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ssmann świątecki szilárd teller thomson walton wigner physics portal category v t e nuclear astrophysics studies the origin of the chemical elements and isotopes and the role of nuclear energy generation in cosmic sources such as stars supernovae novae and violent binary star interactions it is an interdisciplinary part of both nuclear physics and astrophysics involving close collaboration among researchers in various subfields of each of these fields this includes notably nuclear reactions and their rates as they occur in cosmic environments and modeling of astrophysical objects where these nuclear reactions may occur but also considerations of cosmic evolution of isotopic and elemental composition often called chemical evolution constraints from observations involve multiple messengers all across the electromagnetic spectrum nuclear gamma rays x rays optical and radio sub mm astronomy as well as isotopic measurements of solar system materials such as meteorites and their stardust inclusions cosmic rays material deposits on the earth and moon nuclear physics experiments address stability i e lifetimes and masses for atomic nuclei well beyond the regime of stable nuclides into the realm of radioactive unstable nuclei almost to the limits of bound nuclei the drip lines and under high density up to neutron star matter and high temperature plasma temperatures up to 10 9 k theories and simulations are essential parts herein as cosmic nuclear reaction environments cannot be realized but at best partially approximated by experiments history edit in the 1940s geologist hans suess speculated that the regularity that was observed in the abundances of elements may be related to structural properties of the atomic nucleus 1 these considerations were seeded by the discovery of radioactivity by becquerel in 1896 2 as an aside of advances in chemistry which aimed at production of gold this remarkable possibility for transformation of matter created much excitement among physicists for the next decades culminating in discovery of the atomic nucleus with milestones in ernest rutherford s scattering experiments in 1911 and the discovery of the neutron by james chadwick 1932 after aston demonstrated that the mass of helium is less than four times that of the proton eddington proposed that through an unknown process in the sun s core hydrogen is transmuted into helium liberating energy 3 twenty years later bethe and von weizsäcker independently derived the cn cycle 4 5 the first known nuclear reaction that accomplishes this transmutation the interval between eddington s proposal and derivation of the cn cycle can mainly be attributed to an incomplete understanding of nuclear structure the basic principles for explaining the origin of elements and energy generation in stars appear in the concepts describing nucleosynthesis which arose in the 1940s led by george gamow and presented in a 2 page paper in 1948 as the alpher bethe gamow paper a complete concept of processes that make up cosmic nucleosynthesis was presented in the late 1950s by burbidge burbidge fowler and hoyle 6 and by cameron 7 fowler is largely credited with initiating collaboration between astronomers astrophysicists and theoretical and experimental nuclear physicists in a field that we now know as nuclear astrophysics 8 for which he won the 1983 nobel prize during these same decades arthur eddington and others were able to link the liberation of nuclear binding energy through such nuclear reactions to the structural equations of stars 9 these developments were not without curious deviations many notable physicists of the 19th century such as mayer waterson von helmholtz and lord kelvin postulated that the sun radiates thermal energy by converting gravitational potential energy into heat its lifetime as calculated from this assumption using the virial theorem around 19 million years was found inconsistent with the interpretation of geological records and the then new theory of biological evolution alternatively if the sun consisted entirely of a fossil fuel like coal considering the rate of its thermal energy emission its lifetime would be merely four or five thousand years clearly inconsistent with records of human civilization basic concepts edit this section does not cite any sources please help improve this section by adding citations to reliable sources unsourced material may be challenged and removed march 2020 learn how and when to remove this message during cosmic times nuclear reactions re arrange the nucleons that were left behind from the big bang in the form of isotopes of hydrogen and helium and traces of lithium beryllium and boron to other isotopes and elements as we find them today see graph 10 the driver is a conversion of nuclear binding energy to exothermic energy favoring nuclei with more binding of their nucleons these are then lighter as their original components by the binding energy the most tightly bound