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the chemical evolution of the universe is governed by the chemical yields from stars, which in turn is determined primarily by the initial stellar mass. even stars as low as 0.9 solar mass can, at low metallicity, contribute to the chemical evolution of elements. stars less massive than about 10 solar mass experience r... | stellar yields - models and observations |
new shell-model hamiltonians which can successfuly describe spin-dependent transition rates in nuclei are applied to study nuclear weak processes in stars. new v-induced reaction cross sections in 12c and 56fe evaluated by the new hamiltonians are shown to reproduce well the experimental data. nucleosynthesis of light ... | spin responses in nuclei and nuclear weak processes in stars |
in the concordance cosmology, galaxies are formed hierarchically. metal-poor stars in the stellar halo are thought to be relics of stars formed in dwarf galaxies in the early universe. in order to investigate metal enrichment history in the early universe, we have been built the chemical evolution model with merger tre... | chemical evolution of r-process elements in the hierarchical galaxy formation |
radiative α capture on 34s can impact nucleosynthesis in several astrophysical environments, including oxygen burning, explosive oxygen burning (type ii supernovae), and type ia supernovae. however, there exist discrepancies in the literature for the resonance strengths of two strong resonances within the gamow window ... | direct measurement of several resonance strengths and energies in 34s(α , γ) 38 ar within the t = 2 . 2 gk gamow window with dragon |
neutrinos from dense environments are connected to the longstanding open questions of how massive stars explode and what are the sites where r-process elements are made. flavor evolution and neutrino properties can influence nucleosynthetic abundances. gw170817 has given indirect evidence for r-process elements in bina... | neutrinos : from the r-process to the diffuse supernova neutrino background |
neutrinos from dense environments are connected to the longstanding open questions of how massive stars explode and what are the sites where $r$-process elements are made. flavor evolution and neutrino properties can influence nucleosynthetic abundances. gw170817 has given indirect evidence for r-process elements in bi... | neutrinos: from the r-process to the diffuse supernova neutrino background |
the production of heavy-mass elements due to the rapid neutron-capture mechanism (r-process) is associated with astrophysical scenarios, such as supernovae and neutron-star mergers. in the r-process the capture of neutrons is followed by β-decays until nuclear stability is reached. a key element in the chain of nuclear... | limits on active-sterile neutrino mixing parameters using heavy nuclei abundances |
the aim of this study is to investigate the accretion of matter onto a compact gravitating remnant (neutron star) in the central region of the expanding shell of a type ii supernova. computations of an explosion with the energetics of a type ii supernova have been performed to derive the structure of matter in the vici... | gamma-ray emission during the accretion of matter from a supernova envelope onto a compact remnant |
in dense environments, standard and non-standard neutrino interactions with the background particles trigger a variety of flavor mechanisms, which can impact r-process nucleosynthetic abundances. future observations of a(n) (extra)galactic supernova will tell us about properties of neutrinos and of the astrophysical so... | neutrino flavor evolution in dense environments and the r-process |
we discuss light-curve and spectral properties of ultra-stripped core-collapse supernovae. ultra-stripped supernovae are supernovae with ejecta masses of only ~0.1m ⊙ whose progenitors lose their envelopes due to binary interactions with their compact companion stars. we follow the evolution of an ultra-stripped supern... | light-curve and spectral properties of ultra-stripped core-collapse supernovae |
about half of the elements of the periodic table that are present today in the solar system were synthesized before the formation of the sun via a rapid neutron capture process (r process). however, the astrophysical site of the r process is a longstanding problem that has captivated both experimental and theoretical a... | neutron star mergers and the r process |
i am reporting on our team's progress in investigating fundamental properties of convective shells in the deep stellar interior during advanced stages of stellar evolution. we have performed a series of 3d hydrodynamic simulations of convection in conditions similar to those in the o-shell burning phase of massive star... | posters also presented at the symposium |
