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The $\gamma$-process in core-collapse supernovae (CCSNe) can produce a number of neutron-deficient stable isotopes heavier than iron (p-nuclei). However, current model predictions do to not fully reproduce the solar abundances. We investigate the impact of different explosion energies and parameters on the nucleosynthesis of p-nuclei, by studying stellar models with different initial masses and CCSN explosions. We find that the total p-nuclei yields are only marginally affected by the CCSN explosion prescriptions if the $\gamma$-process production is already efficient in the stellar progenitors due to a C-O shell merger. In most of CCSN explosions from progenitors without C-O shell merger, the $\gamma$-process yields increase with the explosion energy up to an order of magnitude, depending on the progenitor structure and the CCSN prescriptions. The trend of the p-nuclei production with the explosion energy is more complicated if we look at the production of single p-nuclei. The light p-nuclei tend to be the most enhanced with increasing the explosion energy. In particular, for the CCSN models where the $\alpha$-rich freeze-out component is ejected, the yields of the lightest p-nuclei increase by up to three orders of magnitude. We provide the first extensive study using different sets of massive stars of the impact of varying CCSN explosion prescriptions on the production of the p-nuclei. Unlike previous expectations and recent results in the literature, we find that the average production of p-nuclei tends to increase with the explosion energy. We also confirm that the pre-explosive production of p-nuclei in C-O shell mergers is a robust result, independently from the subsequent explosive nucleosynthesis. A realistic range of variations in the evolution of stellar progenitors and in the CCSN explosions might boost the CCSN contribution to the galactic chemical evolution of p-nuclei., Comment: 11 pages, 3 figures, 4 tables. Accepted for publication in A&A

We present an extension of the set of models published in Limongi & Chieffi, 2018, ApJS, 237, 13, at metallicity two times solar, i.e. [Fe/H]=0.3. The key physical properties of these models at the onset of the core collapse are mainly due to the higher mass loss triggered by the higher metallicity: the super solar metallicity (SSM) models reach the core collapse with smaller He- and CO-core masses, while the amount of 12C left by the central He burning is higher. These results are valid for all the rotation velocities. The yields of the neutron capture nuclei expressed per unit mass of Oxygen (i.e. the X/O) are higher in the SSM models than in the SM ones in the non rotating case while the opposite occurs in the rotating models. The trend shown by the non rotating models is the expected one, given the secondary nature of the n-capture nucleosynthesis. Vice versa, the counter intuitive trend obtained in the rotating models is the consequence of the higher mass loss present in the SSM models that removes the H rich envelope faster than in the SM ones while the stars are still in central He burning, dumping out the entanglement (activated by the rotation instabilities) and therefore a conspicuous primary n-capture nucleosynthesis., Comment: 39 pages, 6 figures, 4 tables. Accepted for publication in ApJS

Recent developments in multi-dimensional simulations of core-collapse supernovae have considerably improved our understanding of this complex phenomenon. In addition to that, one-dimensional (1D) studies have been employed to study the explosion mechanism and its causal connection to the pre-collapse structure of the star, as well as to explore the vast parameter space of supernovae. Nonetheless, many uncertainties still affect the late stages of the evolution of massive stars, their collapse, and the subsequent shock propagation. In this review, we will briefly summarize the state-of-the-art of both 1D and 3D simulations and how they can be employed to study the evolution of massive stars, supernova explosions, and shock propagation, focusing on the uncertainties that affect each of these phases. Finally, we will illustrate the typical nucleosynthesis products that emerge from the explosion., Comment: 28 pages, 12 Figures

We present the evolution and the explosion of two massive stars, 15 and 25 M$_{\odot}$, spanning a wide range of initial rotation velocities (from 0 to 800 km/s) and three initial metallicities: Z=0 ([Fe/H]=$-\infty$), $3.236\times10^{-7}$ ([Fe/H]=-5), and $3.236\times10^{-6}$ ([Fe/H]=-4). A very large nuclear network of 524 nuclear species extending up to Bi has been adopted. Our main findings may be summarized as follows: a) rotating models above Z=0 are able to produce nuclei up to the neutron closure shell at N=50, and in a few cases up to N=82; b) rotation drastically inhibits the penetration of the He convective shell in the H rich mantle, phenomenon often found in zero metallicity non rotating massive stars; c) vice versa rotation favors the penetration of the O convective shell in the C rich layers with the consequence of altering significantly the yields of the products of the C, Ne, and O burning; d) none of the models that reach the critical velocity while in H burning, loses more the 1 M$_{\odot}$ in this phase; e) conversely, almost all models able to reach their Hayashi track exceed the Eddington luminosity and lose dynamically almost all their H rich mantle. These models suggest that rotating massive stars may have contributed significantly to the synthesis of the heavy nuclei in the first phase of enrichment of the interstellar medium, i.e., at early times., Comment: 91 pages, 37 figures, 13 tables. Accepted for publication in ApJS

