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Details of the explosion mechanism of core-collapse supernovae (CCSNe) are not yet fully understood. There is now an increasing number of successful examples of reproducing explosions in the first-principles simulations, which have shown a slow increase of explosion energy. However, it was recently pointed out that the growth rates of the explosion energy of these simulations are insufficient...
Core-collapse supernovae mark the death of massive stars above ~8-10 Msun. In this spectacular explosion, elements are synthesized and ejected. The details of the isotopes produced depend on many factors, including the composition of the star prior to explosion, the weak reactions during the collapse and onset of the explosion, and the strength of the explosion. In this talk, I will highlight...
The very intriguing chemical properties of the carbon isotopes can generate unique
molecular compounds within the interstellar and interplanetary media. As stellar evolutionary
processes collect plasma, gas, and dust, energy provided by shock waves, cosmic rays, and ion
bombardment may stimulate chemical reactions on the surface of grains, which provide a
substrate for the nucleation and...
I will present a short historical overview of the ideas regarding
a) our theoretical understanding of the production of several key radioactivities in gamma-ray astrophysics
b) their role as probes of various astrophysical sites (physics of supernovae, distribution of massive stars in the Galaxy, etc)
I would like to discuss together the diversity of observed and predicted 60Fe/26Al ratios: in the Galaxy, in core-collapse supernova models, in the early Solar System, and in Earth's samples, and how could all these be reconciled.
Astrophysical observations of radioactive isotopes, like 26Al, 44Ti, or 60Fe, provide insight into the nucleosynthesis of stellar cores [1]. Recently, the radioactive molecule 26AlF was unambiguously astronomically identified towards the object CK Vul [2] by rotational transitions in the microwave spectral region, using the radio telescope observatory ALMA and other telescope facilities. In...
Chemically peculiar stars, such as the recently discovered metal-poor ([Fe/H]$\sim$-1) phosphorus-rich stars, query the current theories on stellar nucleosynthesis and galactic chemical evolution. Consequently, the origin of these stars, their progenitors and hence the source of phosphorus in the Galaxy remains unclear.
In this study, we achieved a remarkable enlargement of the P-rich stars...
A recent study by Côté et al. (2021) has shown that ratio of the observed abundances of short-lived radioisotopes $^{129}$I and $^{247}$Cm in the early solar system (ESS), that are almost exclusively produced by r-process, can be used to directly constrain the "last" r-process source that contributed before the formation of the Solar system due to fact that these two isotopes have...
For the increased interest on the impact of nu-p process in the search of an answer to the heavy element production puzzle in core-collapse supernovae, a direct (n,p) reaction measurement with the radioactive $^{56}$Ni (a half-life of 6 days) was performed at Los Alamos Neutron Science Center (LANSCE). The radioactive 56Ni was produced by irradiating protons on a $^{59}$Co foil through the...
There is a growing consensus in recent multi-messenger astronomy that the neutron-star merger (NSM) could be a possible site for the production of heavy elements including long-lived radioactive nuclei. We will first discuss that the collapsar, which is very massive single star collapsing to a black hole, and core-collapse supernovae (CCSNe) such as magneto-hydrodynamically driven-jets and...
On January 1st 2020, eight cameras of the PRISMA fireball network detected a very bright bolide over the skies of northern-central Italy. Thanks to these observations, we were able to locate a strewn-field of few square kilometers and recover two specimens, weighing 3.1 g (F1) and 52.2 g (F2), just three days after the fall.
Laboratory analysis on the Cavezzo meteorite showed substantial...
Neutron-rich nuclei around the closed neutron shell N = 126 are of great importance for understanding the astrophysical r-process, specially for the solar r-abundance distribution [1,2]. These radioactive isotopes can also be used as projectiles for synthesizing super-heavy nuclei which is one of the most interesting challenges in nuclear physics. In the present work, inspired from recent...
