568:, carbon and oxygen accumulate in the core as helium is burned, while hydrogen burning shifts to further-out layers, resulting in an intermediate helium shell. However, the boundaries of these shells do not shift outward at the same rate due to differing critical temperatures and temperature sensitivities for hydrogen and helium burning. When the temperature at the inner boundary of the helium shell is no longer high enough to sustain helium burning, the core contracts and heats up, while the hydrogen shell (and thus the star's radius) expand outward. Core contraction and shell expansion continue until the core becomes hot enough to reignite the surrounding helium. This process continues cyclically – with a period on the order of 1000 years – and stars undergoing this process have periodically variable luminosity. These stars also lose material from their outer layers in a
1828:
63:
1900:
27:
1864:
1888:
1840:
1876:
1852:
560:
is once more established and the star begins to "burn" helium at its core and hydrogen in a spherical layer above the core. The star enters a steady helium-burning phase which lasts about 10% of the time it spent on the main sequence (the Sun is expected to burn helium at its core for about a billion
690:
An excited state of the C nucleus exists a little (0.3193 MeV) above the energy level of Be + He. This is necessary because the ground state of C is 7.3367 MeV below the energy of Be + He; a Be nucleus and a He nucleus cannot reasonably fuse directly into a ground-state C nucleus. However,
620:
who, in 1953, used the abundance of carbon-12 in the universe as evidence for the existence of a carbon-12 resonance. The only way Hoyle could find that would produce an abundance of both carbon and oxygen was through a triple-alpha process with a carbon-12 resonance near 7.68 MeV, which would
531:
pressure. The entire degenerate core is at the same temperature and pressure, so when its density becomes high enough, fusion via the triple-alpha process rate starts throughout the core. The core is unable to expand in response to the increased energy production until the pressure is high enough
695:
of their collision to fuse into the excited C (kinetic energy supplies the additional 0.3193 MeV necessary to reach the excited state), which can then transition to its stable ground state. According to one calculation, the energy level of this excited state must be between about 7.3 MeV
976:
Pian, E.; d'Avanzo, P.; Benetti, S.; Branchesi, M.; Brocato, E.; Campana, S.; Cappellaro, E.; Covino, S.; d'Elia, V.; Fynbo, J. P. U.; Getman, F.; Ghirlanda, G.; Ghisellini, G.; Grado, A.; Greco, G.; Hjorth, J.; Kouveliotou, C.; Levan, A.; Limatola, L.; Malesani, D.; Mazzali, P. A.; Melandri, A.;
628:
and said that there had to be a resonance of 7.68 MeV in the carbon-12 nucleus. (There had been reports of an excited state at about 7.5 MeV.) Fred Hoyle's audacity in doing this is remarkable, and initially, the nuclear physicists in the lab were skeptical. Finally, a junior physicist,
408:, but these reactions are only significant at higher temperatures and pressures than in cores undergoing the triple-alpha process. This creates a situation in which stellar nucleosynthesis produces large amounts of carbon and oxygen, but only a small fraction of those elements are converted into
612:
had calculated the reaction rate for Be, C, and O nucleosynthesis taking this resonance into account. However, Salpeter calculated that red giants burned helium at temperatures of 2·10 K or higher, whereas other recent work hypothesized temperatures as low as 1.1·10 K for the core of a red
696:
and 7.9 MeV to produce sufficient carbon for life to exist, and must be further "fine-tuned" to between 7.596 MeV and 7.716 MeV in order to produce the abundant level of C observed in nature. The Hoyle state has been measured to be about 7.65 MeV above the ground state of C.
637:
that was not being used. Hoyle was back in
Cambridge when Fowler's lab discovered a carbon-12 resonance near 7.65 MeV a few months later, validating his prediction. The nuclear physicists put Hoyle as first author on a paper delivered by Whaling at the summer meeting of the
128:
to fuse in its core, it begins to contract and heat up. If the central temperature rises to 10 K, six times hotter than the Sun's core, alpha particles can fuse fast enough to get past the beryllium-8 barrier and produce significant amounts of stable carbon-12.
730:
hypothesis, life can only evolve in the minority of universes where the fundamental constants happen to be fine-tuned to support the existence of life. Other scientists reject the hypothesis of the multiverse on account of the lack of independent evidence.