the origin of the elements from roughly zinc-to-tin (30 < z < 50) has yet to be determined. the neutron-rich neutrino driven wind of core collapse supernova (ccsn) is a proposed site for the nucleosynthesis of these elements. however, a significant source of uncertainty exists in elemental abundance yields from a... | development of a neutron long counter detector for (α, n) cross section measurements at ohio university |
radioactivity was discovered as a by-product of searching for elements with suitable chemical properties. understanding its characteristics led to the development of nuclear physics, understanding that unstable configurations of nucleons transform into stable end products through radioactive decay. in the universe, nuc... | astrophysics with radioactive isotopes |
the dominant radioactive energy source powering sn ia light curves is expected to switch from the decay of 56co to 57co at very late epochs. we use archival hubble space telescope images of sn1992a obtained more than 900 days after explosion to constrain its cobalt isotopic abundance ratio and compare it to the well-st... | testing progenitor models using the late-time light curve of supernova 1992a |
narrow-line radio-loud seyfert-1 galaxies are an understudied small class of galaxies that have been identified by their h-beta absorption lines and their emission of synchrotron radiation primarily in the radio (foschini et. al. 2014) (smita et. al. 2012). some of these galaxies have been observed to emit gamma radiat... | a spectroscopic study of radio-loud narrow-line seyfert-1 galaxies |
interactions between material that would become earth's core and mantle began prior to accretion. for example, during and just after the supernova event that is thought to have produced the matter that comprises our solar system, a substantial amount of its iron and other heavy elements were forged in nucleosynthetic p... | alternate histories of the core-mantle boundary region: discrimination by heat flow |
there are numerous reaction rates involving α-particles that play a crucial role in nuclear astrophysics. for instance, some (α,n) reactions have been found to be important for the nucleosynthesis of light nuclei in the rapid neutron-capture process (r-process) in neutrino-driven winds after a core collapse supernovae.... | measuring (α,n) reaction rates relevant for nuclear astrophysics |
radionuclides provide for a unique probe into some of the most interesting phenomena in contemporary astrophysics. the mev gamma-rays emitted by radionuclides allow us to see deep into the objects that house these radioactive isotopes. i will present a high-level overview of astrophysical sites for radionuclides includ... | astrophysical radionuclides: where are they and what can they tell us? |
the fast-expanding neutron-rich neutrino-driven winds in the core-collapse sne is one of the most favorable scenarios for the nucleosynthesis of the z=38-47 elements. charge particle reactions, especially (α,n) on the a=80-90, create seeds for the weak r-process populating abundances of near stable isotopes for the sr-... | measurements of (alpha,n) cross-sections relevant for the weak r-process. |
the meyer and schramm (m&s) independent model formalism is developed to determine the production ratio of actinide chronometers in the nucleosynthesis era of the galaxy formation. the production ratio of u/th is calculated, considering the non-radioactive mass reduction rate of chronometers together with a new prod... | the u/th production ratio from extended independent model |
beta-decay rates for exotic nuclei at n = 126 relevant to r-process nucleosynthesis are studied by shell-model calculations. the half-lives obtained are used to study r-process nucleosynthesis in core-collapse supernova explosions and binary neutron star mergers. the element abundances are obtained up to the third peak... | beta-decay rates for exotic nuclei and r-process nucleosynthesis |
for type ia supernovae, neither the progenitor system nor the details of the explosion mechanism are known. various scenarios are being investigated in the context of different progenitor evolution channels. in the double detonation scenario a sub-chandrasekhar mass carbon-oxygen white dwarf has accreted material from ... | a sub-chandrasekhar mass white dwarf as possible progenitor for a thermonuclear explosion |
nucleosynthesis at the deflagration stage of a white dwarf is considered. burning calculations have been made with the previously developed hydrodynamic model implemented in the front3d code including turbulence. the trajectories of passive particles used thereafter for nucleosynthesis simulations have been created thr... | simulations of burning and nucleosynthesis in a thermonuclear supernova |
stellar explosions such as novae, supernovae, and x-ray bursts involve thermonuclear reactions on rare isotopes. interpretation of observations such as the light curves from x-ray bursts, elemental abundances, or γ-rays from nuclear decay as well as predictions of nucleosynthesis are notably impacted by large uncertain... | measurements of nuclear reactions in stellar explosions with secar |