The 13C(α,n)16O reaction is the main neutron source for the slow neutron capture process (s-process) in the Asymptotic Giant Branch (AGB) stars [1] and for the intermediate process (i-process) [2]. It is activated at the temperature around T = 0.1 GK [3,4] and 0.2 GK [2], which correspond to the Gamow windows of Ecm = 0.15 – 0.3 MeV and 0.2 – 0.54 MeV, for the s- and i-processes, respectively....
Sources of nucleosynthesis may occur in different interstellar environments, from empty fields through clusters of sources, such as in massive-star groups. Such differences are important for the recycling times and efficiencies towards next-generation star formation. With radioactivity from 26Al we have a tool to trace ejecta flows over millions of years. With 60Fe (and 244Pu) in terrestrial...
The recent upgrade of the CERN n_TOF neutron-spallation target has resulted in improved experimental conditions regarding neutron-energy resolution and background level. A concomitant effort has been also made in terms of detection systems, thereby remarkably improving some limitations of previous set-ups. These upgrades, together with a major effort on sample production at PSI and ILL, have...
We have developed Galactic Chemical Evolution (GCE) models to understand the spatial and temporal distribution of the short-lived radionuclides (SLRs), $^{26}$Al, $^{36}$Cl, $^{41}$Ca, $^{53}$Mn, and $^{60}$Fe in the Milky way galaxy. In our simulations, the galaxy is radially divided into eight annular rings of 2 kpc width from 2-18 kpc to study the evolution of each galactic ring...
In addition to the insights gained by studying the galactic evolution of chemical elements, short lived radioisotopes contain additional information on astrophysical nucleosynthesis sites.
Meteorites can carry information about the nucleosynthetic conditions in the early Solar System using short lived radioisotopes [1][2], while detections of live isotopes of cosmic origin in the deep sea...
Unlike the Hertzsprung–Russell diagram for stars, there remains no formal classification for solid exoplanets composed of varying proportions of gas, rock+metals and ice. Still, as with stars, planetary mass and composition – expressed in geochemical and cosmochemical terms – mold bulk physical characteristics. Two physical attributes control terrestrial-type planet interior dynamics:...
In this study, the cross-sections of 155Gd(n,g)156Gd reaction in the 0-0.5 MeV incident energy range were evaluated by using TALYS 1.95 nuclear reaction code. Available experimental cross-section values of this reaction were obtained from EXFOR, Experimental Nuclear Reaction Library of IAEA. Both, experimental and theoretical cross section values were interpreted by using graphical...
The recent detection of interstellar Pu-244 in deep-sea samples points to an influx into the solar system of short-lived r-process nuclides over the past 10 million years. The Pu was found in a terrestrial sample that has grown over million years, together with supernova (SN)-produced Fe-60 (2.6 Myr half-life). Pu-244 is radioactive (81 Myr) and must have been produced within a few half-lives;...
The astrophysical rapid neutron-capture process (r-process) is believed to be responsible for the production of approximately half of the chemical elements heavier than iron. The accurate modelling of the r-process nucleosynthesis needs reliable experimental nuclear data, especially for nuclei around closed neutron shells serving as waiting points, this has been shown by sensitivity studies...
The disagreement between abundances of observed $^{7}$Li in metal-poor halo stars and primordial $^{7}$Li as predicted by Big Bang Nucleosynthesis (BBN) theory is unsolved for decades. Before considering new physics beyond standard model, recent works tried to search for a nuclear physics solution. This includes studying the cross sections of relevant nuclear reactions, particularly those...
The cross section of $\rm ^7Be(p,\gamma)^8B$ represents one of the more important reaction for the prediction of high energy component of solar neutrino spectrum and it has also a direct impact on the $\rm ^7Li$ abundance after the Big Bang Nucleosynthesis. The importance of this reaction triggered an intense experimental work over the last decades, where discrepancies were observed between...