699:
In the reaction C + He → O, there is an excited state of oxygen which, if it were slightly higher, would provide a resonance and speed up the reaction. In that case, insufficient carbon would exist in nature; almost all of it would have converted to
454:
before its actual observation, based on the physical necessity for it to exist, in order for carbon to be formed in stars. The prediction and then discovery of this energy resonance and process gave very significant support to Hoyle's hypothesis of
507:
The triple-alpha steps are strongly dependent on the temperature and density of the stellar material. The power released by the reaction is approximately proportional to the temperature to the 40th power, and the density squared. In contrast, the
438:
Ordinarily, the probability of the triple-alpha process is extremely small. However, the beryllium-8 ground state has almost exactly the energy of two alpha particles. In the second step, Be + He has almost exactly the energy of an
977:
Møller, P.; Nicastro, L.; Palazzi, E.; Piranomonte, S.; Rossi, A.; Salafia, O. S.; Selsing, J.; et al. (2017). "Spectroscopic identification of r-process nucleosynthesis in a double neutron-star merger".
556:, although no effects will be immediately observed at the surface, as the whole energy is used up to lift the core from the degenerate to normal, gaseous state. Since the core is no longer degenerate,
516:
at about the 17th power of the temperature, and both are linearly proportional to the density. This strong temperature dependence has consequences for the late stage of stellar evolution, the
657:
reaction channel was not observed, and this meant the state must be a 0+ state. This state completely suppresses single gamma emission, since single gamma emission must carry away at least 1
616:
Salpeter's paper mentioned in passing the effects that unknown resonances in carbon-12 would have on his calculations, but the author never followed up on them. It was instead astrophysicist
124:, which nearly always decays back into three alpha particles, but once in about 2421.3 times releases energy and changes into the stable base form of carbon-12. When a star runs out of
450:
greatly increases the probability that an incoming alpha particle will combine with beryllium-8 to form carbon. The existence of this resonance was predicted by
532:
to lift the degeneracy. As a consequence, the temperature increases, causing an increased reaction rate in a positive feedback cycle that becomes a
463:
has been cited to explain the fact that nuclear resonances are sensitively arranged to create large amounts of carbon and oxygen in the universe.
604:. Based on known resonances, by 1952 it seemed impossible for ordinary stars to produce carbon as well as any heavier element. Nuclear physicist
1466:
78:
fusion processes at different temperatures (T). The dashed line shows the combined energy generation of the PP and CNO processes within a star.
1331:
Livio, M.; Hollowell, D.; Weiss, A.; Truran, J. W. (27 July 1989). "The anthropic significance of the existence of an excited state of C".
665:
from an excited 0+ state is possible because their combined spins (0) can couple to a reaction that has a change in angular momentum of 0.
1563:
679:
Carbon is a necessary component of all known life. C, a stable isotope of carbon, is abundantly produced in stars due to three factors:
295:
As a side effect of the process, some carbon nuclei fuse with additional helium to produce a stable isotope of oxygen and energy:
1945:
1072:
1047:
819:
772:
1414:
947:
1278:
Uzan, Jean-Philippe (April 2003). "The fundamental constants and their variation: observational and theoretical status".
459:, which posited that all chemical elements had originally been formed from hydrogen, the true primordial substance. The
1121:
922:
509:
90:
67:
1827:
642:. A long and fruitful collaboration between Hoyle and Fowler soon followed, with Fowler even coming to Cambridge.
1556:
704:
Some scholars argue the 7.656 MeV Hoyle resonance, in particular, is unlikely to be the product of mere chance.
483:); heavier elements (those beyond Ni) are created mainly by neutron capture. The slow capture of neutrons, the
658:
540:, lasts a matter of seconds but burns 60–80% of the helium in the core. During the core flash, the star's
447:
113:
633:, who was looking for a project decided to look for the resonance. Fowler permitted Whaling to use an old
487:, produces about half of elements beyond iron. The other half are produced by rapid neutron capture, the
112:, unless within that time a third alpha particle fuses with the beryllium-8 nucleus to produce an excited
803:
1088:
687:
nucleus is four orders of magnitude larger than the time for two He nuclei (alpha particles) to scatter.
1818:
1549:
639:
1925:
421:
1143:
Kragh, Helge (2010) When is a prediction anthropic? Fred Hoyle and the 7.65 MeV carbon resonance.
1920:
1715:
1680:
1660:
1615:
634:
565:
557:
492:
456:
401:
430:. One consequence of this is that no significant amount of carbon was produced in the Big Bang.
1710:
1700:
1112:
Carroll, Bradley W.; Ostlie, Dale A. (2010). "Thermal pulses and the asymptotic giant branch".
