Understanding the origin of the elements has been a decades-long pursuit, with many open questions remaining. Old stars found in the Milky Way and its dwarf satellite galaxies can provide answers because they preserve clean element abundance patterns of the nucleosynthesis processes that operated some 13 billion years ago, enabling reconstruction of the chemical evolution of the elements. This...
Despite considerable progresses during the last decades, the origin of the elements heavier than iron is not yet fully understood. In addition to the slow (s) and rapid (r) neutron capture processes, an intermediate neutron capture process (i-process) is thought to exist at neutron densities intermediate between the s- and r-processes. The astrophysical site(s) hosting the i-process is (are)...
The most iron-poor stars are thought to be among the oldest objects observable in the sky.
Understanding them provides us a deeper knowledge on formation and evolution of the pristine universe.
In fact, they are supposed to be formed from a gas enriched just by the explosion of the first generation of massive stars.
Their chemical inventory has the signature of the nucleosynthesis both...
New rotating stellar models for the first generations of massive stars will be presented. Their results on nucleosynthesis will be compared with observed composition of very iron-poor stars and with the composition recently inferred by spectroscopy in high redshift galaxies by the JWST. We shall show that both fast-rotating Population III stars and/or non-rotating very massive stars up to...
The rapid neutron-capture process ($r$-process), known to operate in neutron-star merger (NSM) remnants, produces heavy elements whose radioactive decay deposits energy into the ejecta and powers a distinctive thermal glow called kilonova. However, an online implementation of the $r$-process in simulations is challenging due to the associated large number of isotopes in a full nuclear network....
Theory has long predicted that a dense mantle consisting of exotic nuclear structures known as “nuclear pasta” exists between the crust and the core of a neutron star. Studying this possible phase of dense matter is important since its transport and mechanical properties differ markedly from those of the crust. Different types of pasta would thus leave an imprint on many observable aspects of...
GW170817 marked the first outstanding detection of a gravitational-wave signal generated by the coalescence of a binary neutron star (BNS) system. The successful follow-up campaign carried out by electromagnetic facilities has confirmed the remarkable scientific potential of such events in the context of newborn multimessenger astrophysics. In this respect, reliable theoretical modeling of the...
The rapid neutron capture process is responsible for the synthesis of roughly half of the elements heavier than Zn ($Z>30$) in the solar system, however, it is still unclear what the exact astrophysical sites of the r-process are, and if different r-process nucleosynthetic channels exist, particularly at low metallicities. Metal-poor stars play a key role in understanding the nucleosynthesis...
Synthesis of neutron-rich isotopes is widely considered to occur via the slow neutron-capture processes (weak and main s-process). The reactions ${}^{13}\mathrm{C}(\alpha,\mathrm{n}){}^{16}\mathrm{O}$ and ${}^{22}\mathrm{Ne}(\alpha,\mathrm{n}){}^{25}\mathrm{Mg}$ are the main neutron sources for this process; the LUNA collaboration has measured the former reaction to high precision at energies...
The reaction ${}^{22}\mathrm{Ne}(\alpha,\gamma){}^{26}\mathrm{Mg}$ is associated with several questions in nuclear astrophysics, such as the Mg isotope ratio in stellar atmospheres and the nucleosynthesis of elements beyond Fe through its competition with the neutron source ${}^{22}\mathrm{Ne}(\alpha,n){}^{25}\mathrm{Mg}$.
Due to the low stellar energies and therefore very low cross...
The production of heavy elements by the rapid neutron capture process (r-process) can occur in neutron star mergers and probably in supernovae driven by strong magnetic fields. We use a complementary method to using trajectories from simulations and explore a complete and extended range of astrophysical conditions with a parametric model. This allows us to investigate all possible conditions...
$^{29}$Si is believed to be produced during classical nova events. The measurements of the isotopic ratios in primitive meteorites can represent precisely the amount of $^{29}$Si produced by such events. However, there is no unambiguous evidence for the nova paternity of presolar stardust grains. Therefore, it is important to know precisely how much $^{29}$Si is produced in classical...
Matter expelled from binary neutron star (BNS) mergers can harbor r-process nucleosynthesis and power a Kilonova (KN). Both the elemental yields and the KN transient are intimately related to the astrophysical conditions of the merger ejecta, which in turn indirectly depend on the equation of state (EOS) describing the nuclear matter inside the NS. In particular, the merger evolution is...
The light ($30 < Z < 45$) neutron-rich isotopes are thought to be synthesized in the neutrino-driven ejecta of core-collapse supernova via the weak r-process [1]. Recent nucleosynthesis studies have shown that $(\alpha,n)$ reactions play an important role in their production. The rates of these reactions have been calculated using statistical models, and their main uncertainty at the energies...
The existence of the weak intermediate neutron-capture process (i-process) explains the observed astrophysical abundances of elements around the $Z<50$ region. Neutron capture reactions in the $A=70$ mass region for Ni, Cu, and Zn isotopes are known to produce large variations in predicted i-process abundances. Predicted stellar abundances of Ga are particularly affected by the...
The amount and composition of matter ejected in core-collapse supernovae (CCSNe) are key uncertainties in models of galactic chemical evolution (GCE). Extensive grids of stellar models with varying mass and metallicity are needed. Although 3D simulations of stellar evolution and CCSNe have recently become available, the large computational cost only allows large sets of simulations under the...
Neutron capture cross sections of $^{30}$Si are an important parameter to study the origin of silicon in our Solar System and understand isotopic abundances in SiC presolar grains. The bulk of $^{30}$Si present in our Galaxy is produced in massive stars during carbon shell burning phases and its neutron capture cross sections strongly impact on its abundance. An accurate value of the neutron...
Neutron capture cross sections of $^{64}$Ni is an important parameter to accurately simulate the s-process and validate stellar models. As $^{64}$Ni is among the seeds of the s-process, the uncertainty on its capture cross section has been shown to significantly affect the predicted abundances of many isotopes produced by the s-process both in massive and AGB stars. Moreover, the uncertain...
Accelerator Mass Spectrometry (AMS) is the most sensitive technique for direct atom counting of many long-lived radionuclides. The addition of a buffer gas-filled ion cooler to the low-energy side of the AMS system opens up exciting new possibilities, especially in the mass range $60-200\,\mathrm{amu}$. The new ion cooler ILTIS, built at Helmholtz-Zentrum Dresden-Rossendorf in cooperation with...
There are three “families” of nuclides with a particular value for s-process studies: s-only nuclei, bottlenecks and branchings. Interestingly, for none of them is the situation satisfactory from an experimental standpoint.
This contribution summarizes selected examples utilizing the time-of-flight technique at CERN n_TOF in combination with detection systems, which have been progressively...
More than 50 years after the discovery of neutrons stars, their interior composition and structure remain unknown. Because the extreme densities and matter asymmetry in neutron star interiors are out of reach for Earth laboratories, the equation of state of bulk nuclear matter is unknown, and its determination would have implication for astrophysics and nuclear physics. Thankfully,...
Active nucleosynthesis in our galaxy can be observed directly through the detection of long-lived radioactivities. Isotopes such as $^{26}$Al, and $^{60}$Fe have been observed either in solar system samples or through $\gamma$-ray observations within the galaxy. Both isotopes are predominantly produced in massive stars and ejected into the interstellar medium either via stellar winds or...
Lead-205 looks like a promising cosmochronometer for the early Solar System due to its unique position among astrophysically short-lived radionuclides as an s-only isotope probing the termination of the s process [1]. Unfortunately, the 2.3 keV first excited state in $^{205}$Pb reduces the half-life in stellar environments by around 6 orders of magnitude, which could severely inhibit...
$^{205}$Pb has been proposed as a cosmochronometer for the early solar system as it is only produced in the s-process and has a half-life of 17 My. This half-life can change dramatically in the stellar environment depending on the ionization stage of $^{205}$Pb and $^{205}$Tl and the thermal population of excited nuclear states. $^{205}$Pb has an excited 1/2$^-$ state at 2.3 keV that shortens...
Gravitational wave asteroseismology is a promising approach for studying neutron stars' characteristics and constraining dense matter equation of state (EoS). Several quasi-universal empirical relations have been developed to link the frequencies of normal modes to various stellar properties such as mass and radius. These relations allow us to extract macroscopic information about the stars...
Majority of the heavy chemical elements are formed via neutron capture reactions. However, there are a few proton rich nuclei (p-isotopes) which cannot be created these ways.In a high temperature environment pre-existing nuclei can photodissociate, and through $(\gamma,\mathrm{n})$ reactions the p-isotopes can be created. Subsequent $(\gamma,\mathrm{n})$ reactions increase the neutron...
Among the different signals in multimessenger astrophysics, the kilonovae are of particular interest to nuclear physicists. These electromagnetic signals can emerge from the ejecta of neutron star (NS) - NS mergers [1]. They are expected to be powered by nuclear decays since such mergers are considered dominant sites for r-process nucleosynthesis of heavy (unstable) nuclei. Even though there...
Theoretical models aiming to accurately reproduce observed nuclear abundances require complex calculations utilizing nuclear reaction networks. These networks encompass the nature of nuclear reactions and decays, accounting for both the production and destruction of nuclei. The explosive conditions in r-process sites, where temperatures rise to the order of Giga Kelvin, may lead to nuclei...
Stars of different properties produce different elements. For instance, rotating massive stars are supposed to produce trans-iron elements at low metallicities (e.g. Frischknecht et al. 2012, Limongi & Chieffi 2018). Also, in low-mass galaxies, astrophysical events can appear sporadically. Thus, the relative contribution of astrophysical events to the chemical enrichment may not be compared to...
The fate of stars with intermediate mass ($\approx 7-11 \, M_\odot$) is still not certain. In their final stages, they develop degenerate oxygen-neon cores, potentially culminating in electron capture supernovae. Both a thermonuclear explosion, as well as a collapse to a neutron star are possible, critically depending on the oxygen ignition density. Understanding the oxygen ignition process is...