nucleus from symmetric matter of neutrons and protons is 56 ni 11 the release of nuclear binding energy is what allows stars to shine for up to billions of years and may disrupt stars in stellar explosions in case of violent reactions such as 12 c 12 c fusion for thermonuclear supernova explosions as matter is processed as such within stars and stellar explosions some of the products are ejected from the nuclear reaction site and end up in interstellar gas then it may form new stars and be processed further through nuclear reactions in a cycle of matter this results in compositional evolution of cosmic gas in and between stars and galaxies enriching such gas with heavier elements nuclear astrophysics is the science to describe and understand the nuclear and astrophysical processes within such cosmic and galactic chemical evolution linking it to knowledge from nuclear physics and astrophysics measurements are used to test our understanding astronomical constraints are obtained from stellar and interstellar abundance data of elements and isotopes and other multi messenger astronomical measurements of the cosmic object phenomena help to understand and model these nuclear properties can be obtained from terrestrial nuclear laboratories such as accelerators with their experiments theory and simulations are needed to understand and complement such data providing models for nuclear reaction rates under the variety of cosmic conditions and for the structure and dynamics of cosmic objects findings current status and issues edit nuclear astrophysics remains as a complex puzzle to science 12 the current consensus on the origins of elements and isotopes are that only hydrogen and helium and traces of lithium can be formed in a homogeneous big bang see big bang nucleosynthesis while all other elements and their isotopes are formed in cosmic objects that formed later such as in stars and their explosions 13 the sun s primary energy source is hydrogen fusion to helium at about 15 million degrees the proton proton chain reactions dominate they occur at much lower energies although much more slowly than catalytic hydrogen fusion through cno cycle reactions nuclear astrophysics gives a picture of the sun s energy source producing a lifetime consistent with the age of the solar system derived from meteoritic abundances of lead and uranium isotopes an age of about 4 5 billion years the core hydrogen burning of stars as it now occurs in the sun defines the main sequence of stars illustrated in the hertzsprung russell diagram that classifies stages of stellar evolution the sun s lifetime of h burning via pp chains is about 9 billion years this primarily is determined by extremely slow production of deuterium 1 1 h 1 1 h 2 1 d e ν e 0 42 mev which is governed by the weak interaction work that led to discovery of neutrino oscillation implying a non zero mass for the neutrino absent in the standard model of particle physics was motivated by a solar neutrino flux about three times lower than expected from theories a long standing concern in the nuclear astrophysics community colloquially known as the solar neutrino problem the concepts of nuclear astrophysics are supported by observation of the element technetium the lightest chemical element without stable isotopes in stars 14 by galactic gamma ray line emitters such as 26 al 15 60 fe and 44 ti 16 by radioactive decay gamma ray lines from the 56 ni decay chain observed from two supernovae sn1987a and sn2014j coincident with optical supernova light and by observation of neutrinos from the sun 17 and from supernova 1987a these observations have far reaching implications 26 al has a lifetime of a million years which is very short on a galactic timescale proving that nucleosynthesis is an ongoing process within our milky way galaxy in the current epoch abundances of the chemical elements in the solar system hydrogen and helium are most common the next three elements li be b are rare intermediate mass elements such as c o si ca more abundant beyond fe there is a remarkable drop beyond fe heavier elements being 3 5 orders of magnitude less abundant the two general trends in the remaining stellar produced elements are 1 an alternation of abundance of elements according to whether they have even or odd atomic numbers and 2 a general decrease in abundance as elements become heavier 13 within this trend is a peak at abundances of iron and nickel and smaller peaks at elements whose beta stable isotopes are located near neutron magic numbers current descriptions of the cosmic evolution of elemental abundances are broadly consistent with those observed in the solar system and galaxy 13 the roles of specific cosmic objects in producing these elemental abundances are clear for some elements and heavily debated for others for example iron is believed to originate mostly from thermonuclear supernova explosions also called supernovae of type ia and carbon and oxygen is believed to originate mostly from massive stars