605:
1204:
1705:
1517:
1390:
1340:
1297:
1249:
1238:
Cook, CW; Fowler, W.; Lauritsen, C.; Lauritsen, T. (1957). "12B, 12C, and the Red Giants".
1212:
1200:
1165:
996:
859:
714:
889:, Morten Hjorth-Jensen, Department of Physics and Center of Mathematics for Applications,
8:
1892:
1759:
1650:
1630:
1625:
914:
789:
727:
722:
argument. Instead, some scientists believe that different universes, portions of a vast "
674:
496:
460:
389:, which also is highly unstable, and decays back into smaller nuclei with a half-life of
1521:
1394:
1344:
1301:
1253:
1169:
1000:
871:
863:
1935:
1880:
1868:
1507:
1448:
1406:
1356:
1313:
1287:
1020:
986:
894:
890:
844:
719:
573:
426:
The triple-alpha process is ineffective at the pressures and temperatures early in the
645:
The final reaction product lies in a 0+ state (spin 0 and positive parity). Since the
1640:
1610:
1580:
1317:
1117:
1068:
1043:
1012:
918:
825:
815:
768:
528:
1410:
911:
Astronomy through the ages the story of the human attempt to understand the universe
104:, which is highly unstable, and decays back into smaller nuclei with a half-life of
1844:
1670:
1635:
1620:
1572:
1525:
1440:
1398:
1360:
1348:
1305:
1257:
1208:
1173:
1024:
1004:
867:
709:
581:
545:
524:
1940:
1930:
1780:
1675:
1645:
1240:
662:
630:
541:
533:
527:, the helium accumulating in the core is prevented from further collapse only by
121:
1375:
788:
Bohan, Elise; Dinwiddie, Robert; Challoner, Jack; Stuart, Colin; Harvey, Derek;
412:
and heavier elements. Oxygen and carbon are the main "ash" of helium-4 burning.
1904:
1832:
1801:
1785:
1402:
939:
909:
Wilson, Robert (1997). "Chapter 11: The Stars – their Birth, Life, and Death".
811:
692:
654:
609:
512:
produces energy at a rate proportional to the fourth power of temperature, the
400:
Fusing with additional helium nuclei can create heavier elements in a chain of
47:
39:
1309:
1914:
1690:
1605:
1471:
829:
807:
440:
405:
20:
1261:
708:
argued in 1982 that the Hoyle resonance was evidence of a "superintellect";
471:
With further increases of temperature and density, fusion processes produce
62:
1856:
1764:
1016:
943:
793:
569:
537:
86:
797:
653:
were expected to be seen. However, when experiments were carried out, the
649:
was predicted to be either a 0+ or a 2+ state, electron–positron pairs or
1590:
884:
726:", have different fundamental constants: according to this controversial
684:
646:
597:
443:
178:
101:
1452:
1444:
1144:
1008:
796:; Hubbard, Ben; Parker, Phillip; et al. (Writers) (February 2016).
1741:
1595:
1292:
1156:
Salpeter, E. E. (1952). "Nuclear
Reactions in Stars Without Hydrogen".
747:
723:
705:
617:
549:
451:
26:
1899:
1736:
1728:
1720:
1685:
1600:
1352:
748:
Appenzeller; Harwit; Kippenhahn; Strittmatter; Trimble, eds. (1998).
650:
593:
577:
517:
513:
488:
484:
476:
386:
342:
300:
243:
117:
94:
71:
1541:
1530:
1495:
1177:
991:
843:
Audi, G.; Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S. (2017).
601:
427:
321:
138:
125:
43:
1512:
1467:"Stars burning strangely make life in the multiverse more likely"
1067:(2nd ed.). Addison-Wesley, San Francisco. pp. 461–462.
1042:(2nd ed.). Addison-Wesley, San Francisco. pp. 312–313.
625:
472:
1228:, Simon Mitton, Cambridge University Press, 2011, pages 205–209.
1065:
An
Introduction to the Theory of Stellar Structure and Evolution
975:
553:
363:
264:
82:
51:
1116:(2nd ed.). Cambridge University Press. pp. 168–173.
787:
1237:
621:
also eliminate the discrepancy in
Salpeter's calculations.
480:
409:
1851:
1056:
962:
Fred Hoyle, "The
Universe: Past and Present Reflections."
