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Stellar nucleosynthesis is the creation (nucleosynthesis) of chemical elements by nuclear fusion reactions within stars. Stellar nucleosynthesis has occurred since the original creation of hydrogen, helium and lithium during the Big Bang. As a predictive theory, it yields accurate estimates of the observed abundances of the elements. It explains why the observed abundances of elements change over time and why some elements and their isotopes are much more abundant than others. The theory was initially proposed by Fred Hoyle in 1946,[1] who later refined it in 1954.[2] Further advances were made, especially to nucleosynthesis by neutron capture of the elements heavier than iron, by Margaret and Geoffrey Burbidge, William Alfred Fowler and Hoyle in their famous 1957 B2FH paper,[3] which became one of the most heavily cited papers in astrophysics history.

Stars evolve because of changes in their composition (the abundance of their constituent elements) over their lifespans, first by burning hydrogen (main sequence star), then helium (red giant star), and progressively burning higher elements. However, this does not by itself significantly alter the abundances of elements in the universe as the elements are contained within the star. Later in its life, a low-mass star will slowly eject its atmosphere via stellar wind, forming a planetary nebula, while a higher–mass star will eject mass via a sudden catastrophic event called a supernova. The term supernova nucleosynthesis is used to describe the creation of elements during the explosion of a massive star or white dwarf.

The advanced sequence of burning fuels is driven by gravitational collapse and its associated heating, resulting in the subsequent burning of carbon, oxygen and silicon. However, most of the nucleosynthesis in the mass range A = 28–56 (from silicon to nickel) is actually caused by the upper layers of the star collapsing onto the core, creating a compressional shock wave rebounding outward. The shock front briefly raises temperatures by roughly 50%, thereby causing furious burning for about a second. This final burning in massive stars, called explosive nucleosynthesis or supernova nucleosynthesis, is the final epoch of stellar nucleosynthesis.

A stimulus to the development of the theory of nucleosynthesis was the discovery of variations in the abundances of elements found in the universe. The need for a physical description was already inspired by the relative abundances of isotopes of the chemical elements in the solar system. Those abundances, when plotted on a graph as a function of atomic number of the element, have a jagged sawtooth shape that varies by factors of tens of millions (see history of nucleosynthesis theory).[4] This suggested a natural process that is not random. A second stimulus to understanding the processes of stellar nucleosynthesis occurred during the 20th century, when it was realized that the energy released from nuclear fusion reactions accounted for the longevity of the Sun as a source of heat and light.[5]

History
In 1920, Arthur Eddington proposed that stars obtained their energy from nuclear fusion of hydrogen to form helium and also raised the possibility that the heavier elements are produced in stars.

In 1920, Arthur Eddington, on the basis of the precise measurements of atomic masses by F.W. Aston and a preliminary suggestion by Jean Perrin, proposed that stars obtained their energy from nuclear fusion of hydrogen to form helium and raised the possibility that the heavier elements are produced in stars.[6][7][8] This was a preliminary step toward the idea of stellar nucleosynthesis. In 1928, George Gamow derived what is now called the Gamow factor, a quantum-mechanical formula that gave the probability of bringing two nuclei sufficiently close for the strong nuclear force to overcome the Coulomb barrier.[9]:410 The Gamow factor was used in the decade that followed by Atkinson and Houtermans and later by Gamow himself and Edward Teller to derive the rate at which nuclear reactions would occur at the high temperatures believed to exist in stellar interiors.

In 1939, in a paper entitled "Energy Production in Stars", Hans Bethe analyzed the different possibilities for reactions by which hydrogen is fused into helium.[10] He defined two processes that he believed to be the sources of energy in stars. The first one, the proton–proton chain reaction, is the dominant energy source in stars with masses up to about the mass of the Sun. The second process, the carbon–nitrogen–oxygen cycle, which was also considered by Carl Friedrich von Weizsäcker in 1938, is more important in more massive main-sequence stars.[11]:167 These works concerned the energy generation capable of keeping stars hot. A clear physical description of the proton–proton chain and of the CNO cycle appears in a 1968 textbook.[5] Bethe's two papers did not address the creation of heavier nuclei, however. That theory was begun by Fred Hoyle in 1946 with his argument that a collection of very hot nuclei would assemble thermodynamically into iron[1] Hoyle followed that in 1954 with a paper describing how advanced fusion stages within massive stars would synthesize the elements from carbon to iron in mass.[2][12]