The ${}^3\mathrm{He}(\alpha,\gamma){}^7\mathrm{Be}$ reaction plays a major role both in the big bang nucleosynthesis (BBN) where it affects the primordial $^7$Li production, and in the solar energy generation via the pp-chain where as a branching point it affects the flux of neutrinos. Precise understanding of the reaction mechanism is of crucial importance for BBN and solar model...
The neutron-rich $N\sim126$ region is important to r-process calculations and has been less explored by experiments. This region is unique for its strong competition between allowed and first-forbidden transitions [1], which complicates half-life predictions. Besides, the position of the third r-process abundance peak and production of actinides are sensitive to half-lives of $N=126$ isotones...
Superluminous supernovae are a class of exceedingly bright transients whose luminosity cannot be comfortably explained by the standard 56Ni-decay picture. The quest for an alternative scenario has pointed at the contribution of a nascent millisecond magnetar and/or at the interaction of the supernova ejecta with a circumstellar medium surrounding the progenitor star; however, some of the...
Nuclear fission is one of the most important nuclear phenomena and arguably its most interesting astrophysical application is in the study of r-process nucleosynthesis. The theoretical description of fission is a challenging quantum many body problem and one such key challenge is the description of collective inertias along the fission path. In most of the fission calculations, the collective...
Solar neutrinos play a significant role in constraining physical conditions in the interior of the Sun and are a unique tool to investigate its core composition. The ${}^{14}\mathrm{N}(p,\gamma){}^{15}\mathrm{O}$ cross section is the dominant error source on neutrino flux predictions. At solar energies ($15 - 50\,\mathrm{keV}$) such a cross-section is too low to be measured directly, therefore...
The Bellotti Ion Beam Facility was inaugurated in 2023. It currently houses a 3.5 MV Singletron accelerator supplied by High Voltage Engineering Europe, installed inside the deep underground Laboratori Nazionali del Gran Sasso (LNGS) in Italy, where the natural cosmic ray flux is reduced by up to six orders of magnitude. The installation of the facility has been supported by the "LUNA-MV...
Charge-Exchange (CE) reactions are an important tool for studying the spin-isopin response of nuclei. They can be utilized to obtain information about interactions mediated by the weak nuclear force, such as $\beta$ and electron capture decay. Using the proportionality between Gamow-Teller strength (B(GT)) and the CE differential cross section, B(GT) distributions can be extracted indirectly....
The most massive stars provide an essential source of recycled material for young clusters and galaxies. While very massive stars (VMS, $M>100 \,M_\odot$) are relatively rare compared to O stars, they lose disproportionately large amounts of mass already from the onset of core H-burning. In this talk, I will discuss the impact of stellar wind yields from VMS, calculated for a wide range of...
The chemical compositions of stars place key constraints on nuclear astrophysics. The most precise way of determining these compositions is through analyses of the absorption lines in the observed star light (stellar spectroscopy). However, the accuracy of standard analyses of Sun-like stars can be limited by various simplifying assumptions. The vast majority of analyses take the atmosphere...
During the last 30 years, the Laboratory for Underground Nuclear Astrophysics (LUNA) investigated many nuclear reactions of interest for cosmological and stellar models, often directly at the relevant Astrophysical energies. Nuclear reactions involved in the Big Bang nucleosynthesis, the p-p and CNO chains, as well as slow neutron capture were studied providing accurate and precise data to the...
The NeNa-MgAl cycles are involved in the synthesis of Ne, Na, Mg, and Al isotopes. The ${}^{20}\mathrm{Ne}(p,\gamma){}^{21}\mathrm{Na}$ reaction is the slowest reaction of the NeNa cycle and it controls the speed at which the entire cycle proceeds. The ${}^{21}\mathrm{Ne}(p,\gamma){}^{22}\mathrm{Na}$ has a relevant role in the production of the radioactive isotope ${}^{22}\mathrm{Na}$ that is...
We obtain posterior distribution of equations of state (EOSs) across a broad range of density by imposing explicitly the constraints from precisely measured fundamental properties of finite nuclei, in combination with experimental data from heavy-ion collisions and astrophysical observations of radius, tidal deformability and minimum-maximum mass of neutron stars. The acquired EOSs exhibit a...
Elemental abundances are excellent probes of classical novae (CN). Sensitivity studies show that $^{38}$K($p$,$\gamma$)$^{39}$Ca reaction-rate uncertainties modify the abundance of calcium by a factor of 60 in CN ejecta. Existing direct and indirect measurements are in contradiction concerning the energies and strengths of important resonances in the $^{38}$K($p$,$\gamma$)$^{39}$Ca reaction....
The spontaneously fissioning isotope californium-254 is predicted to have a high impact on the brightness of electromagnetic transients associated with neutron star mergers on the timescale of 10 to 250 days, due to its 60-day half-life. [Zhu et al., AJL 863, L23 (2018)]. Experimental information on Cf-254 is scarce, owing to limited production capabilities in the laboratory. We have performed...
In recent years, new experimental determinations of nuclear reaction rates relevant to astrophysics have been obtained using experimental (direct and indirect) and theoretical methods, highlighting specific trends such as the unexpected fusion hindrance phenomenon for ions or multiple resonances. Especially, a precise determination of the nuclear reaction rates is a crucial ingredient in...
Given the key role massive stars and core-collapse supernovae play in the Universe, developing theoretical models of massive stars and their final collapse is critical. Massive stars are complex 3D objects involving a wide range of interesting physical processes like convection. Stellar models would thus ideally be three-dimensional (3D) (magneto-)hydrodynamic models that include all the...
The rapid neutron capture process (r-process) is a key mechanism responsible for producing nearly half of the nuclei heavier than iron in explosive scenarios. In the solar-system abundance pattern, the Rare-Earth Peak (REP) around mass number $A = 160$ represents a significant feature resulting from freeze-out during the final stages of neutron exposure. The BRIKEN collaboration [1] conducted...
Massive stars are not well enough understood given the important role their evolution and fates play in Galactic Chemical Evolution (GCE). One key uncertainty is convective boundary mixing (CBM), which encompasses the processes by which materials mix across the edge of convective turbulent regions inside stars. As a result of its effects on stellar structure during evolution, CBM also affects...
An white dwarf (WD) which accreates enough mass to surpass the Chandrasekhar limit will became unstable and will initiate a collapse stage due to its own gravity. Depending on their composition and their accretion history, the collapsing WD may trigger a thermonuclear explosion (and lead to a Supernova Ia) or not. In the latter case, the collapse, completely driven by the electron capture...
The nucleosynthetic s-process occurring in AGB stars from 1-6 M is responsible for creating half of the heavy elements in the universe. The s-process can be traced directly through AGB stars, or indirectly through their binary companions (Ba, CEMP-s, CH stars), as AGBs will dredge s-process material to the surface and deposit this material onto the companion.
We present data for 30 stars...
With the detection of multiple neutron-star merger events in the last few years, the need for a more comprehensive understanding of nuclear and atomic properties has become increasingly important. Despite our current understanding, there are still large discrepancies in the opacities obtained from different codes and methods. These discrepancies lead to variations in the location and strength...
Accelerator mass spectrometry (AMS) is commonly the most sensitive technique for detection of long-lived isotopes and has allowed identification of $^{60}$Fe and $^{244}$Pu signals in terrestrial and lunar archives from recent nearby nucleosynthesis.
Belonging to the middle-mass region of r-process nuclides, $^{182}$Hf (T$_{1/2}$=8.9$\,$Ma) could potentially be produced in different scenarios...
The existence of some stable neutron deficient nuclei - the p nuclei - can not be explained by neutron-capture processes [1]. Therefore, other types of reactions - dominantly photodisintegration reactions - come into play. This is called the $\gamma$ process. Statistical model calculations play a crucial role in modelling this process as cross sections for many of these photodisintegration...
The K-Pg (Cretaceous–Paleogene) boundary at 66 Ma marks one of five major mass extinctions in Earth’s fossil history. Based on strong enrichments of platinum-group elements, Alvarez et al. [1], in 1980, suggested that the impact of a large asteroid was responsible for the K/Pg event. To exclude other causes for the mass extinction, e.g., a nearby supernova(SN)-explosion, they also searched for...
The determination of the equation of state (EoS) of dense matter is a challenge in nuclear astrophysics, and particularly for the modelling of compact obects such as supernovae and neutron stars (NSs). Indeed, a consistent description of the different states of matter encountered in these stellar objects spanning a wide range of densities, temperatures, and isospin asymmetries is a difficult...
The gamma-ray decay of nuclear states in the quasi-continuum provides significant constraints on nucleosynthesis processes. In particular, measurements of Nuclear Level Densities (NLDs) and Photon Strength Functions (PSFs) have and will continue to play a central role as these are inputs for the statistical Hauser-Feshbach model. This facilitates the extraction of neutron-capture cross-section...
Over the past decades nuclear physicists have been trying to measure the rates of the most relevant nuclear reactions, which are responsible for the element nucleosynthesis, but there is still considerable uncertainty about their values.
This is because their reaction rates are extremely small, making it difficult for them to be measured directly in the laboratory. Indeed, although e.g. the...
We study the impact of asymmetric fermionic and bosonic dark matter on neutron star properties, including tidal deformability, maximum masses, radii, thermal evolution, a moment of inertia, quasi-universal relations, etc. The conditions at which dark matter particles tend to condense in the core of the star or create an extended halo are presented. We show that dark matter condensed in a core...
The nuclear symmetry energy and its density dependence play a crucial role in defining the properties of a wide range of systems, spanning from asymmetric nuclei to neutron stars and various other astrophysical phenomena. Motivated by recent advancements, particularly the precise determination of neutron skin thickness for ${}^{208}\mathrm{Pb}$ and ${}^{48}\mathrm{Ca}$ nuclei through PREX-II...
The $^{17}$O(p,$\gamma$)$^{18}$F reaction plays a key role in the hydrogen burning in CNO cycle. At temperatures of interest for the H-shell burning in AGB stars, the reaction rate is dominated by the $E_\mathrm{c.m.}=65\,\mathrm{keV}$ resonance.
The strength of this resonance is presently determined only through indirect techniques, with a literature value $\omega\gamma = (16 \pm...