385:
Nuclear fusion reactions of helium with hydrogen produces
1330:
19:"Helium burning" redirects here. Not to be confused with
16:
Nuclear fusion reaction chain converting helium to carbon
756:
100:
Nuclear fusion reaction of two helium-4 nuclei produces
1031:
938:
1496:"The fine-tuning of the universe for intelligent life"
502:
1816:
1500:
466:
292:
The net energy release of the process is 7.275 MeV.
1431:Peacock, John (2006). "A Universe Tuned for Life".
1191:Salpeter, E. E. (2002). "A Generalist Looks Back".
842:
763:Carroll, Bradley W. & Ostlie, Dale A. (2007).
845:"The NUBASE2016 evaluation of nuclear properties"
600:having resonances with slightly more energy than
1912:
668:
592:The triple-alpha process is highly dependent on
57:
765:An Introduction to Modern Stellar Astrophysics
1557:
1111:
1038:Carroll, Bradley W.; Ostlie, Dale A. (2006).
1037:
762:
564:In higher mass stars, which evolve along the
1273:
1271:
1105:
1564:
1550:
1373:
741:
1529:
1511:
1291:
1268:
990:
836:
608:had noted the beryllium-8 resonance, and
1383:Progress in Particle and Nuclear Physics
1190:
1155:
1149:
1139:
1137:
1135:
1133:
1062:
61:
25:
1430:
66:Comparison of the energy output (ε) of
1913:
1493:
1213:10.1146/annurev.astro.40.060401.093901
1114:An Introduction to Modern Astrophysics
1040:An Introduction to Modern Astrophysics
908:
1571:
1545:
1145:http://philsci-archive.pitt.edu/5332/
1130:
966:, November, 1981. pp. 8–12
536:reaction. This process, known as the
1277:
949:The Anthropic Cosmological Principle
415:
30:Overview of the triple-alpha process
1374:Freer, M.; Fynbo, H. O. U. (2014).
969:
893:, N-0316 Oslo, Norway: 9 May 2011,
752:(3rd ed.). New York: Springer.
503:Reaction rate and stellar evolution
13:
781:
14:
1957:
767:. Addison Wesley, San Francisco.
467:Nucleosynthesis of heavy elements
1898:
1886:
1874:
1862:
1850:
1838:
1826:
1420:from the original on 2022-07-18.
1487:
1459:
1424:
1367:
1324:
1231:
1219:
1184:
1081:
561:years after the helium flash).
956:
931:
902:
878:
624:Hoyle went to Fowler's lab at
1:
1946:Stellar astrophysics concepts
1226:Fred Hoyle, A Life in Science
1093:faculty.wcas.northwestern.edu
872:10.1088/1674-1137/41/3/030001
734:
669:Improbability and fine-tuning
576:, which ultimately becomes a
433:
58:Triple-alpha process in stars
1193:Annu. Rev. Astron. Astrophys
587:
523:For lower mass stars on the
510:proton–proton chain reaction
95:carbon–nitrogen–oxygen cycle
91:proton–proton chain reaction
89:of stars as a result of the
7:
548:which is comparable to the
544:can reach approximately 10
491:, which probably occurs in
10:
1962:
1403:10.1016/j.ppnp.2014.06.001
672:
419:
18:
1794:
1773:
1750:
1659:
1579:
1310:10.1103/RevModPhys.75.403
1280:Reviews of Modern Physics
1158:The Astrophysical Journal
806:(1st American ed.).
640:American Physical Society
629:Ward Whaling, fresh from
42:reactions by which three
683:The decay lifetime of a
659:unit of angular momentum
493:core-collapse supernovae
422:Big Bang nucleosynthesis
1616:Double electron capture
1494:Barnes, Luke A (2012).
1262:10.1103/PhysRev.107.508
1205:2002ARA&A..40....1S
1063:Prialnik, Dina (2006).
964:Engineering and Science
635:Van de Graaff generator
580:as the star enters the
566:asymptotic giant branch
558:hydrostatic equilibrium
479:(which decays later to
457:stellar nucleosynthesis
402:stellar nucleosynthesis
50:) are transformed into
1376:"The Hoyle state in C"
79:
31:
606:William Alfred Fowler
65:
29:
1089:"The End Of The Sun"
915:Taylor & Francis
886:The carbon challenge
790:Wragg-Sykes, Rebecca
750:Astrophysics Library
715:The Cosmic Landscape
497:neutron star mergers
199: (−0.0918 MeV)
36:triple-alpha process
1760:Photodisintegration
1681:Proton–proton chain
1651:Spontaneous fission
1631:Isomeric transition
1626:Internal conversion
1522:2012PASA...29..529B
1445:10.1511/2006.58.168
1395:2014PrPNP..78....1F
1345:1989Natur.340..281L
1302:2003RvMP...75..403U
1254:1957PhRv..107..508C
1170:1952ApJ...115..326S
1009:10.1038/nature24298
1001:2017Natur.551...67P
864:2017ChPhC..41c0001A
675:Fine-tuned universe
529:electron degeneracy
461:anthropic principle
284: (+7.367 MeV)
85:accumulates in the
1475:. 1 September 2016
1433:American Scientist
891:University of Oslo
720:intelligent design
691:Be and He use the
574:radiation pressure
546:solar luminosities
80:
32:
1814:
1813:
1810:
1809:
1641:Positron emission
1611:Double beta decay
1573:Nuclear processes
1339:(6231): 281–284.