Hoyle's theory was expanded to other processes, beginning with the publication of a review paper in 1957 by Burbidge, Burbidge, Fowler and Hoyle (commonly referred to as the B2FH paper).[3] This review paper collected and refined earlier research into a heavily cited picture that gave promise of accounting for the observed relative abundances of the elements; but it did not itself enlarge Hoyle's 1954 picture for the origin of primary nuclei as much as many assumed, except in the understanding of nucleosynthesis of those elements heavier than iron by neutron capture. Significant improvements were made by Alastair G. W. Cameron and by Donald D. Clayton. Cameron presented his own independent approach in 1957[13] (following Hoyle's approach for the most part) of nucleosynthesis. He introduced computers into time-dependent calculations of evolution of nuclear systems. Clayton calculated the first time-dependent models of the s-process in 1961[14] and of the r-process in 1965,[15] as well as of the burning of silicon into the abundant alpha-particle nuclei and iron-group elements in 1968,[16][17] and discovered radiogenic chronologies[18] for determining the age of the elements.

The entire research field expanded rapidly in the 1970s.
Cross section of a supergiant showing nucleosynthesis and elements formed.
Key reactions
A version of the periodic table indicating the origins – including stellar nucleosynthesis – of the elements. Elements above 94 are manmade and are not included.

The most important reactions in stellar nucleosynthesis:

Hydrogen fusion:
Deuterium fusion
The proton–proton chain
The carbon–nitrogen–oxygen cycle
Helium fusion:
The triple-alpha process
The alpha process
Fusion of heavier elements:
Lithium burning: a process found most commonly in brown dwarfs
Carbon-burning process
Neon-burning process
Oxygen-burning process
Silicon-burning process
Production of elements heavier than iron:
Neutron capture:
The r-process
The s-process
Proton capture:
The rp-process
The p-process
Photodisintegration

Hydrogen fusion
Main articles: Proton–proton chain reaction, CNO cycle, and Deuterium fusion
Proton–proton chain reaction
CNO-I cycle
The helium nucleus is released at the top-left step.

Hydrogen fusion (nuclear fusion of four protons to form a helium-4 nucleus[19]) is the dominant process that generates energy in the cores of main-sequence stars. It is also called "hydrogen burning", which should not be confused with the chemical combustion of hydrogen in an oxidizing atmosphere. There are two predominant processes by which stellar hydrogen fusion occurs: proton-proton chain and the carbon-nitrogen-oxygen (CNO) cycle. Ninety percent of all stars, with the exception of white dwarfs, are fusing hydrogen by these two processes.

In the cores of lower-mass main-sequence stars such as the Sun, the dominant energy production process is the proton–proton chain reaction. This creates a helium-4 nucleus through a sequence of reactions that begin with the fusion of two protons to form a deuterium nucleus (one proton plus one neutron) along with an ejected positron and neutrino.[20] In each complete fusion cycle, the proton–proton chain reaction releases about 26.2 MeV.[20] The proton–proton chain reaction cycle is relatively insensitive to temperature; a 10% rise of temperature would increase energy production by this method by 46%, hence, this hydrogen fusion process can occur in up to a third of the star's radius and occupy half the star's mass. For stars above 35% of the Sun's mass,[21] the energy flux toward the surface is sufficiently low and energy transfer from the core region remains by radiative heat transfer, rather than by convective heat transfer.[22] As a result, there is little mixing of fresh hydrogen into the core or fusion products outward.

In higher-mass stars, the dominant energy production process is the CNO cycle, which is a catalytic cycle that uses nuclei of carbon, nitrogen and oxygen as intermediaries and in the end produces a helium nucleus as with the proton-proton chain.[20] During a complete CNO cycle, 25.0 MeV of energy is released. The difference in energy production of this cycle, compared to the proton–proton chain reaction, is accounted for by the energy lost through neutrino emission.[20] The CNO cycle is very temperature sensitive, a 10% rise of temperature would produce a 350% rise in energy production. About 90% of the CNO cycle energy generation occurs within the inner 15% of the star's mass, hence it is strongly concentrated at the core.[23] This results in such an intense outward energy flux that convective energy transfer become more important than does radiative transfer. As a result, the core region becomes a convection zone, which stirs the hydrogen fusion region and keeps it well mixed with the surrounding proton-rich region.[24] This core convection occurs in stars where the CNO cycle contributes more than 20% of the total energy. As the star ages and the core temperature increases, the region occupied by the convection zone slowly shrinks from 20% of the mass down to the inner 8% of the mass.[23] Our Sun produces on the order of 1% of its energy from the CNO cycle.[25]:357[26][27]