the p-process is a nucleosynthesis scenario that occurs during an explosion of a supernova and produces the proton-rich isotopes of elements between se and hg. the p-process involves series of (γ,n), (γ,p) and (γ, α) reactions on pre-existing s-process seed nuclei. the reactions relevant for the p-process are studied i... | proton capture studies for the nucleosynthesis p-process using hector |
the project aims to use machine learning algorithms to fit the free parameters of an isotopic scaling model to elemental observations. the processes considered are massive star nucleosynthesis, type ia sne, the s-process, the r-process, and p-isotope production. the analysis on the successful fits seeks to minimize the... | machine learning refinements to metallicity-dependent isotopic abundances |
using the gamma-rays from nucleosynthesis ejecta, supernovae can be 'x-rayed' into their deepest interiors. days after the initial explosion of type ia supernovae, the decay chain of 56ni measured as a function of time can distinguish progenitor models. several years after the explosion, the remnants of probably all su... | gamma-ray observations of supernovae |
type ia supernovae are luminous transients which enrich the interstellar medium with their nucleosynthetic products. they serve as crucial probes for observational cosmology, providing high-precision measurements of both the hubble constant and cosmic acceleration. while multiple scenarios explaining type ia supernovae... | turbulently-driven deflagration-to-detonation transition in near-chandrasekhar mass white dwarfs |
even though sne ia are crucial to cosmological studies as distance indicators, the exact nature of these systems remains theoretically ambiguous and observationally elusive. however, there is a new hope. the very late-time light curves of sne ia harbor important clues to the natures of their progenitor systems. first, ... | the final word: documenting the final days of the nearby type ia supernova 2011fe |
weak-interaction rates, including β-decay and electron captures, are studied in several mass regions at various densities and temperatures of astrophysical interest. in particular, we study odd-a nuclei in the pf-shell region, which are involved in presupernova formations. weak rates are relevant to understand the late... | weak-interaction rates in stellar conditions |
extremely metal-poor (emp) stars ([fe/h] < -3.0) provide fundamental evidence on the nucleosynthesis and enrichment of the first stars and supernovae. lamost will observe 6 million galactic stars through a 5-year spectroscopic survey, and thus provide an unprecedented chance to enlarge the emp star sample. in 2014, ... | exploring the early chemical evolution of the milky way with lamost and subaru |
thermonuclear reaction rate of the 9be formation from two α-particles and a neutron, which is expected to play an important role in supernova nucleosynthesis, is calculated from the cross section of the inverse reaction: the photodisintegration of 9be. numerical calculations of the photodisintegration reaction will be ... | three-body model calculation of 9be formation rate and application to supernova nucleosynthesis |
the neon-sodium (nena) cycle drives the synthesis of the elements between 20ne and 27al, through a series of proton capture reactions that start from 20ne, to end with sodium synthesis. this cycle is active in red giant stars (rgb), asymptotic giant branch stars (agb), in novae as well as in type ia supernovae. in orde... | three new low-energy resonances in the 22ne(p, γ )23na reaction |
tucked away in the deep corners of the universe may lie intermediate-mass black holes: the missing link between supermassive black holes, which sit at the centers of most galaxies, and stellar-mass black holes, which result from supernovae. could white dwarfs help us find these elusive enigmas?tidal tale signs of an in... | searching for intermediate-mass black holes through simulations of tidal disruption events |
planetary nebulae (pne) mark the rapid transition of low- to intermediate-mass stars from the agb to the white-dwarf (wd) cooling sequence. pne provide information on nucleosynthesis, mixing, mass loss, and the relation between a star's initial mass and that of its wd remnant. even the very existence of a pn shows that... | planetary nebulae in star clusters: testing membership with high-precision proper motions |
we explore the nucleosynthesis of carbon using multi-zone galactic chemical evolution models accounting for stellar migration. apogee abundance trends serve as our observational constraint, and our models show excellent agreement with the observed abundance patterns of carbon. we find that our models require the core c... | the galactic chemical evolution of carbon: implications for nucleosynthesis and star formation history |