Carbon burning is the third stage of stellar evolution determining the final destiny of massive stars and of low-mass stars in close binary systems. Only stars with a mass larger than a critical value $M^{*}_{up}\sim10M_\odot$, can ignite C in non-degenerate conditions and proceed to the next advanced burning stages up to the formation of a gravitationally unstable iron core. Various final...
We have developed a new, extremely precise experimental approach for measuring the lifetimes of excited states. This method uses gamma-tracking detectors with high resolution in energy and angle.
This method has been used at GANIL, France, to measure the lifetimes of 23Mg excited states. The gamma rays were measured with the AGATA gamma-ray detector, and the ejectiles from the...
Nuclear astrophysics is a field of research that lends itself to an engaging dissemination thanks to its interdisciplinary nature. It is important to involve blind or deaf individuals in these moments of dissemination to an even greater extent. The project ‘Stelle sulla Terra’ at the University of Padua aims to achieve this by reproducing a scaled model of the ‘Bellotti’ IBF facility and...
The electromagnetic signals from the kilonova AT2017gfo provide an opportunity to study an astrophysical site of the r-process which produced about half of all nuclei heavier than iron. In order to be able to connect kilonova light curve and spectral properties to the ejecta dynamics it is important to address the role of the individual simplifying assumptions commonly used in theoretical...
A small fraction of old, metal-poor stars exhibits significant enhancement in elements produced through the rapid neutron capture (r-) process, offering a unique laboratory to investigate this process. The R-Process Alliance's initial data release uncovered numerous highly r-processed (r-II) stars. In my work I delve into a detailed chemical analysis of ten such stars, utilizing high-quality...
The radioisotope ${}^{26}\mathrm{Al}$ plays a crucial role in understanding the origins of cosmic elements, particularly at active nucleosynthesis sites such as supernovae and massive star-forming regions. Its characteristic $1809\,\mathrm{keV}$ $\gamma$-ray emission, observed by gamma telescopes, serves as direct evidence of ongoing nucleosynthesis processes. Neutron-induced reactions,...
We study the properties of hybrid stars containing a color superconducting quark matter phase in their cores, described by the chirally symmetric formulation of the confining relativistic density functional approach. It is shown that depending on the dimensionless vector and diquark couplings of quark matter, the characteristics of the deconfinement phase transition are varied, allowing us to...
The astrophysical site of the r-process remains an open question in nuclear astrophysics. Pure r-process radionuclides present in the solar system today that cannot originate from primordial events due to their comparably short half-lives (e.g. $^{\textrm{244}}$Pu t$_{1/2}\,\sim\,$81$\,$Myr) act as fingerprints of recent r-process events in the solar neighbourhood. The discovery of live...
Direct evidence of the r-process has recently been observed in neutron star mergers, but the debate on the Nucleosynthesis environment is still far from over. Due to the scarcity of experimental information, modern r-process network calculations rely on theoretical models that give divergent predictions as one moves away from the valley of stability. Nuclear masses help to determine the...
The lowest metallicity stars in the Milky Way Halo are the fossil records of the earliest star-forming environments in the universe. Their chemical abundance patterns help us understand primordial nucleosynthesis, the mass function of the first stars, and the pathways that led to the chemical complexity we observe today. However, there is still debate about when (and for how long) the universe...
The amount of carbon and oxygen generated during the helium burning phase of stars has profound implications for stellar evolution. A primary source of this uncertainty lies in the $^{12}\mathrm{C}(\alpha,\gamma)^{16}\mathrm{O}$ reaction, which has been under investigation for over six decades. Despite persistent efforts, the uncertainty regarding the astrophysical factor remains above 10%,...
The presence of long-lived radionuclides provides insights into the solar system's history. The radionuclide $^{60}$Fe (t$_{1/2}\,$=$\,$2.6$\,$Myr) is mainly synthesized in massive stars and subsequently ejected by supernovae. Embedded into dust grains, $^{60}$Fe can enter the solar system and be deposited into terrestrial archives, where it evidences stellar explosions even after several...
Almost all nuclei heavier than iron are produced through neutron capture nucleosynthesis, about half of them by the rapid (r) process. One of the limiting factors in understanding the r-process is the need for neutron capture cross-section measurements on unstable nuclei. As shown with the recent measurement of $^{88}$Zr (Shusterman et al., Nature 2019), neutron capture cross-sections can...
We investigate the nucleosynthesis and kilonova light curve based on recent long-term binary neutron star merger simulations that incorporate a two-moment neutrino-transport scheme. The ejecta are evolved for 30 days using axisymmetric radiation-hydrodynamics simulations coupled in-situ to a complete nuclear network. For the first time, we find that the neutrino-driven wind from the...
Heavy element nucleosynthesis is largely governed by $n$-capture processes. However, a group of neutron-deficient isotopes, the $p$ nuclei, cannot be formed by any of those processes. These $\sim30$ nuclei are believed to be formed in the $\gamma$ process through a sequence of photodisintegration reactions on preexisting $r$- and $s$-process seeds. Reproducing the solar $p$-nuclei abundances...
At the end of its evolution, the collapse of a massive star's core into a proto-neutron star is the starting point for a complex sequence of events with many possible outcomes.
Specifically, very compact and rotating stars with a high mass ($M_*>16 \,M_\odot$), are likely to create a so-called ``failed core-collapse supernova'', forming a black hole surrounded by an accreting disk. It has...
The amount of carbon and oxygen generated during the helium burning phase of stars has profound implications for stellar evolution. A primary source of this uncertainty lies in the $^{12}\mathrm{C}(\alpha,\gamma)^{16}\mathrm{O}$ reaction, which has been under investigation for over six decades. Despite persistent efforts, the uncertainty regarding the astrophysical factor remains above 10%,...
Given the key role massive stars and core-collapse supernovae play in the Universe, developing theoretical models of massive stars and their final collapse is critical. Massive stars are complex 3D objects involving a wide range of interesting physical processes like convection. Stellar models would thus ideally be three-dimensional (3D) (magneto-)hydrodynamic models that include all the...
We present a new grid of 3D non-LTE -- 1D LTE Barium abundance corrections developed in the framework of the EU-funded ChETEC-INFRA project. The grid covers dwarfs, subgiant, and giant stars of spectral type F, G, K from solar to metal-poor metalicities for five commonly used Ba II lines. Based on a total of about 100 CO5BOLD 3D hydrodynamical stellar atmosphere models and associated 1D MARCS...
GW170817 marked the first outstanding detection of a gravitational-wave signal generated by the coalescence of a binary neutron star (BNS) system. The successful follow-up campaign carried out by electromagnetic facilities has confirmed the remarkable scientific potential of such events in the context of newborn multimessenger astrophysics. In this respect, reliable theoretical modeling of the...
Majority of the heavy chemical elements are formed via neutron capture reactions. However, there are a few proton rich nuclei (p-isotopes) which cannot be created these ways.In a high temperature environment pre-existing nuclei can photodissociate, and through $(\gamma,\mathrm{n})$ reactions the p-isotopes can be created. Subsequent $(\gamma,\mathrm{n})$ reactions increase the neutron...
The opacity of plasma is often utilized in astrophysics for studying solar models, (solar) neutrino observations or neutron star mergers. The opacity of an atomic ion hereby quantifies how photons are absorbed or re-scattered by the plasma ions. The opacity of different ion sources also enters explicitly the radiation transport in different environments, such as stellar interiors, fusion...
Gravitational wave asteroseismology is a promising approach for studying neutron stars' characteristics and constraining dense matter equation of state (EoS). Several quasi-universal empirical relations have been developed to link the frequencies of normal modes to various stellar properties such as mass and radius. These relations allow us to extract macroscopic information about the stars...
The rapid neutron capture process is responsible for the synthesis of roughly half of the elements heavier than Zn ($Z>30$) in the solar system, however, it is still unclear what the exact astrophysical sites of the r-process are, and if different r-process nucleosynthetic channels exist, particularly at low metallicities. Metal-poor stars play a key role in understanding the nucleosynthesis...
We present a newly developed jet and extended windowless gas target system, tailored to meet the precision measurement demands of modern nuclear astrophysics. Our system can be operated either in jet or extended modes without necessitating modifications in pumping power. Real-time monitoring of a jet, facilitated by laser interferometry techniques, ensures control of target parameters during...
The electromagnetic signals from the kilonova AT2017gfo provide an opportunity to study an astrophysical site of the r-process which produced about half of all nuclei heavier than iron. In order to be able to connect kilonova light curve and spectral properties to the ejecta dynamics it is important to address the role of the individual simplifying assumptions commonly used in theoretical...
The production of heavy elements by the rapid neutron capture process (r-process) can occur in neutron star mergers and probably in supernovae driven by strong magnetic fields. We use a complementary method to using trajectories from simulations and explore a complete and extended range of astrophysical conditions with a parametric model. This allows us to investigate all possible conditions...
The existence of the weak intermediate neutron-capture process (i-process) explains the observed astrophysical abundances of elements around the $Z<50$ region. Neutron capture reactions in the $A=70$ mass region for Ni, Cu, and Zn isotopes are known to produce large variations in predicted i-process abundances. Predicted stellar abundances of Ga are particularly affected by the...
Heavy element nucleosynthesis is largely governed by $n$-capture processes. However, a group of neutron-deficient isotopes, the $p$ nuclei, cannot be formed by any of those processes. These $\sim30$ nuclei are believed to be formed in the $\gamma$ process through a sequence of photodisintegration reactions on preexisting $r$- and $s$-process seeds. Reproducing the solar $p$-nuclei abundances...
Type-I X-ray bursts are thermonuclear explosions in the atmospheres of accreting neutron stars in close binary systems. During these bursts, temperatures are achieved ($0.8-1.5\,\mathrm{GK}$) such that breakout from the HCNO cycle occurs, resulting in a whole new set of thermonuclear reactions; the rp-process.
Sensitivity studies have highlighted the...
Stars of different properties produce different elements. For instance, rotating massive stars are supposed to produce trans-iron elements at low metallicities (e.g. Frischknecht et al. 2012, Limongi & Chieffi 2018). Also, in low-mass galaxies, astrophysical events can appear sporadically. Thus, the relative contribution of astrophysical events to the chemical enrichment may not be compared to...