The type of hydrogen fusion process that dominates in a star is determined by the temperature dependency differences between the two reactions. The proton–proton chain reaction starts at temperatures about 4×106 K,[28] making it the dominant fusion mechanism in smaller stars. A self-maintaining CNO chain requires a higher temperature of approximately 16×106 K, but thereafter it increases more rapidly in efficiency as the temperature rises, than does the proton-proton reaction.[29] Above approximately 17×106 K, the CNO cycle becomes the dominant source of energy. This temperature is achieved in the cores of main sequence stars with at least 1.3 times the mass of the Sun.[30] The Sun itself has a core temperature of about 15.7×106 K. As a main sequence star ages, the core temperature will rise, resulting in a steadily increasing contribution from its CNO cycle.[23]
Helium fusion
Main articles: Triple-alpha process and Alpha process

Main sequence stars accumulate helium in their cores as a result of hydrogen fusion, but the core does not become hot enough to initiate helium fusion. Helium fusion first begins when a star leaves the red giant branch after accumulating sufficient helium in its core to ignite it. In stars around the mass of the sun, this begins at the tip of the red giant branch with a helium flash from a degenerate helium core, and the star moves to the horizontal branch where it burns helium in its core. More massive stars ignite helium in their core without a flash and execute a blue loop before reaching the asymptotic giant branch. Such a star initially moves away from the AGB toward bluer colors, then loops back again to what is called the Hayashi track. An important consequence of blue loops is that they give rise to classical Cepheid variables, of central importance in determining distances in the Milky Way and to nearby galaxies.[31]:250 Despite the name, stars on a blue loop from the red giant branch are typically not blue in color, but are rather yellow giants, possibly Cepheid variables. They fuse helium until the core is largely carbon and oxygen. The most massive stars become supergiants when they leave the main sequence and quickly start helium fusion as they become red supergiants. After helium is exhausted in the core of a star, it will continue in a shell around the carbon-oxygen core.[19][22]

In all cases, helium is fused to carbon via the triple-alpha process, i.e., three helium nuclei are transformed into carbon via 8Be.[32]:30 This can then form oxygen, neon, and heavier elements via the alpha process. In this way, the alpha process preferentially produces elements with even numbers of protons by the capture of helium nuclei. Elements with odd numbers of protons are formed by other fusion pathways.
Reaction rate

The reaction rate density between species A and B, having number densities nA,B is given by:

\( {\displaystyle r=n_{A}\,n_{B}\,k} \)

where k is the reaction rate constant of each single elementary binary reaction composing the nuclear fusion process:

\( {\displaystyle k=\langle \sigma (v)\,v\rangle } \)

here, σ(v) is the cross section at relative velocity v, and averaging is performed over all velocities.

Semi-classically, the cross section is proportional to \( {\displaystyle \pi \,\lambda ^{2}} \), where \( {\displaystyle \lambda =h/p} \) is the de Broglie wavelength. Thus semi-classically the cross section is proportional to \( {\displaystyle {\frac {m}{E}}}. \)

However, since the reaction involves quantum tunneling, there is an exponential damping at low energies that depends on Gamow factor EG, giving an Arrhenius equation:

\( {\displaystyle \sigma (E)={\frac {S(E)}{E}}e^{-{\sqrt {\frac {E_{G}}{E}}}}} \)

where S(E) depends on the details of the nuclear interaction, and has the dimension of an energy multiplied for a cross section.

One then integrates over all energies to get the total reaction rate, using the Maxwell–Boltzmann distribution and the relation :

\( {\displaystyle {\frac {r}{V}}=n_{A}\,n_{B}\int _{0}^{\infty }{\frac {S(E)}{E}}\,e^{-{\sqrt {\frac {E_{G}}{E}}}}{\frac {2}{{\sqrt {\pi }}(kT)^{3/2}}}E^{1/2}e^{-E/kT}\,{\sqrt {\frac {2E}{m_{R}}}}dE} \)

where \( {\displaystyle m_{R}={\frac {m_{1}m_{2}}{m_{1}+m_{2}}}} \) is the reduced mass.