the first detection of gravitational waves a binary neutron star merger gw170817 by the ligo-virgo collaboration has provided fundamental new insights into the astrophysical site for r-process nucleosynthesis and on the nature of dense neutron-star matter. the detected gravitational wave signal depends upon the tidal d... | constraints on the nuclear equation of state and r-process nucleosynthesis from numerical calculations of the chirp from binary neutron-star merger gw170817 |
star clusters are key observational tools for understanding stellar astrophysics and evolution. determining the abundances of elements resulting from different nucleosynthetic processes such as type i supernovae (producing fe-peak elements, for instance sc, v, cr, mn , fe, co, and ni), winds from evolved stars, core-co... | metallicity and chemical abundances of star clusters in the mw and lmc |
the slow neutron-capture process or s process is responsible for producing about half of the chemical abundances heavier than iron in the solar system. one of the most important nuclear reactions that produce neutrons in stars undergoing the s-process is the 22ne(a,n)25mg reaction. recent studies of this reaction from ... | impact of the new 22ne(a,n)25mg reaction rate on the galactic chemical evolution |
spectroscopy of x-ray and gamma-ray lines is one of the most powerful tools of high-energy astrophysics. in this paper we give an overview of the scientific potential of a high-energy x-ray (1-160kev) imaging telescope using an array of transition-edge sensor microcalorimeters that achieves a spectral resolution (10's ... | high-resolution x-ray and gamma-ray spectroscopy with transition-edge sensors |
nucleosynthesis of iron-group elements in type ia supernovae is studied for single-degenerate models with the use of electron-capture rates updated with the new shell-model hamiltonian in pf -shell. an over-production problem of neutron-rich iron-group isotopes compared with the solar abundances is now found to be supp... | screening effects on electron-capture rates and type ia supernova nucleosynthesis |
the observations of celestial nuclear gamma-rays in the mev energy band provide more understanding of various phenomena such as nucleosynthesis in supernovae and merger of neutron stars. however, the observation in this band is very difficult due to huge background and unclear imaging. the background is created by the ... | smile-ii+ : the 2018 balloon campaign in australia of mev gamma-ray telescope |
in the proto-neutron star formed during a core collapse supernova (ccsn), densities can reach manytimes nuclear density. due to uncertainties in nuclear physics, there are several different physical models for the equation of state (eos) at the densities present in ccsne. the outcomes of ccsn simulations can depend sen... | equation of state dependence of the observable properties of turbulence-aided neutrino-driven core-collapse supernovae |
we propose a unified model for the nucleosynthesis of heavy (a > 57) elements in stars. the neutron flux can be set to describe neutron capture in arbitrary neutron flux. our approach solves the coupled differential equations, that describe the neutron capture and decays of 2696 nuclei, numerically without truncatin... | a unified model for nucleosynthesis of heavy elements in stars |
we have calculated astrophysical reaction cross-sections for (γ,α) reactions of some nuclei important for the calculation of p-process reaction-decay network. reaction rates for α-induced reactions are calculated with the semi-microscopic optical potential constructed using double folding method, where nuclear density ... | importance of α-induced reactions and the inverse (γ,α) process on p-nuclei |
skynet is a general-purpose, open-source nuclear reaction network that is being used for r-process nucleosynthesis calculations in various astrophysical scenarios such as neutron star mergers, accretion disk outflows, and magnetorotationally driven jets in core-collapse supernovae. thanks to a python interface, skynet ... | skynet: an open-source reaction network for r-process nucleosynthesis |
the methodology to estimate element masses in supernova ejecta from nebular spectroscopy is discussed. results using the sumo spectral synthesis code are reviewed with regard to two key elements; oxygen (a hydrostatic burning ash) and nickel (an explosive burning ash). the typical oxygen mass in both type iip and iib s... | determining nucleosynthesis yields in supernovae with spectral modelling |
the type ia supernova remnant (snr) g344.7-0.1 is an extremely important object, since 1) the snr is evolved enough for the reverse shock to have thermalized the entire ejecta and 2) the plasma is still hot enough to emit a strong fe k line. because of this uniqueness, g344.7-0.1 offers an excellent opportunity to inve... | elemental distribution in the evolved type ia snr g344.7-0.1 |
the nucleosynthesis which occurs in core-collapse supernovae (ccsn) is one of the most important sources of elements in the universe. elements from oxygen through iron come predominantly from supernovae, and contributions of heavier elements are also possible through processes like the weak r-process, the gamma process... | nucleosynthesis in core-collapse supernovae |