The amount and composition of matter ejected in core-collapse supernovae (CCSNe) are key uncertainties in models of galactic chemical evolution (GCE). Extensive grids of stellar models with varying mass and metallicity are needed. Although 3D simulations of stellar evolution and CCSNe have recently become available, the large computational cost only allows large sets of simulations under the...
The astrophysical site of the r-process remains an open question in nuclear astrophysics. Pure r-process radionuclides present in the solar system today that cannot originate from primordial events due to their comparably short half-lives (e.g. $^{\textrm{244}}$Pu t$_{1/2}\,\sim\,$81$\,$Myr) act as fingerprints of recent r-process events in the solar neighbourhood. The discovery of live...
Charge-Exchange (CE) reactions are an important tool for studying the spin-isopin response of nuclei. They can be utilized to obtain information about interactions mediated by the weak nuclear force, such as $\beta$ and electron capture decay. Using the proportionality between Gamow-Teller strength (B(GT)) and the CE differential cross section, B(GT) distributions can be extracted indirectly....
The relative variations of the chemical compositions between metal-poor stars ($[\mathrm{F}/\mathrm{H}] < -1$) give the possibility to reveal the pure signature of unique nucleosynthesis processes. The study of the r-process is for instance one of the main goals of stellar archaeology.
In this work we present the atmospheric parameter, the main dynamic properties and the abundances of four...
The E1 $\gamma$-ray strengh of the Pygmy Dipole Resonance (PDR), close to the neutron threshold on the top of the low-energy tail of the Isovector Giant Dipole Resonance (IVGDR), exhausting only few percent of the TRK sum rule is known to affect significantly the radiative neutron capture cross section calculations of the astrophysical r-process [1] which is responsible for the...
We present a relativistic density functional approach to color superconducting quark matter that mimics quark confinement by a fast growth of the quasiparticle self-energy in the confining region. The approach is shown to be equivalent to a chiral model of quark matter with medium dependent couplings. The approach to the conformal limit at asymptotically high densities is provided by a medium...
The rapid neutron-capture process ($r$-process), known to operate in neutron-star merger (NSM) remnants, produces heavy elements whose radioactive decay deposits energy into the ejecta and powers a distinctive thermal glow called kilonova. However, an online implementation of the $r$-process in simulations is challenging due to the associated large number of isotopes in a full nuclear network....
The ${}^3\mathrm{He}(\alpha,\gamma){}^7\mathrm{Be}$ reaction plays a major role both in the big bang nucleosynthesis (BBN) where it affects the primordial $^7$Li production, and in the solar energy generation via the pp-chain where as a branching point it affects the flux of neutrinos. Precise understanding of the reaction mechanism is of crucial importance for BBN and solar model...
The spontaneously fissioning isotope californium-254 is predicted to have a high impact on the brightness of electromagnetic transients associated with neutron star mergers on the timescale of 10 to 250 days, due to its 60-day half-life. [Zhu et al., AJL 863, L23 (2018)]. Experimental information on Cf-254 is scarce, owing to limited production capabilities in the laboratory. We have performed...
$^{29}$Si is believed to be produced during classical nova events. The measurements of the isotopic ratios in primitive meteorites can represent precisely the amount of $^{29}$Si produced by such events. However, there is no unambiguous evidence for the nova paternity of presolar stardust grains. Therefore, it is important to know precisely how much $^{29}$Si is produced in classical...
The neutron time-of-flight facility nELBE at Helmholtz-Zentrum Dresden-Rossendorf features the first photo-neutron source at a superconducting electron accelerator. The electrons are focused onto a liquid-lead target to produce bremsstrahlung which in turn produces neutrons via photo-nuclear reactions. The emitted neutron spectrum ranges from about 10 keV up to 15 MeV with a source strength of...
In recent years, new experimental determinations of nuclear reaction rates relevant to astrophysics have been obtained using experimental (direct and indirect) and theoretical methods, highlighting specific trends such as the unexpected fusion hindrance phenomenon for ions or multiple resonances. Especially, a precise determination of the nuclear reaction rates is a crucial ingredient in...
Barium (Ba) stars belong to binary systems where a former asymptotic giant branch (AGB, now a white dwarf) star polluted the less evolved companion, which became enriched with material produced through the slow neutron capture process (s process). The currently observed Ba star preserves the abundance pattern of the AGB, allowing us to test the imprints of the s process. Comparing different...
The detection of cosmic signatures in deep-sea, ice, and lunar samples has made an important contribution to nuclear astrophysics in recent years. In particular, ${}^{60}$Fe from near-Earth supernovae has been imprinted during the time periods $2-3$ and $7-8\,\mathrm{Myr}$ ago.
This data corroborates theoretical studies that suggest that more than $10$ SNe exploded at a distance of...
Alpha-induced reactions at thermonuclear energies are difficult to measure directly, if the cross section is too low, or highly enriched isotopic material is required as target material. Transmission of fast neutrons in the MeV range can be used to find resonances that would be difficult to study in the direct reaction. In this way, the reaction ${}^{17}\mathrm{O}(\alpha,n){}^{20}\mathrm{Ne}$...
The $^{17}$O(p,$\gamma$)$^{18}$F reaction plays a key role in the hydrogen burning in CNO cycle. At temperatures of interest for the H-shell burning in AGB stars, the reaction rate is dominated by the $E_\mathrm{c.m.}=65\,\mathrm{keV}$ resonance.
The strength of this resonance is presently determined only through indirect techniques, with a literature value $\omega\gamma = (16 \pm...
With the detection of multiple neutron-star merger events in the last few years, the need for a more comprehensive understanding of nuclear and atomic properties has become increasingly important. Despite our current understanding, there are still large discrepancies in the opacities obtained from different codes and methods. These discrepancies lead to variations in the location and strength...
The neutron-rich $N\sim126$ region is important to r-process calculations and has been less explored by experiments. This region is unique for its strong competition between allowed and first-forbidden transitions [1], which complicates half-life predictions. Besides, the position of the third r-process abundance peak and production of actinides are sensitive to half-lives of $N=126$ isotones...
A small fraction of old, metal-poor stars exhibits significant enhancement in elements produced through the rapid neutron capture (r-) process, offering a unique laboratory to investigate this process. The R-Process Alliance's initial data release uncovered numerous highly r-processed (r-II) stars. In my work I delve into a detailed chemical analysis of ten such stars, utilizing high-quality...
We investigate the nucleosynthesis and kilonova light curve based on recent long-term binary neutron star merger simulations that incorporate a two-moment neutrino-transport scheme. The ejecta are evolved for 30 days using axisymmetric radiation-hydrodynamics simulations coupled in-situ to a complete nuclear network. For the first time, we find that the neutrino-driven wind from the...
Theoretical models aiming to accurately reproduce observed nuclear abundances require complex calculations utilizing nuclear reaction networks. These networks encompass the nature of nuclear reactions and decays, accounting for both the production and destruction of nuclei. The explosive conditions in r-process sites, where temperatures rise to the order of Giga Kelvin, may lead to nuclei...
Massive stars are not well enough understood given the important role their evolution and fates play in Galactic Chemical Evolution (GCE). One key uncertainty is convective boundary mixing (CBM), which encompasses the processes by which materials mix across the edge of convective turbulent regions inside stars. As a result of its effects on stellar structure during evolution, CBM also affects...
The CNO cycle plays a key role in the nucleosynthesis of massive stars and their energy production. The $^{14}\mathrm{N}(\mathrm{p},\gamma){}^{15}\mathrm{O}$ reaction is the slowest in this cycle and, therefore, controls the speed of the entire cycle, influencing the synthesis of carbon, nitrogen, oxygen and fluorine. However, investigating the reaction at astrophysically relevant energies is...
Among the different signals in multimessenger astrophysics, the kilonovae are of particular interest to nuclear physicists. These electromagnetic signals can emerge from the ejecta of neutron star (NS) - NS mergers [1]. They are expected to be powered by nuclear decays since such mergers are considered dominant sites for r-process nucleosynthesis of heavy (unstable) nuclei. Even though there...
The light ($30 < Z < 45$) neutron-rich isotopes are thought to be synthesized in the neutrino-driven ejecta of core-collapse supernova via the weak r-process [1]. Recent nucleosynthesis studies have shown that $(\alpha,n)$ reactions play an important role in their production. The rates of these reactions have been calculated using statistical models, and their main uncertainty at the energies...
Direct evidence of the r-process has recently been observed in neutron star mergers, but the debate on the Nucleosynthesis environment is still far from over. Due to the scarcity of experimental information, modern r-process network calculations rely on theoretical models that give divergent predictions as one moves away from the valley of stability. Nuclear masses help to determine the...
The radioisotope ${}^{26}\mathrm{Al}$ plays a crucial role in understanding the origins of cosmic elements, particularly at active nucleosynthesis sites such as supernovae and massive star-forming regions. Its characteristic $1809\,\mathrm{keV}$ $\gamma$-ray emission, observed by gamma telescopes, serves as direct evidence of ongoing nucleosynthesis processes. Neutron-induced reactions,...
Neutron capture cross sections of $^{30}$Si are an important parameter to study the origin of silicon in our Solar System and understand isotopic abundances in SiC presolar grains. The bulk of $^{30}$Si present in our Galaxy is produced in massive stars during carbon shell burning phases and its neutron capture cross sections strongly impact on its abundance. An accurate value of the neutron...
Neutron capture cross sections of $^{64}$Ni is an important parameter to accurately simulate the s-process and validate stellar models. As $^{64}$Ni is among the seeds of the s-process, the uncertainty on its capture cross section has been shown to significantly affect the predicted abundances of many isotopes produced by the s-process both in massive and AGB stars. Moreover, the uncertain...
The $^{3}$He($\alpha,\gamma$)$^{7}$Be reaction plays a significant role in Big Bang nucleosynthesis, as well as in stellar hydrogen burning. It affects the nucleosynthesis of primordial $^{7}$Li, as well as the theoretical prediction of solar $^{7}$Be and $^{8}$B neutrino fluxes.