Since this integration has an exponential damping at high energies of the form \( {\displaystyle \sim e^{-{\frac {E}{kT}}}} \) and at low energies from the Gamow factor, the integral almost vanished everywhere except around the peak, called Gamow peak,[33]:185 at E0, where:

\( {\displaystyle {\frac {\partial }{\partial E}}\left(-{\sqrt {\frac {E_{G}}{E}}}-{\frac {E}{kT}}\right)\,=\,0} \)

Thus:

\( {\displaystyle E_{0}=\left({\sqrt {E_{G}}}\,kT/2\right)^{2/3}} \)

The exponent can then be approximated around E0 as:

\( {\displaystyle e^{-{\frac {E}{kT}}-{\sqrt {\frac {E_{G}}{E}}}}\approx e^{-{\frac {3E_{0}}{kT}}}\cdot \exp \left(-{\frac {(E-E_{0})^{2}}{4E_{0}kT/3}}\right)} \)

And the reaction rate is approximated as:[34]

\( {\displaystyle {\frac {r}{V}}\approx n_{A}\,n_{B}\,{\frac {4{\sqrt {2}}}{\sqrt {3m_{R}}}}\,{\sqrt {E_{0}}}{\frac {S(E_{0})}{kT}}e^{-{\frac {3E_{0}}{kT}}}} \)

Values of S(E0) are typically 10^−3-10^3 keV*b, but are damped by a huge factor when involving a beta decay, due to the relation between the intermediate bound state (e.g. diproton) half-life and the beta decay half-life, as in the proton–proton chain reaction. Note that typical core temperatures in main-sequence stars give kT of the order of keV.

Thus, the limiting reaction in the CNO cycle, proton capture by 14
7N
, has S(E0) ~ S(0) = 3.5 keV b, while the limiting reaction in the proton-proton chain reaction, the creation of deuterium from two protons, has a much lower S(E0) ~ S(0) = 4*10−22 keV b.[35][36] Incidentally, since the former reaction has a much higher Gamow factor, and due to the relative abundance of elements in typical stars, the two reaction rates are equal at a temperature value that is within the core temperature ranges of main-sequence stars.
References