despite type ia supernovae (sne ia) remaining a benchmark of precision cosmology, a consensus on how and why some white dwarfs explode as sne ia eludes the astronomical community. photometric observations of sne ia at late times measure the conversion efficiency of radioactive decay energy into photons. we request 10 o... | elevating the scientific output of jwst by using hst to examine the heart of type ia supernova 2021aefx |
the origin of the universe's heavy r-process elements is a fundamental issue which affects chemical enrichment across cosmic time and the development of complex life. it is now confirmed that neutron star mergers are responsible for at least some of the r-process budget, but there is gaining observational and theoretic... | identifying a new source of r-process nucleosynthesis with hst |
the roles of nuclear weak processes in stars are discussed. neutrino-nucleus reactions on 12c, 56fe and 40ar are studied with new shell-model hamiltonians. new cross sections, which give good account of experimental data, are applied to nucleosynthesis of light elements in supernova explosions. effects of ν-oscillation... | roles of nuclear weak processes in stars |
spectrum synthesis studies of the uv spectra of sharp-lined main sequence b stars provide astronomers withsome of the best determinations of the abundances of the light, fe group, and neutron capture elements. b stars are therefore best-suited to study the chemical evolution of the magellanic clouds. but the hst archiv... | probing supernovae chemical yields in low metallicity environments with uv spectroscopy of magellanic cloud b-type stars |
this dissertation includes the design and development of the summing nai (sun) 4pi gamma-ray detector at the national superconducting cyclotron laboratory to measure proton and alpha radiative capture reactions relevant in the astrophysical p process. discussions of p-process nucleosynthesis, the relevant nuclear react... | capture cross sections for the astrophysical p process |
the heaviest elements in the periodic table are synthesized through the r-process, but the astrophysical site for r-process nucleosynthesis is still unknown. ultra-faint dwarf galaxies contain a simple fossil record of early chemical enrichment that may determine this site. previous measurements found very low levels o... | a single prolific r-process event preserved in an ultra-faint dwarf galaxy |
the p-process is a nucleosynthesis process that occurs in explosive environments such as type ii and ia supernovae and is responsible for production of heavy proton rich nuclei. gamma rays emitted during these explosions induce several photo-disintegration reactions: (γ,n), (γ,p), and (γ , α). to study these interactio... | efficiency of the high efficiency total absorption spectrometer (hector) |
when a massive star ends its life in a supernova explosion, it can leave behind a tiny, dense remnant called a neutron star. sometimes, two neutron stars end up locked in a gravitational embrace, emitting gravitational waves as they dance toward each other over millions of years. when the pair finally meets, their coll... | featured image: a neutron star collision |
where do the heavy elements the chemical elements beyond iron in our universe come from? one of the primary candidate sources is the merger of two neutron stars, but recent observations have cast doubt on this model. can neutron-star mergers really be responsible?elements from collisions?periodic table showing the orig... | colliding neutron stars as the source of heavy elements |
alma observations of supernova 1987a mixing, nucleosynthesis and dynamics of the ejecta we present a molecular line survey for supernova 1987a, using the atacama large millimetre / submillimetre array (alma). we detected the co, sio, hco+ and so molecular lines from the ejecta. those molecules can probe three different... | alma observations of supernova 1987a mixing, nucleosynthesis and dynamics of the ejecta |
roles of tensor, two-body spin-orbit and three-nucleon forces on nuclear shell evolutions and change of magic numbers in exotic nuclei are discussed. breaking of n = 8 magicity toward the dripline observed in various experimental data as well as appearence of a new magic number n = 6 are well explained with new shell-m... | roles of nuclear forces on the shell evolutions toward driplines |
the nucleosynthetic signatures of the first stars and supernovae are imprinted in the compositions of the most metal-poor stars found today. only a few tens of absorption lines are commonly found in the optical spectra of the second-generation stars, so only 5-10 elements are regularly detected. many others (be, b, si,... | using cetus to study the first stars and first metals |
type ia supernovae are important as sites of nucleosynthesis and as distance indicators. but remarkably, we still do not have a consensus on the underlying progenitor of these events. multimessenger observations over the next decade will bring a wealth of new information about sn ia, allowing us to uncover the origin a... | mma sag: thermonuclear supernovae |