A measurement of its $\gamma$-ray angular distribution was performed using the 5$\,$MV Pelletron accelerator at...
Nuclear fission is one of the most important nuclear phenomena and arguably its most interesting astrophysical application is in the study of r-process nucleosynthesis. The theoretical description of fission is a challenging quantum many body problem and one such key challenge is the description of collective inertias along the fission path. In most of the fission calculations, the collective...
An white dwarf (WD) which accreates enough mass to surpass the Chandrasekhar limit will became unstable and will initiate a collapse stage due to its own gravity. Depending on their composition and their accretion history, the collapsing WD may trigger a thermonuclear explosion (and lead to a Supernova Ia) or not. In the latter case, the collapse, completely driven by the electron capture...
The lowest metallicity stars in the Milky Way Halo are the fossil records of the earliest star-forming environments in the universe. Their chemical abundance patterns help us understand primordial nucleosynthesis, the mass function of the first stars, and the pathways that led to the chemical complexity we observe today. However, there is still debate about when (and for how long) the universe...
The rapid neutron capture process (r-process) is a key mechanism responsible for producing nearly half of the nuclei heavier than iron in explosive scenarios. In the solar-system abundance pattern, the Rare-Earth Peak (REP) around mass number $A = 160$ represents a significant feature resulting from freeze-out during the final stages of neutron exposure. The BRIKEN collaboration [1] conducted...
Almost all nuclei heavier than iron are produced through neutron capture nucleosynthesis, about half of them by the rapid (r) process. One of the limiting factors in understanding the r-process is the need for neutron capture cross-section measurements on unstable nuclei. As shown with the recent measurement of $^{88}$Zr (Shusterman et al., Nature 2019), neutron capture cross-sections can...
Theory has long predicted that a dense mantle consisting of exotic nuclear structures known as “nuclear pasta” exists between the crust and the core of a neutron star. Studying this possible phase of dense matter is important since its transport and mechanical properties differ markedly from those of the crust. Different types of pasta would thus leave an imprint on many observable aspects of...
Photon-induced reactions are interesting tools for nuclear-structure and nuclear-astrophysics experiments. In particular, the photon-scattering or nuclear-resonance-fluorescence method can gain unique information about nuclear excitations with low spin. Excitations close to the neutron-separation energy attract growing interest because they may reveal information about new excitation modes and...
Matter expelled from binary neutron star (BNS) mergers can harbor r-process nucleosynthesis and power a Kilonova (KN). Both the elemental yields and the KN transient are intimately related to the astrophysical conditions of the merger ejecta, which in turn indirectly depend on the equation of state (EOS) describing the nuclear matter inside the NS. In particular, the merger evolution is...
We study the properties of hybrid stars containing a color superconducting quark matter phase in their cores, described by the chirally symmetric formulation of the confining relativistic density functional approach. It is shown that depending on the dimensionless vector and diquark couplings of quark matter, the characteristics of the deconfinement phase transition are varied, allowing us to...
Role of short-range correlations (SRCs) on properties of the neutron stars is re-examined by considering the behaviour of low density part of the equation of state, such that bulk properties of finite nuclei such that binding energy, charge radius, iso-scalar giant monopole resonance etc. remains unaffected with the addition of SRCs, within the framework of relativistic mean-field (RMF)...
Lead-205 looks like a promising cosmochronometer for the early Solar System due to its unique position among astrophysically short-lived radionuclides as an s-only isotope probing the termination of the s process [1]. Unfortunately, the 2.3 keV first excited state in $^{205}$Pb reduces the half-life in stellar environments by around 6 orders of magnitude, which could severely inhibit...
Elemental abundances are excellent probes of classical novae (CN). Sensitivity studies show that $^{38}$K($p$,$\gamma$)$^{39}$Ca reaction-rate uncertainties modify the abundance of calcium by a factor of 60 in CN ejecta. Existing direct and indirect measurements are in contradiction concerning the energies and strengths of important resonances in the $^{38}$K($p$,$\gamma$)$^{39}$Ca reaction....
The existence of some stable neutron deficient nuclei - the p nuclei - can not be explained by neutron-capture processes [1]. Therefore, other types of reactions - dominantly photodisintegration reactions - come into play. This is called the $\gamma$ process. Statistical model calculations play a crucial role in modelling this process as cross sections for many of these photodisintegration...
The nucleosynthetic s-process occurring in AGB stars from 1-6 M is responsible for creating half of the heavy elements in the universe. The s-process can be traced directly through AGB stars, or indirectly through their binary companions (Ba, CEMP-s, CH stars), as AGBs will dredge s-process material to the surface and deposit this material onto the companion.
We present data for 30 stars...
The K-Pg (Cretaceous–Paleogene) boundary at 66 Ma marks one of five major mass extinctions in Earth’s fossil history. Based on strong enrichments of platinum-group elements, Alvarez et al. [1], in 1980, suggested that the impact of a large asteroid was responsible for the K/Pg event. To exclude other causes for the mass extinction, e.g., a nearby supernova(SN)-explosion, they also searched for...
The presence of long-lived radionuclides provides insights into the solar system's history. The radionuclide $^{60}$Fe (t$_{1/2}\,$=$\,$2.6$\,$Myr) is mainly synthesized in massive stars and subsequently ejected by supernovae. Embedded into dust grains, $^{60}$Fe can enter the solar system and be deposited into terrestrial archives, where it evidences stellar explosions even after several...
Superluminous supernovae are a class of exceedingly bright transients whose luminosity cannot be comfortably explained by the standard 56Ni-decay picture. The quest for an alternative scenario has pointed at the contribution of a nascent millisecond magnetar and/or at the interaction of the supernova ejecta with a circumstellar medium surrounding the progenitor star; however, some of the...
The Al-Mg cycle is a crucial pathway in stellar nucleosynthesis. In this cycle, various aluminum (Al) isotopes are synthesized through several nuclear reactions onto magnesium (Mg) isotopes, followed by subsequent nuclear transformations within stellar environments. One of these reactions is the rp-process, in which, spin-parity assignments play an essential role in determining the rates at...
Nuclear astrophysics is a field of research that lends itself to an engaging dissemination thanks to its interdisciplinary nature. It is important to involve blind or deaf individuals in these moments of dissemination to an even greater extent. The project ‘Stelle sulla Terra’ at the University of Padua aims to achieve this by reproducing a scaled model of the ‘Bellotti’ IBF facility and...
The slow (s) and rapid (r) neutron-capture processes are major producers of elements heavier than iron. The main component of the s-process takes place in low-mass AGB stars, through a series of neutron capture reactions and beta decays, resulting in a flow that proceeds along the beta-stability valley. In this context, the neutron-capture cross sections of closed neutron shell nuclei...
The 12C+12C fusion reaction plays an significant role in our understanding of heavy element nucleosynthesis, as well as supernovae of type Ia. Two of its channels, namely $^{12}$C($^{12}$C,p)$^{23}$Na and $^{12}$C($^{12}$C,$\alpha$)$^{20}$Ne are currently under study at the Bellotti Ion Beam Facility within an energy range from 2$\,$MeV to 3.5$\,$MeV. While the first phase is focussing on...
The Bellotti Ion Beam Facility was inaugurated in 2023. It currently houses a 3.5 MV Singletron accelerator supplied by High Voltage Engineering Europe, installed inside the deep underground Laboratori Nazionali del Gran Sasso (LNGS) in Italy, where the natural cosmic ray flux is reduced by up to six orders of magnitude. The installation of the facility has been supported by the "LUNA-MV...
Carbon burning is the third stage of stellar evolution determining the final destiny of massive stars and of low-mass stars in close binary systems. Only stars with a mass larger than a critical value $M^{*}_{up}\sim10M_\odot$, can ignite C in non-degenerate conditions and proceed to the next advanced burning stages up to the formation of a gravitationally unstable iron core. Various final...
The production of neutron-rich elements at neutron densities intermediate to those of the s- and r-processes, the so-called i-process, has been identified as possibly being responsible for the observed abundance pattern found in CEMP-r/s stars. The production site may be low-metallicity stars on the Asymptotic Giant Branch where the physical processes during the thermal pulses are not well...
The reaction ${}^{22}\mathrm{Ne}(\alpha,\gamma){}^{26}\mathrm{Mg}$ is associated with several questions in nuclear astrophysics, such as the Mg isotope ratio in stellar atmospheres and the nucleosynthesis of elements beyond Fe through its competition with the neutron source ${}^{22}\mathrm{Ne}(\alpha,n){}^{25}\mathrm{Mg}$.
Due to the low stellar energies and therefore very low cross...
Accelerator mass spectrometry (AMS) is commonly the most sensitive technique for detection of long-lived isotopes and has allowed identification of $^{60}$Fe and $^{244}$Pu signals in terrestrial and lunar archives from recent nearby nucleosynthesis.
Belonging to the middle-mass region of r-process nuclides, $^{182}$Hf (T$_{1/2}$=8.9$\,$Ma) could potentially be produced in different scenarios...
Synthesis of neutron-rich isotopes is widely considered to occur via the slow neutron-capture processes (weak and main s-process). The reactions ${}^{13}\mathrm{C}(\alpha,\mathrm{n}){}^{16}\mathrm{O}$ and ${}^{22}\mathrm{Ne}(\alpha,\mathrm{n}){}^{25}\mathrm{Mg}$ are the main neutron sources for this process; the LUNA collaboration has measured the former reaction to high precision at energies...
Solar neutrinos play a significant role in constraining physical conditions in the interior of the Sun and are a unique tool to investigate its core composition. The ${}^{14}\mathrm{N}(p,\gamma){}^{15}\mathrm{O}$ cross section is the dominant error source on neutrino flux predictions. At solar energies ($15 - 50\,\mathrm{keV}$) such a cross-section is too low to be measured directly, therefore...
We have developed a new, extremely precise experimental approach for measuring the lifetimes of excited states. This method uses gamma-tracking detectors with high resolution in energy and angle.
This method has been used at GANIL, France, to measure the lifetimes of 23Mg excited states. The gamma rays were measured with the AGATA gamma-ray detector, and the ejectiles from the...