Hoyle, F. (1946). "The synthesis of the elements from hydrogen". Monthly Notices of the Royal Astronomical Society. 106 (5): 343–383. Bibcode:1946MNRAS.106..343H. doi:10.1093/mnras/106.5.343.
Hoyle, F. (1954). "On Nuclear Reactions Occurring in Very Hot STARS. I. The Synthesis of Elements from Carbon to Nickel". The Astrophysical Journal Supplement Series. 1: 121. Bibcode:1954ApJS....1..121H. doi:10.1086/190005.
Burbidge, E. M.; Burbidge, G. R.; Fowler, W.A.; Hoyle, F. (1957). "Synthesis of the Elements in Stars" (PDF). Reviews of Modern Physics. 29 (4): 547–650. Bibcode:1957RvMP...29..547B. doi:10.1103/RevModPhys.29.547.
Suess, H. E.; Urey, H. C. (1956). "Abundances of the Elements". Reviews of Modern Physics. 28 (1): 53–74. Bibcode:1956RvMP...28...53S. doi:10.1103/RevModPhys.28.53.
Clayton, D. D. (1968). Principles of Stellar Evolution and Nucleosynthesis. University of Chicago Press.
Eddington, A. S. (1920). "The internal constitution of the stars". The Observatory. 43 (1341): 341–358. Bibcode:1920Obs....43..341E. doi:10.1126/science.52.1341.233. PMID 17747682.
Eddington, A. S (1920). "The Internal Constitution of the Stars". Nature. 106 (2653): 14. Bibcode:1920Natur.106...14E. doi:10.1038/106014a0. PMID 17747682.
Selle, D. (October 2012). "Why the Stars Shine" (PDF). Guidestar. Houston Astronomical Society. pp. 6–8. Archived (PDF) from the original on 2013-12-03.
Krane, K. S., Modern Physics (Hoboken, NJ: Wiley, 1983), p. 410.
Bethe, H. A. (1939). "Energy Production in Stars". Physical Review. 55 (5): 434–456. Bibcode:1939PhRv...55..434B. doi:10.1103/PhysRev.55.434. PMID 17835673.
Lang, K. R. (2013). The Life and Death of Stars. Cambridge University Press. p. 167. ISBN 978-1-107-01638-5..
Clayton, D. D. (2007). "History of Science: Hoyle's Equation". Science. 318 (5858): 1876–1877. doi:10.1126/science.1151167. PMID 18096793. S2CID 118423007.
Cameron, A. G. W. (1957). Stellar Evolution, Nuclear Astrophysics, and Nucleogenesis (PDF) (Report). Atomic Energy of Canada Limited. Report CRL-41.
Clayton, D. D.; Fowler, W. A.; Hull, T. E.; Zimmerman, B. A. (1961). "Neutron capture chains in heavy element synthesis". Annals of Physics. 12 (3): 331–408. Bibcode:1961AnPhy..12..331C. doi:10.1016/0003-4916(61)90067-7.
Seeger, P. A.; Fowler, W. A.; Clayton, D. D. (1965). "Nucleosynthesis of Heavy Elements by Neutron Capture". The Astrophysical Journal Supplement Series. 11: 121–126. Bibcode:1965ApJS...11..121S. doi:10.1086/190111.
Bodansky, D.; Clayton, D. D.; Fowler, W. A. (1968). "Nucleosynthesis During Silicon Burning". Physical Review Letters. 20 (4): 161–164. Bibcode:1968PhRvL..20..161B. doi:10.1103/PhysRevLett.20.161.
Bodansky, D.; Clayton, D. D.; Fowler, W. A. (1968). "Nuclear Quasi-Equilibrium during Silicon Burning". The Astrophysical Journal Supplement Series. 16: 299. Bibcode:1968ApJS...16..299B. doi:10.1086/190176.
Clayton, D. D. (1964). "Cosmoradiogenic Chronologies of Nucleosynthesis". The Astrophysical Journal. 139: 637. Bibcode:1964ApJ...139..637C. doi:10.1086/147791.
Jones, Lauren V. (2009), Stars and galaxies, Greenwood guides to the universe, ABC-CLIO, pp. 65–67, ISBN 978-0-313-34075-8
Böhm-Vitense, Erika (1992), Introduction to Stellar Astrophysics, 3, Cambridge University Press, pp. 93–100, ISBN 978-0-521-34871-3
Reiners, A.; Basri, G. (March 2009). "On the magnetic topology of partially and fully convective stars". Astronomy and Astrophysics. 496 (3): 787–790.arXiv:0901.1659. Bibcode:2009A&A...496..787R. doi:10.1051/0004-6361:200811450. S2CID 15159121.
de Loore, Camiel W. H.; Doom, C. (1992), Structure and evolution of single and binary stars, Astrophysics and space science library, 179, Springer, pp. 200–214, ISBN 978-0-7923-1768-5
Jeffrey, C. Simon (2010), Goswami, A.; Reddy, B. E. (eds.), "Principles and Perspectives in Cosmochemistry", Astrophysics and Space Science Proceedings, Springer, 16: 64–66, Bibcode:2010ASSP...16.....G, doi:10.1007/978-3-642-10352-0, ISBN 978-3-642-10368-1
Karttunen, Hannu; Oja, Heikki (2007), Fundamental astronomy (5th ed.), Springer, p. 247, ISBN 978-3-540-34143-7.
Choppin, G. R., Liljenzin, J.-O., Rydberg, J., & Ekberg, C., Radiochemistry and Nuclear Chemistry (Cambridge, MA: Academic Press, 2013), p. 357.
Agostini, M.; Altenmüller, K.; Appel, S.; Atroshchenko, V.; Bagdasarian, Z.; Basilico, D.; Bellini, G.; Benziger, J.; Biondi, R.; Bravo, D.; Caccianiga, B. (25 November 2020). "Experimental evidence of neutrinos produced in the CNO fusion cycle in the Sun". Nature. 587 (7835): 577–582. doi:10.1038/s41586-020-2934-0. ISSN 1476-4687. PMID 33239797. "This result therefore paves the way towards a direct measurement of the solar metallicity using CNO neutrinos. Our findings quantify the relative contribution of CNO fusion in the Sun to be of the order of 1 per cent."
"Neutrinos yield first experimental evidence of catalyzed fusion dominant in many stars". phys.org. Retrieved 2020-11-26. "Pocar points out, ‘Confirmation of CNO burning in our sun, where it operates at only one percent, reinforces our confidence that we understand how stars work.’"
Reid, I. Neill; Hawley, Suzanne L. (2005), New light on dark stars: red dwarfs, low-mass stars, brown dwarfs, Springer-Praxis books in astrophysics and astronomy (2nd ed.), Springer, p. 108, ISBN 978-3-540-25124-8.
Salaris, Maurizio; Cassisi, Santi (2005), Evolution of stars and stellar populations, John Wiley and Sons, pp. 119–123, ISBN 978-0-470-09220-0
Schuler, S. C.; King, J. R.; The, L.-S. (2009), "Stellar Nucleosynthesis in the Hyades Open Cluster", The Astrophysical Journal, 701 (1): 837–849,arXiv:0906.4812, Bibcode:2009ApJ...701..837S, doi:10.1088/0004-637X/701/1/837, S2CID 10626836
Karttunen, H., Kröger, P., Oja, H., Poutanen, M., & Donner, K. J., eds., Fundamental Astronomy (Berlin/Heidelberg: Springer, 1987), p. 250.
Rehder, D., Chemistry in Space: From Interstellar Matter to the Origin of Life (Weinheim: Wiley-VCH, 2010), p. 30.
Iliadis, C., Nuclear Physics of Stars (Weinheim: Wiley-VCH, 2015), p. 185.
"University College London astrophysics course: lecture 7 – Stars" (PDF). Archived from the original (PDF) on January 15, 2017. Retrieved May 8, 2020.
Adelberger, Eric G.; Austin, Sam M.; Bahcall, John N.; Balantekin, A. B.; Bogaert, Gilles; Brown, Lowell S.; Buchmann, Lothar; Cecil, F. Edward; Champagne, Arthur E.; de Braeckeleer, Ludwig; Duba, Charles A. (1998-10-01). "Solar fusion cross sections". Reviews of Modern Physics. 70 (4): 1265–1291. arXiv:astro-ph/9805121. Bibcode:1998RvMP...70.1265A. doi:10.1103/RevModPhys.70.1265. ISSN 0034-6861. S2CID 16061677.