astrophysical reactions involving radioactive isotopes (ri) are of importance for the stellar energy generation and nucleosynthesis especially in high-temperature astrophysical sites, such as x-ray bursts, core-collapse supernovae, and supermassive metalpoor stars. in spite of the essential diffculties in the experimen... | direct measurements and detection techniques with low-energy ribs |
dust is acknowledged to play a variety of important roles in the evolution of galaxies, ranging from regulating molecule formation to determining how metals generated by supernova nucleosynthesis propagate through galaxies. dust has been observed in a wide variety ways as well, though by far most of the observations ha... | the transport and processing of dust in the local interstellar medium |
the 13n(α,p)16o reaction has been recently found to have a significant impact in the estimated yields of 13c during the ingestion of hydrogen into the helium shell of massive stars during the shock propagation of a core-collapse supernovae. the rate of this reaction determines the amount of 13n that can β-decay, produc... | direct measurement of 13n(alpha,p)16o using music |
massive stars, the progenitors of core-collapse supernovae (ccsne), are not well understood, especially as they near core-collapse. modeling multi-wavelength observations that span the photometric and spectroscopic evolution of a supernova allows us to describe the progenitor star (e.g. mass, radius, mass-loss history)... | what can supernovae tell us about massive stars? |
gamma ray lines from cosmic sources reveal the results of nuclear reactions in cosmic sites. following radioactive decays, characteristic lines from excited daughter nuclei can be measured with space-borne gamma ray telescopes which address the mev energy range of the electromagnetic spectrum. high-energy collisions wi... | learning from gamma-ray lines of cosmic radionuclei. |
massive stars end their lives when their core collapses under gravity, resulting in either a core-collapse supernova (successful explosion) or a black hole (failed explosion). despite many efforts, it is not yet fully understood which massive stars will successfully explode in a core-collapse supernova and which ones w... | effects of the nuclear equation of state on the outcome of core-collapse supernovae |
the precise nature of type ia supernovae (sn ia) progenitors remains a mystery, but the detonation of a sub-chandrasekhar-mass white dwarf (wd) has become one of the most promising scenarios. there is a growing body of work suggesting that a carbon core detonation of a sub-chandrasekhar-mass wd can be triggered by the ... | impacts of nuclear reaction rate uncertainties on nucleosynthesis in sub-chandrasekhar-mass white dwarf detonations |
we present new ultra-metal-poor stars parameters with [fe/h] < -4.0 based on line-by-line non-local thermodynamic equilibrium (nlte) abundances using an up-to-date iron model atom with a new recipe for non-elastic hydrogen collision rates. we study the departures from lte in their atmospheric parameters and show tha... | vizier online data catalog: ultra-metal-poor stars lte and nlte abundances (ezzeddine+, 2017) |
the observation of a kilonova (at 2017gfo) associated with the gravitational-wave source gw170817 in the summer of 2017 provided direct evidence that r-process matter is synthetized in binary neutron-star mergers. whereas this site is likely the main host for the main r process, responsible for the robustness of the ab... | nucleosynthesis of ``light r elements'' in neutrino-drive winds. role of (α,n) reaction rates. |
type ia supernovae (sne ia) are the thermonuclear incineration of white dwarfs, which are the evolutionary terminus of low-mass stars; these supernovae are a primary source of iron in the universe and the premier distance indicator for cosmological studies. current and future observational surveys are uncovering tantal... | the nuclear physics of type ia supernovae |
60fe is created in massive stars prior to core collapse supernova. the signature γ-rays from β-decay of this isotope indicate ongoing nucleosynthesis in the galaxy among other interesting astrophysical processes. in order to understand these observations a complete understanding of the creation, destruction and nuclear... | nucleosynthesis of 60fe and constraints on the nuclear level density and photon strength function |
recent observational advances have enabled high resolution mapping of 44ti in core-collapse supernova (ccsn) remnants. comparisons between observations and 3d models provide stringent constraints on the ccsn mechanism. however, recent work has identified several uncertain nuclear reaction rates that influence 44ti and ... | reaction rates that limit 44ti from core-collapse supernovae as dense matter constraint: shocking results |