We obtain posterior distribution of equations of state (EOSs) across a broad range of density by imposing explicitly the constraints from precisely measured fundamental properties of finite nuclei, in combination with experimental data from heavy-ion collisions and astrophysical observations of radius, tidal deformability and minimum-maximum mass of neutron stars. The acquired EOSs exhibit a...
Current stellar nucleosynthesis models fail to reproduce the measured isotopic abundances in group 2 oxygen-rich presolar grains, which are characterized by large ${}^{18}$O depletions. It was proposed that cool bottom processing in low-mass AGB stars is responsible for the observed isotopic abundances. We modeled cool-bottom processing during the RGB and the AGB of $1.2M_{\odot}$ stars to...
Accelerator Mass Spectrometry (AMS) is the most sensitive technique for direct atom counting of many long-lived radionuclides. The addition of a buffer gas-filled ion cooler to the low-energy side of the AMS system opens up exciting new possibilities, especially in the mass range $60-200\,\mathrm{amu}$. The new ion cooler ILTIS, built at Helmholtz-Zentrum Dresden-Rossendorf in cooperation with...
At the end of its evolution, the collapse of a massive star's core into a proto-neutron star is the starting point for a complex sequence of events with many possible outcomes.
Specifically, very compact and rotating stars with a high mass ($M_*>16 \,M_\odot$), are likely to create a so-called ``failed core-collapse supernova'', forming a black hole surrounded by an accreting disk. It has...
$^{205}$Pb has been proposed as a cosmochronometer for the early solar system as it is only produced in the s-process and has a half-life of 17 My. This half-life can change dramatically in the stellar environment depending on the ionization stage of $^{205}$Pb and $^{205}$Tl and the thermal population of excited nuclear states. $^{205}$Pb has an excited 1/2$^-$ state at 2.3 keV that shortens...
The fate of stars with intermediate mass ($\approx 7-11 \, M_\odot$) is still not certain. In their final stages, they develop degenerate oxygen-neon cores, potentially culminating in electron capture supernovae. Both a thermonuclear explosion, as well as a collapse to a neutron star are possible, critically depending on the oxygen ignition density. Understanding the oxygen ignition process is...
Explosive stellar environments such as novae, supernovae, x-ray bursts and neutron star mergers have been identified as possible candidate sites where the majority of the heavy elements are synthesized. Understanding the underlying mechanisms of the explosions can help to shed light on the observed chemical abundances at these sites. Accurate theoretical models of these environments can be...
Currently, the explanation behind the explosion mechanism of core collapse supernovae is yet to be fully understood. New insight to this phenomena may come through observations of $^{44}$Ti cosmic $\gamma$ rays; this technique compares the observed flux of cosmic $^{44}$Ti $\gamma$ rays to that predicted by state-of-the-art models of supernova explosions. In doing so, the mass cut point of the...
New models of so-called electron-capture supernovae (ECSNe) suggest that while the full collapse of sAGB stars to a NS is still a possibility, the energy release by the electron-capture reactions can also trigger a thermonuclear runaway initiating explosive thermonuclear burning in a ''thermonuclear ECSN'' (tECSN).
Initial studies suggest that tECSNe could reproduce the solar abundances of so...
Magnetorotational supernovae are hypothesized as environments for the rapid neutron-capture process (r-process) responsible for the formation of heavy elements in our Universe. The magnetic fields within these events are a key ingredient in this process, yet their precise strength and configuration remain elusive. To address this, we analyzed comprehensive 3D MHD supernova simulations with...
Massive stars (>10M☉) undergo core-collapse supernova explosions at the end of evolution. These explosions release elements ranging from helium (produced during the stellar evolution) to iron peak synthesized in explosive nucleosynthesis. Although the explosion mechanism of core-collapse supernovae is not fully understood, 1D spherically symmetric explosion models have been...
Astrophysical thermonuclear explosions typically arise from interactions in binary star systems. Their predicted observational characteristics span a wide range in parameter space and include Type Ia supernovae, as well as other classes of transient events. Understanding and interpreting the rich set of new data expected from upcoming transient searches requires advances in modelling the...
The E1 $\gamma$-ray strengh of the Pygmy Dipole Resonance (PDR), close to the neutron threshold on the top of the low-energy tail of the Isovector Giant Dipole Resonance (IVGDR), exhausting only few percent of the TRK sum rule is known to affect significantly the radiative neutron capture cross section calculations of the astrophysical r-process [1] which is responsible for the...
Current stellar nucleosynthesis models fail to reproduce the measured isotopic abundances in group 2 oxygen-rich presolar grains, which are characterized by large ${}^{18}$O depletions. It was proposed that cool bottom processing in low-mass AGB stars is responsible for the observed isotopic abundances. We modeled cool-bottom processing during the RGB and the AGB of $1.2M_{\odot}$ stars to...
The slow (s) and rapid (r) neutron-capture processes are major producers of elements heavier than iron. The main component of the s-process takes place in low-mass AGB stars, through a series of neutron capture reactions and beta decays, resulting in a flow that proceeds along the beta-stability valley. In this context, the neutron-capture cross sections of closed neutron shell nuclei...
The production of neutron-rich elements at neutron densities intermediate to those of the s- and r-processes, the so-called i-process, has been identified as possibly being responsible for the observed abundance pattern found in CEMP-r/s stars. The production site may be low-metallicity stars on the Asymptotic Giant Branch where the physical processes during the thermal pulses are not well...
The 12C+12C fusion reaction plays an significant role in our understanding of heavy element nucleosynthesis, as well as supernovae of type Ia. Two of its channels, namely $^{12}$C($^{12}$C,p)$^{23}$Na and $^{12}$C($^{12}$C,$\alpha$)$^{20}$Ne are currently under study at the Bellotti Ion Beam Facility within an energy range from 2$\,$MeV to 3.5$\,$MeV. While the first phase is focussing on...
The detection of cosmic signatures in deep-sea, ice, and lunar samples has made an important contribution to nuclear astrophysics in recent years. In particular, ${}^{60}$Fe from near-Earth supernovae has been imprinted during the time periods $2-3$ and $7-8\,\mathrm{Myr}$ ago.
This data corroborates theoretical studies that suggest that more than $10$ SNe exploded at a distance of...
We present a relativistic density functional approach to color superconducting quark matter that mimics quark confinement by a fast growth of the quasiparticle self-energy in the confining region. The approach is shown to be equivalent to a chiral model of quark matter with medium dependent couplings. The approach to the conformal limit at asymptotically high densities is provided by a medium...
The CNO cycle plays a key role in the nucleosynthesis of massive stars and their energy production. The $^{14}\mathrm{N}(\mathrm{p},\gamma){}^{15}\mathrm{O}$ reaction is the slowest in this cycle and, therefore, controls the speed of the entire cycle, influencing the synthesis of carbon, nitrogen, oxygen and fluorine. However, investigating the reaction at astrophysically relevant energies is...
The Compton Spectrometer and Imager (COSI) is a NASA Small Explorer (SMEX) satellite mission with a planned launch in 2027. COSI operates in the $0.2-5\,\mathrm{MeV}$ gamma-ray bandpass and obtains coverage of the entire sky every day. COSI provides imaging, spectroscopy, and polarimetry of astrophysical sources, and its germanium detectors have excellent energy resolution for emission line...
The German Center for Astrophysics aims to generate knowledge and advance innovations in order to continue to position Germany at the forefront of astrophysics. It relies on broad international cooperation and strives to secure technological sovereignty through the development of new technologies and the transfer of knowledge. A particular focus is on promoting environmentally friendly...
Heavy ion storage rings have been used for nuclear astrophysics measurements for decades, and have proven themselves powerful tools for exotic mass measurements.
Recent advances in ring operation and beam intensities made measurement of nuclear reactions at rings possible. In particular, pioneering measurements were carried out at the ESR at GSI (Germany) investigating the astrophysical...
The abundances of the light elements can be spectroscopically determined by observing the low-metallicity stars. Usually, those measurements are in agreement with the Big Bang Nucleosynthesis predictions. Particularly, the Li-7 measured abundance is 3-4 times lower than expected, discrepancy known as the “cosmological Li problem”. The reaction $^3$H(α,γ)$^7$Li contributes to the production...
The $^{3}$He($\alpha,\gamma$)$^{7}$Be reaction plays a significant role in Big Bang nucleosynthesis, as well as in stellar hydrogen burning. It affects the nucleosynthesis of primordial $^{7}$Li, as well as the theoretical prediction of solar $^{7}$Be and $^{8}$B neutrino fluxes.
A measurement of its $\gamma$-ray angular distribution was performed using the 5$\,$MV Pelletron accelerator at...
Meteorites, also known as the poor scientists' space probe, are valuable samples to study the solar nebula and its constituents. Certain primitive meteorites captured the composition of the solar system and have not been altered in the 4.5 billion years since its formation. These rocks also carry nucleosynthetic anomalies that allow us to deduce stellar processes in the solar neighborhood...
The chemical enrichment history of the elements observed in the Sun and in other stars is providing crucial information about the formation and the chemical evolution of the Milky Way. The production of specific elemental ratios and isotopes can be used to constrain different uncertainties affecting galactic chemical evolution (GCE) simulations. Theoretical stellar yields are one of the major...
Studying the galactic chemical evolution with short lived radioisotopes (SLRs) has a significant advantage over using stable elements: Due to their radioactive decay, SLRs carry additional timing information on astrophysical nucleosynthesis sites.
We can use meteoritic abundance data in conjunction with a chemical evolution model to constrain the physical conditions in the last rapid...
60-Fe found in the Earth crust points to one or several core-collapse supernovae within 100-150 pc of Earth 1.5-2.5 Myr ago, probably from the young OB-associations in Scorpius, Centaurus, and Lupus.
We search for neutron stars formed in those supernovae: (i) We trace back the motion of all young neutron stars and runaway stars (whose former common multiple star system was disrupted by the...
Using a consistent statistical approach through the Backward-Forward Monte-Carlo method, we investigate both the parameter (statistic) and model (systematic) uncertainties associated with theoretical nuclear reaction rates of relevance during the i-process, and with theoretical nuclear masses of relevance during the r-process.