Adelberger, E. G. (2011). "Solar fusion cross sections. II. Theppchain and CNO cycles". Reviews of Modern Physics. 83 (1): 195–245.arXiv:1004.2318. Bibcode:2011RvMP...83..195A. doi:10.1103/RevModPhys.83.195. S2CID 119117147.

Further reading

Bethe, H. A. (1939). "Energy Production in Stars". Physical Review. 55 (1): 541–7. Bibcode:1939PhRv...55..103B. doi:10.1103/PhysRev.55.103. PMID 17835673.
Bethe, H. A. (1939). "Energy Production in Stars". Physical Review. 55 (5): 434–456. Bibcode:1939PhRv...55..434B. doi:10.1103/PhysRev.55.434. PMID 17835673.
Hoyle, F. (1954). "On Nuclear Reactions occurring in very hot stars: Synthesis of elements from carbon to nickel". Astrophysical Journal Supplement. 1: 121–146. Bibcode:1954ApJS....1..121H. doi:10.1086/190005.
Clayton, Donald D. (1968). Principles of Stellar Evolution and Nucleosynthesis. New York: McGraw-Hill.
Ray, A. (2004). "Stars as thermonuclear reactors: Their fuels and ashes". arXiv:astro-ph/0405568.
G. Wallerstein; I. Iben, Jr.; P. Parker; A. M. Boesgaard; G. M. Hale; A. E. Champagne; et al. (1997). "Synthesis of the elements in stars: forty years of progress" (PDF). Reviews of Modern Physics. 69 (4): 995–1084. Bibcode:1997RvMP...69..995W. doi:10.1103/RevModPhys.69.995. hdl:2152/61093. Archived from the original (PDF) on 2009-03-26. Retrieved 2006-08-04.
Woosley, S. E.; A. Heger; T. A. Weaver (2002). "The evolution and explosion of massive stars". Reviews of Modern Physics. 74 (4): 1015–1071. Bibcode:2002RvMP...74.1015W. doi:10.1103/RevModPhys.74.1015. S2CID 55932331.
Clayton, Donald D. (2003). Handbook of Isotopes in the Cosmos. Cambridge: Cambridge University Press. ISBN 978-0-521-82381-4.