and their explosions lithium beryllium and boron are believed to originate from spallation reactions of cosmic ray nuclei such as carbon and heavier nuclei breaking these apart 13 elements heavier than nickel are produced via the slow and rapid neutron capture processes each contributing roughly half the abundance of these elements 18 the s process is believed to occur in the envelopes of dying stars whereas some uncertainty exists regarding r process sites the r process is believed to occur in supernova explosions and compact object mergers though observational evidence is limited to a single event gw170817 and relative yields of proposed r process sites leading to observed heavy element abundances are uncertain 13 18 19 the transport of nuclear reaction products from their sources through the interstellar and intergalactic medium also is unclear additionally many nuclei that are involved in cosmic nuclear reactions are unstable and may only exist temporarily in cosmic sites and their properties e g binding energy cannot be investigated in the laboratory due to difficulties in their synthesis similarly stellar structure and its dynamics is not satisfactorily described in models and hard to observe except through asteroseismology and supernova explosion models lack a consistent description based on physical processes and include heuristic elements current research extensively utilizes computation and numerical modeling 20 future work edit although the foundations of nuclear astrophysics appear clear and plausible many puzzles remain these include understanding helium fusion specifically the 12 c α γ 16 o reaction s 21 astrophysical sites of the r process 18 anomalous lithium abundances in population ii stars 22 the explosion mechanism in core collapse supernovae 20 and progenitors of thermonuclear supernovae 23 see also edit nuclear physics astrophysics nucleosynthesis abundance of the chemical elements joint institute for nuclear astrophysics references edit suess hans e urey harold c 1956 abundances of the elements reviews of modern physics 28 1 53 bibcode 1956rvmp 28 53s doi 10 1103 revmodphys 28 53 henri becquerel 1896 sur les radiations émises par phosphorescence comptes rendus 122 420 421 see also a translation by carmen giunta eddington a s 1919 the sources of stellar energy the observatory 42 371 376 bibcode 1919obs 42 371e von weizsäcker c f 1938 über elementumwandlungen in innern der sterne ii element transformation inside stars ii physikalische zeitschrift 39 633 646 bethe h a 1939 energy production in stars physical review 55 5 434 56 bibcode 1939phrv 55 434b doi 10 1103 physrev 55 434 e m burbidge g r burbidge w a fowler f hoyle 1957 synthesis of the elements in stars pdf reviews of modern physics 29 4 547 bibcode 1957rvmp 29 547b doi 10 1103 revmodphys 29 547 cameron a g w 1957 stellar evolution nuclear astrophysics and nucleogenesis pdf report atomic energy of canada barnes c a clayton d d schramm d n eds 1982 essays in nuclear astrophysics cambridge university press isbn 978 0 52128 876 7 a s eddington 1940 the physics of white dwarf stars monthly notices of the royal astronomical society 100 582 bibcode 1940mnras 100 582e doi 10 1093 mnras 100 8 582 24 big bang nucleosynthesis pdf particle data group 2023 retrieved november 17 2025 shigehiro nagataki masa aki hashimoto shoichi yamada february 1998 initial shock waves for explosive nucleosynthesis in type ii supernova publications of the astronomical society of japan 50 67 arxiv astro ph 9807014 bibcode 1998pasj 50 67n doi 10 1093 pasj 50 1 67 issn 0004 6264 archived from the original on 2020 11 29 j josé c iliadis 2011 nuclear astrophysics the unfinished quest for the origin of the elements reports on progress in physics 74 9 6901 arxiv 1107 2234 bibcode 2011rpph 74i6901j doi 10 1088 0034 4885 74 9 096901 s2cid 118505733 1 2 3 4 5 johnson j a fields b d thompson t a 2020 the origin of the elements a century of progress philosophical transactions of the royal society a 378 20190301 bibcode 2020rspta 37890301j doi 10 1098 rsta 2019 0301 pmid 32811358 p w merrill 1956 technetium in the n type star 19 piscium publications of the astronomical society of the pacific 68 400 400 bibcode 1956pasp 68 70m doi 10 1086 126883 diehl r et al 1995 comptel observations of galactic 26 al emission astronomy and astrophysics 298 445 bibcode 1995a a 298 445d iyudin a f et al 1994 comptel observations of ti 44 gamma ray line emission from cas a astronomy and astrophysics 294 l1 bibcode 1994a a 284l 1i davis raymond harmer don s hoffman kenneth c 1968 search for neutrinos from the sun physical review letters 20 21 1205 bibcode 1968phrvl 20 1205d doi 10 1103 physrevlett 20 1205 1 2 3 martínez pinedo g langanke k 2023 nuclear quests for the r process the european physical journal a 59 67 67 bibcode 2023epja 59 67m doi 10 1140 epja s10050 023 00987 9 rosswog s korobkin o 2022 heavy elements and electromagnetic transients from neutron star mergers annalen der physik 536 2200306 22...