According to a standard initial mass function, stars in the range 7-12 Msun constitute ~50% (by number) of the stars more massive than ~7 Msun, but, in spite of this, their evolutionary properties, and in particular their final fate, are still scarcely studied. In this paper we present a detailed study of the evolutionary properties of solar metallicity, non rotating stars in the range 7-15 Msun, from the pre main sequence phase up to the presupernova stage or up to an advanced stage of the thermally pulsing phase, depending on the initial mass. We find that (1) the 7.00 Msun develops a degenerate CO core and evolves as a classical AGB star in the sense that it does not ignite the C burning reactions; (2) stars with the initial mass M >= 9.22 Msun end their life as core collapse supernovae; (3) stars in the range 7.50 <= M/Msun <= 9.20 develop a degenerate ONeMg core and evolve through the thermally pulsing SAGB phase; 4) stars in the mass range 7.50 <= M/Msun <= 8.00 end their life as hybrid CO/ONeMg- or ONeMg- WD; (5) stars with the initial mass in the range 8.50 <= M/Msun <= 9.20 may potentially explode as electron capture supernovae., Comment: 79 pages, 40 figures, 13 tables. Accepted for publication on ApJS

Using a semi-analytical model of the evolution of the Milky Way, we show how secular evolution can create distinct overdensities in the phase space of various properties (e.g. age vs metallicity or abundance ratios vs age) corresponding to the thin and thick discs. In particular, we show how key properties of the Solar vicinity can be obtained by secular evolution, with no need for external or special events, like galaxy mergers or paucity in star formation. This concerns the long established double-branch behaviour of [alpha/Fe] vs metallicity and the recently found non-monotonic evolution of the stellar abundance gradient, evaluated at the birth radii of stars. We extend the discussion to other abundance ratios and we suggest a classification scheme, based on the nature of the corresponding yields (primary vs secondary or odd elements) and on the lifetimes of their sources (short-lived vs long-lived ones). The latter property is critical in determining the single- or double- branch behavior of an elementary abundance ratio in the Solar neighborhood. We underline the high diagnostic potential of this finding, which can help to separate clearly elements with sources evolving on different timescales and help determining the site of e.g. the r-process(es). We define the "abundance distance" between the thin and thick disc sequences as an important element for such a separation. We also show how the inside-out evolution of the Milky Way disc leads rather to a single-branch behavior in other disc regions., Comment: 20 pages, 16 figures, typos corrected, matches published version in MNRAS

We present a simple criterion to predict the explodability of massive stars based on the density and entropy profiles before collapse. If a pronounced density jump is present near the Si/Si-O interface, the star will likely explode. We develop a quantitative criterion by using $\sim 1300$ 1D simulations where $\nu$-driven turbulence is included via time-dependent mixing-length theory. This criterion correctly identifies the outcome of the supernova more than $90 \%$ of the time. We also find no difference in how this criterion performs on two different sets of progenitors, evolved using two different stellar evolution codes: FRANEC and KEPLER. The explodability as a function of mass of the two sets of progenitors is very different, showing: (i) that uncertainties in the stellar evolution prescriptions influence the predictions of supernova explosions; (ii) the most important properties of the pre-collapse progenitor that influence the explodability are its density and entropy profiles. We highlight the importance that $\nu$-driven turbulence plays in the explosion by comparing our results to previous works., Comment: 20 pages, 12 figures, submitted to ApJ

Even if laboratory practice is essential for all scientific branches of knowledge, it is often neglected at High School, due to lack of time and/or resources. To establish a closer contact between school and experimental sciences, the University Sapienza of Roma and the Istituto Nazionale di Fisica Nucleare (INFN) launched the Lab2Go project, with the goal of spreading laboratory practice among students and teachers in high schools., Comment: in Italian

We discuss how the new measurement of the $^{12}C+^{12}C$ fusion cross section carried out with the Trojan Horse Method (Tumino, A., Spitaleri, C., La Cognata, M., et al., 2018, Nature 57, 687) affects the compactness of a star, i.e. basically the binding energy of the inner mantle, at the onset of the core collapse. In particular, we find that this new cross section significantly changes the dependence of the compactness on the initial mass with respect to previous findings obtained in Chieffi & Limongi 2020 (ApJ 890, 43) by adopting the classical cross section provided by Caughlan, G.R., and Fowler, W.D. 1988 (At. Data Nucl. Data Tables 40, 283). A non monotonic but well defined behavior is confirmed also in this case and no scatter of the compactness around the main trend is found. Such an occurrence could impact the possible explodability of the stars.