- For the i-process, we explore the impact on the i-process...
In 2017, a multimessenger era started with the first gravitational wave detection from the merger of two neutron stars (GW170817) and the rich electromagnetic follow-up. The most exciting electromagnetic counterpart was the kilonova. The neutron-rich material ejected during the neutron star merger undergoes an r-process that produces heavy elements and a kilonova. Moreover, observations of...
Heavy elements like gold and uranium are produced via the rapid neutron-capture (r-)process. This process only occurs in rare explosive events in the Universe, like supernovae and neutron star mergers, making it highly challenging for astronomers to gather direct observations of the element creation. Likewise, it is difficult for nuclear physicists to recreate and study the nuclear process in...
The astrophysical rapid-neutron capture process (r-process) of explosive nucleosynthesis is responsible for the formation of half of the heavy nuclei above Fe. Actinides are produced towards the end of this process, when the neutron flux is expected to be minimal, and it is supported also by fission processes. Given that the r-process path runs far away from the accessible species, in this...
The ${}^{140}$Ce(n,$\gamma$)${}^{141}$Ce is recognized as an important reaction in the flow of neutron-capture nucleosynthesis due to the neutron-magic character of ${}^{140}$Ce and a corresponding small neutron capture cross section. We present here [1] measurements of the neutron-capture Maxwellian-averaged cross section (MACS) of stable cerium isotopes performed by activation in the...
About half of the heavy elements in nature are created at the end of core helium burning in massive stars (weak $s$-process) and during the AGB phase of low-mass stars (main $s$-process). These astrophysical environments have been identified as $s$-process sites because reactions are available that produce neutrons on an appropriate time scale and quantity. The...
$^{26}$Al and $^{60}$Fe are two short-lived radioactive nuclei that can be used as tracers of the star formation. In the next years, COSI, the new $\gamma$-ray instrument by NASA will be launched and will provide us with a new insight of the distribution of these two elements in the Milky Way. In view of these new upcoming measurements, by means of a detailed 2D chemical evolution model I...
Cross-sections for neutron-induced reactions with molybdenum is relevant in various scientific fields ranging from nuclear astrophysics to nuclear technologies. In addition to its astrophysical role, molybdenum isotopes can be found in fission power plants as fission products and the use of this material is under study for future improved reactors. Molybdenum is found in pre-solar silicon...
To interpret stellar spectra 1D hydrostatic model atmospheres are most often used as a compromise between accuracy and computational cost. However, such models do not treat convection accurately and rely on approximating it with varying degrees of success. We present a new grid of 3D hydrodynamic CO5BOLD model atmospheres and use it with 3D non-equilibrium radiative transfer code MULTI3D to...
Due to the Coulomb barrier or the low-intensities of radioactive ion beams (or both!), indirect approaches to determining thermonuclear reaction rates are vital. There are many different tools, ranging from improving spectroscopy of nuclei to constrain resonance properties using charged-particle or $\gamma$-ray spectroscopy to identify resonance states and determine their spins and parities,...
ELISSA is a 4π silicon strip detector array implemented at the ELI-NP facility for measurements of photodissociation reactions using high-brilliance, quasi-monoenergetic gamma beams. The array consists of three rings of 35 single-sided X3 detectors and two end-caps made up of eight double-sided QQQ3 detectors. However, multiple configurations are possible with the YY1, MMM, and QQQ3 detectors...
Obtaining reliable cross sections for neutron-induced reactions on unstable nuclei nuclei is crucial to our understanding of the stellar nucleosynthesis of heavy elements. However, the measurement of these cross sections is very complicated, or even impossible, due to the radioactivity of the targets involved. Our aim is to circumvent this problem by using the surrogate-reaction method in...
Live radionuclides that were synthesised and ejected by stellar explosions, dispersed in the interstellar medium and subsequently deposited on Earth provide key insights about the astrophysical history of the solar neighbourhood and heavy element nucleosynthesis. The influx of supernova-produced $^{60}$Fe (t$_{1/2}$$\,$=$\,$2.6$\,$Myr) about 2.5$\,$Myr ago was reported several times within the...
Accounting for out-of-NSE (nuclear statistical equilibrium) r-process nucleosynthesis is one of the most sought-after goals in the (numerical) modelling of binary neutron star (BNS) mergers. While post-processing analysis via full nuclear networks is a reliable technique, the computational and storage costs prevent such calculations to be directly coupled to hydrodynamics codes, thus...
We have developed a compact detector system that utilizes an active-target TPC (Time Projection Chamber) to measure the $^{12}$C$(\alpha,\gamma)^{16}$O reaction. This system includes a 3-T superconducting magnet, a low-pressure He-gas TPC, and a LaBr$_3$(Ce) detector array. The proposed experiment, called COREA (Carbon Oxygen Reaction Experiment with Active-target TPC) experiment, will take...
Masterclasses are one-day outreach events for high school students, introducing them to topics of current research. Within the framework of the EU project ChETEC-INFRA, Masterclasses on Nuclear Astrophysics have been developed. This interdisciplinary field of science provides a new didactic perspective on nuclear and astrophysical processes by addressing the link between these two subjects....
The lowest metallicity stars that still exist today represent a window into the early Universe. Studying these stars gives us a local avenue to guide our understanding of star formation and supernova feedback in the early Universe, the early build-up of galaxies like our Milky Way, and the epoch of reionization.
In this talk I will review how we have become very efficient at finding these...
The recent multimessenger detections of signals from neutron star binaries has opened a new era also for the study of high density physics. With interior densities that can exceed those of an atomic nucleus, and low temperatures (at least in mature systems) compared to the Fermi temperatures of the constituents, neutron stars allow to probe very different and complementary regimes of the QCD...
The majority of elements beyond the Fe peak are produced by neutron capture processes which can be rapid (r-process) or slow (s-process) with respect to the $\beta$-decay in nuclei. Understanding which are the astrophysical formation sites of these two processes has become one of the major challenges in chemical evolution. In particular, the r-process sites are still under debate, with...
Massive stars play a crucial role in shaping the chemical composition of galaxies, enriching the interstellar medium with both light and heavy elements previously synthetized in the star through nuclear reactions. Recent advancements in stellar modelling have highlighted the beneficial effects of rotation in massive stars, enhancing the nucleosynthesis of certain elements, especially at low...
Massive stars play an important role in the synthesis of new elements in the Universe. To understand the nucleosynthetic wind-yields of such stars, there are three key-ingredients; the nuclear reaction-rates, internal mixing processes, and the stellar winds. We focus on the effects of interior mixing processes. Up to now, the calculations of stellar yields have relied on stellar evolution...
Galactic chemical evolution calculations provide invaluable feedback between abundance surveys and stellar and nuclear physics models. Until recently, only yields from single stars have been available, so chemical evolution codes do not have the capability to build a mixed population of binary and single stars. This is a serious limitation, as most stars – particularly the most massive – form...
Atomic cascades are ubiquitous in nature and have therefore been explored within many different scenarios, from atoic precision measurements to the modeling of astrophysical spectra, and up to the radiation transport in neutron-star mergers. We here introduce and discuss a classification of atomic cascades and demonstrate how they can be modeled efficiently [1,2].
In practice, however, most...
Our knowledge about dense matter explored in the cores of neutron stars remains limited. Fortunately, the detections of gravitational waves emitted from the merger of neutron stars and the corresponding electromagnetic signals provide a new way of studying supranuclear-dense material. Making use of the strength of multi-messenger astronomy, one can combine the information obtained from...
We present a new nucleosynthesis process that may take place on neutron-rich ejecta experiencing an intensive neutrino flux. The nucleosynthesis proceeds similarly to the standard $r$-process, a sequence of neutron-captures and beta-decays, however with charged-current neutrino absorption reactions on nuclei operating much faster than beta-decays. Once neutron capture reactions freeze-out the...
Neutron-capture processes made most of the abundances of heavy elements in the Solar System, however they cannot produce a number of rare neutron deficient stable isotopes (p-nuclei) lying on the left side of the valley of stability. The $\gamma$-process is recognised and generally accepted as a feasible process for the synthesis of p-nuclei in core-collapse supernovae. However this scenario...
In high energy astrophysical processes involving compact objects, such as core-collapse supernovae or binary neutron star mergers, neutrinos are likely to play an important role in the synthesis of nuclides. Neutrinos in these environments can experience collective flavor oscillations driven by neutrino-neutrino coherent forward scattering. Recently, there has been interest in exploring...
Experimental data collected in the last two decades give a clear indication that the low-energy alpha-nucleus optical potential ($\alpha$-OMP) is a crucial and not sufficiently known nuclear physics parameter in the modeling of the $\gamma$-process of heavy element nucleosynthesis. A new $\alpha$-OMP called Atomki-V2 has been developed for low energy nuclear astrophysics purposes [1]. This...
The discovery of a slowly inspiralling binary system of two neutron stars by Hulse and Taylor in 1974 made clear that the final fate of such a system would be a very violent collision between the compact stars and that -at the very least- "something interesting" would happen. Based on indirect and mostly theoretical arguments, such collisions where connected to gamma-ray bursts and also to the...
Understanding the origin of the elements, particularly elements heavier than iron, is consistently identified as a major research challenge in nuclear physics. Meeting this challenge demands new approaches to overcome extreme technical difficulties posed by reaction studies, especially those that necessitate the use radioactive ion beams. In this talk, I will present the recent progress of...
Nuclear physics plays an important role for many astrophysics applications. Nucleosynthesis simulations of heavy elements, for example, require nuclear inputs across the whole nuclear chart, far beyond the region where experimental data is available. Likewise, the description of the extremely dense neutron-rich matter in neutron stars (NS) is a challenge for nuclear physics and...
I'll present the results from a self-consistent 2-dimensional (ray-by-ray) radiation-hydrodynamic simulation of BNSM ejecta with an online nuclear network (NN) up to the days timescale. An initial numerical-relativity ejecta profile composed of the dynamical component, spiral-wave and disk winds is evolved including detailed $r$-process reactions and nuclear heating effects. A simple model for...