Neutron induced reactions on unstable nuclei play a significant role in the nucleosynthesis of the elements in the cosmos. Their interest range from the primordial processes occurred during the Big Bang Nucleosynthesis up to the “stellar cauldrons” where neutron capture reactions build up heavy elements. In the last years, several efforts have been made to investigate the possibility of...
Recent measurements of the $^7$Be abundance in nova ejecta show that
it may exceed theoretically predicted values by an order of magnitude.
I will demonstrate that this discrepancy can be significantly reduced
if a nova explosion model takes into account that, according to
observations, nova envelopes are enriched in $^4$He. I will also explain
why the assumption that nova accreted...
We studied the distribution and kinematics of metal flows
in the Milky Way with INTEGRAL observations of the 1.8 MeV
radioactive decay line of 26Al and hydrodynamic simulations.
The gamma rays pinpoint the flows of freshly produced metals
from massive stars about 1 Myr (decay time) after ejection.
We find in concordance from simulations
and observations that 26Al is mostly ejected...
The properties of relativistic jets, their interaction with the ambient environment, and particle acceleration due to kinetic instabilities are studied self-consistently with Particle-in-Cell simulations. An important key issue is how a toroidal magnetic field affects the evolution of an electron-positron and electron-proton jets, how kinetic instabilities such as the Weibel instability (WI),...
The relic of short-lived radioactive isotopes (SLRs) with half-lives between 0.1 to 100 Myr can be used to probe the origin of the Solar System. While these isotopes were made in stars shortly before the formation of the solar system, their comparison with theoretical stellar models is extremely challenging. In this talk I discuss the comparison between the signature of 15 SLRs in different...
For 20 years, the spectrometer SPI on INTEGRAL was and still is the only gamma-ray telescope to observe active nucleosynthesis in the Milky Way. The nuclear line emissions of the 26Al decay from massive stars, 22Na and 7Be decay from novae, 44Ti and 56Co decay from supernovae — all have been studied with SPI. Because of this long exposure time and steady improvements for handling the...
The astrophysical sites where $r$-process elements are synthesized remain mysterious: it is clear that neutron-star-mergers (kilonovae, KNe) contribute, and some classes of core-collapse supernovae (SNe) are also possible sources of at least the lighter $r$-process species. The discovery of $^{60}$Fe on the Earth and Moon implies that one or more astrophysical explosions have occurred near the...
Various nucleosynthesis studies have predicted the ejection of rapid neutron capture r-process elements. They include (i) core-collapse supernovae with a very weak r-process, possibly producing trans-Fe elements Sr, Y, Zr (and continuing to slightly higher mass numbers), (ii) quark-deconfinement supernovae with a weak r-process contribution (including Eu in small amounts), (iii)...
Radioactive isotopes play an increasingly important role in our understanding of the Universe [Die18]. The benefits of observing them are two-fold; the presence of a given radioactive isotope itself provides a signature to probe the stellar nucleosynthesis processes that created it, and its radioactive half-life acts as a sensitive tracer of the timescale of the dynamics involved in its...
$\alpha$-induced reactions play an essential role in various astrophysical scenarios. For intermediate mass and heavy target nuclei, various $\alpha$-nucleus optical model potentials (AOMP) predict reaction rates which may differ by orders of magnitude. This wide range of predictions complicates nucleosynthesis calculations in reaction networks, in particular for the $p$-process with uncertain...
The radioactive nucleus $^{44}$Ti is thought to be produced in Core-Collapse Supernovae (CCSNe) with the amount produced being sensitive to internal dynamics of the explosion. As such, $^{44}$Ti is a potential diagnostic tool for understanding the behaviour of these stellar explosions.
The amount of $^{44}$Ti produced depends not only on the production reactions but also on the destruction...
The nucleosynthesis of elements heavier than iron in stars is one of the most relevant topics in nuclear astrophysics. The neutron-capture processes made most of the abundances of heavy elements in the solar system, but they are not able to make a number of rare proton-rich stable isotopes ($p$-nuclei) lying on the left side of the valley of stability. The $\gamma$-process, i.e. a chain of...