massive stars at the end of their lifetimes undergo gravitational collapse and explode vigorously as core-collapse supernovae (ccsne), enriching the interstellar medium and sourcing many of the heavy elements in the universe. in addition to hosting nucleosynthesis, these explosions revitalize ambient star formation, bi... | revival of the fittest: exploding core-collapse supernovae |
multi-physics simulations of stellar explosions (such as supernovae and neutron star mergers) are one of the most important avenues available to address fundamental questions in nuclear astrophysics, such as the cosmic origin of the elements, the behavior of matter and neutrinos at extreme densities, the structure and ... | nuclear astrophysics approaching the exascale: multi-physics simulations of stellar explosions and their nucleosynthesis |
in neutron-rich winds from core-collapse supernovae, heavy elements are synthesized by the alpha process, in particular (α ,n) reactions. almost all (α ,n) reaction rates involved in the alpha process are calculated with statistical models. the predictive power of these models is uncertain, especially away from the val... | impact of (α , n) reaction rate uncertainties on the nucleosynthesis in neutrino-driven winds |
chlorine is an odd-z, light element that has been poorly studied in stars. recently, the first stellar abundance measurements of the isotopologue 35cl were made and the 35cl/37cl ratio was derived in rz ari (maas et al. 2016). additional abundance measurements are necessary to understand the galactic chemical evolution... | chlorine isotope ratios in m giants and s stars |
r coronae borealis (rcb) stars form a small class of cool, carbon-rich supergiants that have almost no hydrogen. they undergo extreme, irregular declines in brightness of up to 8 magnitudes due to the formation of thick clouds of carbon dust. two scenarios have been proposed for the origin of an rcb star: the merger of... | evolving r coronae borealis stars with mesa |
an overview of recent research done on the 2 mj, 192 beam nif laser facility at llnl through the nif discovery science program will be presented. a selection of examples will be drawn from experiments on nuclear reactions in capsule implosions relevant to stellar nucleosynthesis [1]; studies of equations of state and p... | exploring the universe through discovery science on nif |
gamow-teller strengths in pf-shell nuclei obtained by a new shell-model hamltonian, gxpf1j, are used to evaluate electron-capture rates in pf-shell nuclei at stellar environments. the nuclear weak rates with gxpf1j, which are generally smaller than previous evaluations for proton-rich nuclei, are applied to nucleosynth... | electron-capture rates for pf-shell nuclei in stellar environments and nucleosynthesis |
cemp-no stars are iron-deficient, carbon-rich stars, with no or little s- and r-elements. because of their very low iron content, they are often considered to be closely linked to the first stars. their origin is still a matter of debate. understanding their formation could provide very valuable information on the firs... | toward the first stars: hints from the cemp-no stars |
since clusters of galaxies are the largest comprehensive samples of the universe, they provide essential information on from the most basic to the most complex physical mechanisms such as nucleosynthesis and supernovae events. some of these information are provided by the x-ray emission data from intra cluster medium (... | radial profiles of pks 0745-191 galaxy cluster with xmm-newton x-ray observations |
nuclear structure and composition in ultra-strong magnetic fields relevant for heavy-ion collisions, supernovae, andmagnetar crusts are analyzed. for field intensities exceeding 0.1 teratesla (tt) nuclear magnetic response is represented as combined reactivity of valent outer-shell nucleons, exhibits linear regime up t... | zeeman effect at explosive nuclide formation |
the rapid neutron capture process (r-process) is believe to synthesize the heaviest elements found on the periodic table. this remarkable process is believed to occur in exotic environments such as compact object mergers and possibly supernovae. in the most neutron-rich components of explosive outflows, nuclear fission... | macroscopic-microscopic fission yields for nucleosynthesis |
the neutrino-nucleus interactions are important for understanding nucleosyntheses by neutrino-induced reactions as well as supernova explosion mechanisms. the m1 strength in atomic nuclei is important for estimation of neutrino-nucleus interactions. we studied neutron angular distribution from (γ, n) reactions with lin... | m1 strength in photonuclear reactions with linearly polarized γ-ray beam |
supernovae are a major source of the chemical elements in galaxies and the universe. they are not only the site of nucleosynthetic processes, but they also deliver their products to the interstellar medium together with energy and momentum. the mechanical input from the supernova explosions can generate outflows of gas... | supernovae and the chemical evolution of galaxies |