Since the first direct detection of gravitational waves in 2015, we have gained an entirely new observation window to the universe. The sensitivity of these interferometers is so incredible that the quantum effects of the laser light have become limiting. Ultra-precisely stabilised lasers do not suffice; non-classical light is already routinely employed in the current generation of...
Neutron star mergers lead to the ejection of multiple outflow components. Many existing neutron-star merger models cover only the first tens of milliseconds after the merger and can therefore only describe the early, dynamical ejecta. However, further matter ejection can take place during several seconds of evolution of the merger remnant. In this talk I will present our recent study [1]...
The detection of the kilonova AT2017gfo has provided us with a wealth of observations. However, to interpret these observations to obtain information about the underlying merger ejecta, including r-process nucleosynthesis, we are reliant on kilonova modelling. The majority of binary neutron star ejecta models considered when simulating kilonovae have been in 1D, or even idealised toy models,...
Type-I X-ray bursts are interpreted as thermonuclear runaways in the atmospheres of accreting neutron stars in close binary systems. These astronomical events exhibit brief, recurrent bursts of intense X-ray emission and represent some of the most frequent and violent stellar explosions to occur in our Galaxy. Recently, space-borne satellites such as the Rossi X-ray Timing Explorer (RXTE) and...
The $^{15}$O($\alpha$,$\gamma$)$^{19}$Ne reaction is a key breakout route from the hot CNO cycle in explosive environments such as type I X-ray bursts. Determining an accurate cross section for the relevant resonant states is critical for a better understanding of the X-ray burst energy production and light-curves, and of the subsequent nucleosynthesis through the $\alpha$p- and...
The ${}^{16}$O(p,$\alpha$)${}^{13}$N reaction plays a key role in controlling the Ca/Si and Ca/S ratios synthesized during $\alpha$-rich oxygen burning in Type Ia supernovae (SNIa). This reaction feeds the $\alpha$-rich burning branch by converting ${}^{16}$O into ${}^{12}$C via the chain of ${}^{16}$O(p,$\alpha$)${}^{13}$N($\gamma$,p)${}^{12}$C. Moreover, the ${}^{16}$O(p,$\alpha$)${}^{13}$N...
In this presentation, the carbon-enriched metal-poor (CEMP) stars will be briefly reviewed. Recent progress in determining the stellar parameters, on the challenges to get benchmark stars within this category, as well as on nucleosynthetic processes that shape the composition of CEMP stars, will be reviewed. CEMP stars exhibit a rich diversity, with at least four distinct types identified. The...
The ${}^{12,13}\mathrm{C}(\mathrm{p},\gamma){}^{13,14}\mathrm{N}$ are the first reactions of the CNO cycle, active in both hydrostatic and explosive hydrogen burning. They contributes to the ${}^{12}\mathrm{C}$/${}^{13}\mathrm{C}$ isotopic ratio, observed in stellar atmosphere in meteoritic grains and in the interstellar medium. The ${}^{12}\mathrm{C}$/${}^{13}\mathrm{C}$ is a useful tool to...
Fusion reactions involving carbon and oxygen are crucial for the understanding of massive stars and of the nucleosynthesis. Besides $^{12}$C+$^{12}$C, measurements of neighbour light systems as $^{12}$C+$^{16}$O and $^{16}$O+$^{16}$O are scarce although relevant for the modelling of late carbon burning, oxygen burning in massive stars as well as explosive carbon burning of Type Ia...
The CNO cycle is the main energy production mechanism in stars heavier than our Sun, defining both their evolution and lifespan. The solar $\nu$-flux from the CNO cycle has been recently measured by the Borexino collaboration and it could provide an independent estimate of the solar metallicity, i.e.\ the CN abundance in the core of the sun.
The equilibrium of the CNO cycle is ruled by the...
The triple-alpha process is one of the most fundamental processes in stellar nucleosynthesis, and in particular, the stellar production of carbon. This process entails the fusion of three helium nuclei to form an intermediate state in $^{12}$C. This intermediate state can decay back into its three constituent alpha particles or radiatively decay to form stable $^{12}$C. At temperatures between...
We present a newly developed jet and extended windowless gas target system, tailored to meet the precision measurement demands of modern nuclear astrophysics. Our system can be operated either in jet or extended modes without necessitating modifications in pumping power. Real-time monitoring of a jet, facilitated by laser interferometry techniques, ensures control of target parameters during...
To understand and model element synthesis and energy budget in stars a large number of nuclear reaction cross sections must be known. For explosive stellar scenarios, like supernovae or x-ray bursts, this heavily involves nuclei beyond stability. However, due to the challenges inherent to related experiments, the lack of available experimental data in this domain is severe.
A new method for...
Classical novae are stellar thermonuclear explosions involving a white dwarf accreting material from a companion star. Early in the Galactic history, these explosions proceeded differently, mainly due to the accretion of sub-solar metallicity material onto the white dwarf. It has been proposed that these primordial nova explosions produce a different abundance pattern compared to their...
$^{22}$Na (T$_{1/2}$ = 2.6 y) is of high interest for space-based γ-ray astronomy because its direct observation could constrain classical nova models. Although the characteristic 1275 keV β-delayed γ decay radiation has not been observed yet, future γ-ray telescopes may detect the decay with high sensitivity. To link these observations with nova model predictions, nuclear data are needed. The...
The nucleosynthesis process involving neutron captures during stellar helium burning, known as the s-process, contributes to roughly half of the elements heavier than iron. As for Asymptotic Giant Branch (AGB) stars, they are major producers of nuclei from Sr to Pb. Despite significant theoretical progress in recent decades, uncertainties persist in AGB models, notably regarding the mechanism...
With the recent large-scale surveys such as APOGEE, GALAH, LAMOST, among others, our knowledge about stellar nucleosynthesis, as well as the chemical evolution and composition of the Milky Way, has been growing quickly. However, surveys have a trade-off between data volume and data quality, to allow probing the chemistry of the Galaxy as a whole. That results in some potentially interesting...
We present evidence that the heavy-element abundances in maybe most carbon-enhanced metal-poor stars point to i-process nucleosynthesis, at neutron densities intermediate between those of the s- and r-processes. The i process may occur in a helium convective zone that entrains hydrogen from an adjacent H-rich envelope, for example in rapidly-accreting white dwarfs, like those considered to...
An accurate understanding of the slowest reaction of the CNO cycle, the $^{14}$N(p,$\gamma$)$^{15}$O, is essential for estimating the lifetimes of massive stars and globular clusters. Additionally, it plays a crucial role in determining the CNO neutrino flux emitted by the Sun. Despite the significant efforts over the last twenty years, including pioneering underground measurements made by the...
An accurate understanding of the slowest reaction of the CNO cycle, the $^{14}$N(p,$\gamma$)$^{15}$O, is essential for estimating the lifetimes of massive stars and globular clusters. Additionally, it plays a crucial role in determining the CNO neutrino flux emitted by the Sun. Despite the significant efforts over the last twenty years, including pioneering underground measurements made by the...
The Maxwellian Averaged Cross Section (MACS) is a very relevant quantity regarding stellar nucleosynthesis. To consider all possible scenarios, the stellar temperatures of interest are within the range of $kT = 5\,\mathrm{keV}$ up to $120\,\mathrm{keV}$. Traditionally, the standard value taken has a reference has been $30\,\mathrm{keV}$, because the equivalent neutron distribution can be...
The Maxwellian Averaged Cross Section (MACS) is a very relevant quantity regarding stellar nucleosynthesis. To consider all possible scenarios, the stellar temperatures of interest are within the range of $kT = 5\,\mathrm{keV}$ up to $120\,\mathrm{keV}$. Traditionally, the standard value taken has a reference has been $30\,\mathrm{keV}$, because the equivalent neutron distribution can be...
The ${}^{19}\mathrm{F}(p,\alpha){}^{16}\mathrm{O}$ reaction is important for understanding the fluorine abundance in the outer layers of AGB stars and it might also play a role in hydrogen-deficient post-AGB star nucleosynthesis. Up to now, theoretical models overproduce F abundances in AGB stars with respect to the observed values. Besides, for the $(p,\alpha_0)$ channel there are...
Astrophysical observations of neutron stars allow us to study the physics of matter at extreme conditions which are beyond the scope of any terrestrial experiments. In this work, we perform a Bayesian analysis putting together the available knowledge from the nuclear physics experiments, observations of different X-ray sources, and gravitational wave events to constrain the equation of state...
Astrophysical observations of neutron stars allow us to study the physics of matter at extreme conditions which are beyond the scope of any terrestrial experiments. In this work, we perform a Bayesian analysis putting together the available knowledge from the nuclear physics experiments, observations of different X-ray sources, and gravitational wave events to constrain the equation of state...
Neutron capture reactions in stars are responsible for forming about 99% of the elemental abundances heavier than Fe. The stellar neutron capture cross sections are the key nuclear physics input for s-process studies. Accurate normalization standards play an important role in (n,$\gamma$) reaction measurements. Two experiments were performed to determine the Maxwellian averaged cross section...
We investigate the possibility that i-process nucleosynthesis could be activated in the evolution of interacting binaries with a CO WD and a He-rich donor. In this systems the main neutron source is the ${}^{22}\mathrm{Ne}(\alpha,\mathrm{n}){}^{25}\mathrm{Mg}$ reaction occurring during recurrent He-flash episodes triggered by mass transfer. We also discuss the potential contribution of these...
We investigate the possibility that i-process nucleosynthesis could be activated in the evolution of interacting binaries with a CO WD and a He-rich donor. In this systems the main neutron source is the ${}^{22}\mathrm{Ne}(\alpha,\mathrm{n}){}^{25}\mathrm{Mg}$ reaction occurring during recurrent He-flash episodes triggered by mass transfer. We also discuss the potential contribution of these...
Binary neutron star (BNS) mergers provide an excellent cosmic laboratory for understanding the origin of heavy ($Z > 26$) elements, which has been a long-standing mystery in astronomy. In the neutron-rich material ejected from the BNS merger, heavy elements are synthesized via rapid neutron capture (r-process). The radioactive decay of such elements produces emission in the...