External links

How the Sun Shines by John N. Bahcall (Nobel prize site, accessed 6 January 2020)
Nucleosynthesis in NASA's Cosmicopia

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Stars
Formation

Accretion Molecular cloud Bok globule Young stellar object
Protostar Pre-main-sequence Herbig Ae/Be T Tauri FU Orionis Herbig–Haro object Hayashi track Henyey track

Evolution

Main sequence Red-giant branch Horizontal branch
Red clump Asymptotic giant branch
super-AGB Blue loop Protoplanetary nebula Planetary nebula PG1159 Dredge-up OH/IR Instability strip Luminous blue variable Blue straggler Stellar population Supernova Superluminous supernova / Hypernova

Spectral classification

Early Late Main sequence
O B A F G K M Brown dwarf WR OB Subdwarf
O B Subgiant Giant
Blue Red Yellow Bright giant Supergiant
Blue Red Yellow Hypergiant
Yellow Carbon
S CN CH White dwarf Chemically peculiar
Am Ap/Bp HgMn Helium-weak Barium Extreme helium Lambda Boötis Lead Technetium Be
Shell B[e]

Remnants

White dwarf
Helium planet Black dwarf Neutron
Radio-quiet Pulsar
Binary X-ray Magnetar Stellar black hole X-ray binary
Burster

Hypothetical

Blue dwarf Green Black dwarf Exotic
Boson Electroweak Strange Preon Planck Dark Dark-energy Quark Q Black Gravastar Frozen Quasi-star Thorne–Żytkow object Iron Blitzar

Stellar nucleosynthesis

Deuterium burning Lithium burning Proton–proton chain CNO cycle Helium flash Triple-alpha process Alpha process Carbon burning Neon burning Oxygen burning Silicon burning S-process R-process Fusor Nova
Symbiotic Remnant Luminous red nova

Structure

Core Convection zone
Microturbulence Oscillations Radiation zone Atmosphere
Photosphere Starspot Chromosphere Stellar corona Stellar wind
Bubble Bipolar outflow Accretion disk Asteroseismology
Helioseismology Eddington luminosity Kelvin–Helmholtz mechanism

Properties

Designation Dynamics Effective temperature Luminosity Kinematics Magnetic field Absolute magnitude Mass Metallicity Rotation Starlight Variable Photometric system Color index Hertzsprung–Russell diagram Color–color diagram

Star systems

Binary
Contact Common envelope Eclipsing Symbiotic Multiple Cluster
Open Globular Super Planetary system

Earth-centric
observations

Sun
Solar System Sunlight Pole star Circumpolar Constellation Asterism Magnitude
Apparent Extinction Photographic Radial velocity Proper motion Parallax Photometric-standard

Lists

Proper names
Arabic Chinese Extremes Most massive Highest temperature Lowest temperature Largest volume Smallest volume Brightest
Historical Most luminous Nearest
Nearest bright With exoplanets Brown dwarfs White dwarfs Milky Way novae Supernovae
Candidates Remnants Planetary nebulae Timeline of stellar astronomy

Related articles

Substellar object
Brown dwarf Sub-brown dwarf Planet Galactic year Galaxy Guest Gravity Intergalactic Planet-hosting stars Tidal disruption event

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Nuclear processes
Radioactive decay

Alpha decay Beta decay Gamma radiation Cluster decay Double beta decay Double electron capture Internal conversion Isomeric transition Neutron emission Positron emission Proton emission Spontaneous fission

Stellar nucleosynthesis

Deuterium fusion Lithium burning pp-chain CNO cycle α process Triple-α C burning Ne burning O burning Si burning r-process s-process p-process rp-process

Other
processes

Photodisintegration Photofission

Capture

Electron capture Neutron capture Proton capture

Exchange

(n-p) reaction

Physics Encyclopedia

World

Index

Hellenica World - Scientific Library

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