recent experiments show that gamow-teller (gt) strengths for pf-shell nuclei are overestimated in conventional shell models. however, a state-of-the-art shell model successfully reproduces the reduced gt strengths. in this study, we perform nuclear network calculations for type ia supernovae nucleosynthesis with the ne... | impact of new gamow-teller strengths on explosive type ia supernova nucleosynthesis |
we investigate nucleosynthesis in core-collapse supernovae (sne) of massive stars of 10.8-40m ⊙ , based on 2d hydrodynamic simulations of the sn explosion. we follow long-term evolution of the explosion over 1 s after the core bounce, adopting a neutrino-core model, with which we evaluate the evolution of neutrino lumi... | nucleosynthesis in asymmetric, core-collapse supernovae of massive stars |
neutron-rich neutrino driven winds in core-collapse supernovae have been proposed as a possible site for the nucleosynthesis of the relatively high z =38-47 abundances observed in some metal-poor stars. in this scenario, (a,xn) reactions are the main production mechanism of heavier nuclei once the temperature has decre... | development, commissioning and first experiment of the habanero detector for the measurement of astrophysically important (a,n) reaction rates |
the production and ejection of radioactive isotopes during, or immediately following, the merger of two neutron stars (or a neutron star and a black hole) can give rise to optical/infrared emission similar to, but dimmer and briefer than that of an ordinary supernova. these transients are promising electromagnetic coun... | optical transients and nucleosynthesis from neutron star mergers |
super asymptotic giant branch (super-agb) stars reside in the mass range ~ 6.5-10 m⊙ and bridge the divide between low/intermediate-mass and massive stars. they are characterised by off-centre carbon ignition prior to a thermally pulsing phase which can consist of many tens to even thousands of thermal pulses. with the... | hiding in plain sight - red supergiant imposters? super-agb stars - bridging the divide between low/intermediate-mass and high-mass stars |
extremely metal-poor (emp) stars ([fe/h] < -3.0) are believed to form at the earliest stage of the galactic chemical evolution. emp stars are rare, but provide basic information of first stars and supernova, as well as on the nucleosynthesis and chemical enrichment of the very beginning of the universe. lamost (larg... | searching for chemical relics of first stars with lamost and subaru |
since the discovery of pulsars in 1967, few celestial phenomena have fascinated amateur and professional astronomers, and the public, more than supernovae - dying stars that explode spectacularly and, in so doing, may outshine a whole galaxy. thousands of research papers, reviews, monographs and books have been publish... | handbook of supernovae |
recent observational advances have enabled high resolution mapping of ti-44 in core-collapse supernova (ccsn) remnants. comparisons between observations and 3d models provide stringent constraints on the ccsn mechanism. however, recent work has identified several uncertain nuclear reaction rates that influence ti-44 an... | investigating the impact of reaction rate uncertainties on ti-44 and ni-56 production in shock driven nucleosynthesis of core-collapse supernovae |
the experimental opportunities offered by radioactive ion-beam (rib) facilities and the advances in nuclear modeling, together with significant progress in astrophysical models and astronomical observations, have led to impressive advances in our understanding of exotic astrophysical objects like supernovae or neutron-... | progress and challenges in nuclear astrophysics |
astrophysical site(s) of rapid neutron-capture process (r-process) is (are) not identified yet. although core-collapse supernovae have been regarded as one of the possible candidates of the astrophysical site of r-process, nucleosynthesis studies suggest that serious difficulties in core-collapse supernovae to produce ... | astrophysical site(s) of r-process elements in galactic chemodynamical evolution model |
we have measured the abundance of 60fe, a radioactive isotope in cosmic rays that serves as a clock to infer an upper limit on the time between nucleosynthesis in supernovae and cosmic ray acceleration. the ace-cris instrument has collected 3.55 ×105 iron nuclei from which we have resolved 15 60fe nuclei. from this a 6... | observation of the 60fe nucleosynthesis-clock isotope in galactic cosmic rays |
neutrons produced by the carbon fusion reaction 12c(12c,n)23mg play an important role in stellar nucleosynthesis. past studies have shown large discrepancies between experimental data and theory, leading to an uncertain cross section extrapolation at astrophysical energies. we present the first direct measurement which... | first direct measurement of 12c(12c,n)23mg at stellar energies |
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