulge. The NGC 6522 abundance pattern can give hints on the earliest chemical enrichment in the central Galaxy. Aims. The aim of this study is to derive abundances of the light elements C and N; alpha elements O, Mg, Si, Ca, and Ti; odd-Z elements Na and Al; neutron-capture elements Y, Zr, Ba, La, and Nd; and the r-process element Eu. We verify if there are first- and second-generation stars:more »
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ABSTRACT Evolved Wolf–Rayet stars form a key aspect of massive star evolution, and their strong outflows determine their final fates. In this study, we calculate grids of stellar models for a wide range of initial masses at five metallicities (ranging from solar down to just 2 per cent solar). We compare a recent hydrodynamically consistent wind prescription with two earlier frequently used wind recipes in stellar evolution and population synthesis modelling, and we present the ranges of maximum final masses at core He-exhaustion for each wind prescription and metallicity Z. Our model grids reveal qualitative differences in mass-loss behaviour of the windmore »