Inertial fusion laser-induced implosions at the National Ignition Facility (NIF) are a unique environment to reproduce astrophysical conditions in the laboratory. The laser energy is used to compress and heat a capsule filled with deuterium-tritium fuel to conditions (density, temperature, and pressure) comparable to or exceeding those in the center of stars. Recent experiments at NIF first...
Using our code Fornax we have simulated the collapse and explosion of the cores of many massive-star models in three spatial dimensions. This is the most comprehensive set of realistic 3D core-collapse supernova (CCSN) simulations yet performed and has provided very important insights into the mechanism and character of this 50-year-old astrophysical puzzle. I will present detailed results...
Despite considerable progresses over the past decades, the origin of trans-iron elements 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 isotopic signature of some pre-solar grains and the chemical...
Heavier elements then helium are created inside stars; alpha elements are mainly produced from core-collapse supernovae, while the majority of iron-peak elements are from Type Ia supernovae. Neutron-capture elements are produced from AGB stars, electron-capture supernovae, magneto-rotational supernovae, and neutron-star megers. Mass loss from AGB stars and (rotating) massive stars produce a...
The radioactive isotope $^{10}$Be is among those that have been present when the solar system formed. We review the production of this isotope in core-collapse supernovae via the $\nu$-process considering results from modern multi-dimensional simulations, as well as the sensitivity to nuclear reactions.
Recent nuclear experiments suggest that the cross-section of the most important...
The quantity of radioactive isotopes in a planet's mantle and the evolution of its heating due to the isotopes' radioactive decay determines the capability of that planet to develop geological features associated with a habitable environment, such as surface crust and plate tectonics. When our solar system was formed, large quantities of Potassium (K), a major element available in the...
Aim: To study the effect of uncertainty in 23Mg(p,γ)24Al reaction rate occurring in O-Ne and C-O novae at Classical Nova temperatures by performing a comparative study of one-zone nova nucleosynthesis for different rates of this reaction from the JINA-Reaclib database references.
Background: Stellar burning sites are the primary sources of vast majority of elements heavier than...
Simulations of explosive nucleosynthesis in novae predict the production of the radioisotope $^{22}$Na. Its half-life of 2.6 yr makes it a very interesting astronomical observable by allowing space and time correlations with the astrophysical object. This radioisotope should bring constraints on nova models. It may also help to explain abnormal $^{22}$Ne abundance observed in presolar grains...
Various global parameters of compact stars can be related via some empirical relations, that are
independent of the equation of state (EOS). These are known as universal relations. They seem to
hold for the maximum mass and the corresponding radii of non-rotating and maximally rapidly
rotating configurations, as well as their moment of inertia. Numerous studies have focused on the
case of...
Decay rates have a significant effect on the abundance of branching point elements and short-lived nuclei. Thus, a correct description of the decay rates is essential for the accurate study of the s-process in AGB stars. The dppns45 post-processing nucleosynthesis code calculates the changes in the abundances of isotopes due to mixing and nuclear burning after the detailed stellar structure...
Sensitivity studies have identified $^{30}$P$(p,\gamma)^{31}$S as crucial for understanding nucleosynthesis of $A\geq 30$ nuclides in oxygen-neon (ONe) novae, affecting the calibration of nuclear thermometers and the identification of the origins of $^{30}$Si-enriched presolar grains. A radioactive beam experiment was performed at the National Superconducting Cyclotron Laboratory to measure...
The $^{26}$Al short-lived radioactive nucleus is the source of the observed galactic diffuse emission at 1.8 MeV. While different sources of $^{26}$Al have been explored, such as AGB stars, massive stars winds, and supernovae, the contribution of very massive stars have never been studied.
We present new results on the stellar wind contribution of very massive stars, i.e. stars with...