1074:978-0-8053-0402-2
1049:978-0-8053-0402-2
852:Chinese Physics C
821:978-1-4654-5443-0
774:978-0-8053-0348-3
542:energy production
416:Primordial carbon
288:
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1953:
1903:
1902:
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1877:
1867:
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1865:
1855:
1854:
1843:
1842:
1841:
1831:
1830:
1822:
1771:
1770:
1671:Deuterium fusion
1636:Neutron emission
1621:Electron capture
1566:
1559:
1552:
1543:
1542:
1536:
1535:
1533:
1515:
1491:
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1428:
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1419:
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1371:
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1353:10.1038/340281a0
1328:
1322:
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1235:
1229:
1223:
1217:
1216:
1188:
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1153:
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1141:
1128:
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1103:
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1099:
1085:
1079:
1078:
1060:
1054:
1053:
1035:
1029:
1028:
994:
973:
967:
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954:
953:
935:
929:
928:
906:
900:
882:
876:
875:
849:
840:
834:
833:
785:
779:
778:
760:
754:
753:
745:
718:rejects Hoyle's
710:Leonard Susskind
582:planetary nebula
525:red-giant branch
396:
394:
380:
378:
377:
370:
369:
360:
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111:
109:
1961:
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1951:
1950:
1926:Nucleosynthesis
1911:
1910:
1909:
1897:
1887:
1885:
1875:
1873:
1863:
1861:
1849:
1839:
1837:
1825:
1817:
1815:
1806:
1790:
1781:Neutron capture
1769:
1752:
1746:
1663:nucleosynthesis
1662:
1655:
1646:Proton emission
1601:Gamma radiation
1582:
1575:
1570:
1540:
1539:
1531:10.1071/as12015
1492:
1488:
1478:
1476:
1465:
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1429:
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1417:
1378:
1372:
1368:
1329:
1325:
1276:
1269:
1241:Physical Review
1236:
1232:
1224:
1220:
1189:
1185:
1154:
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1142:
1131:
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1110:
1106:
1097:
1095:
1087:
1086:
1082:
1075:
1061:
1057:
1050:
1036:
1032:
985:(7678): 67–70.
974:
970:
961:
957:
936:
932:
925:
913:. Basingstoke:
907:
903:
883:
879:
847:
841:
837:
822:
804:David Christian
786:
782:
775:
761:
757:
746:
742:
737:
677:
671:
663:Pair production
631:Rice University
590:
505:
469:
436:
424:
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107:
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60:
48:alpha particles
24:
17:
12:
11:
5:
1959:
1949:
1948:
1943:
1938:
1933:
1928:
1923:
1921:Nuclear fusion
1908:
1907:
1895:
1883:
1871:
1859:
1847:
1835:
1812:
1811:
1808:
1807:
1805:
1804:
1802:(n-p) reaction
1798:
1796:
1792:
1791:
1789:
1788:
1786:Proton capture
1783:
1777:
1775:
1768:
1767:
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1506:(4): 529–564.
1486:
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1439:(2): 168–170.
1423:
1366:
1323:
1293:hep-ph/0205340
1286:(2): 403–455.
1267:
1248:(2): 508–515.
1230:
1218:
1183:
1178:10.1086/145546
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1129:
1122:
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1080:
1073:
1055:
1048:
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968:
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814:. p. 58.
802:. Foreword by
780:
773:
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739:
738:
736:
733:
702:
701:
697:
693:kinetic energy
688:
673:Main article:
670:
667:
655:gamma emission
610:Edwin Salpeter
589:
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504:
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468:
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420:Main article:
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40:nuclear fusion
15:
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1606:Cluster decay
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1472:New Scientist
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441:excited state
431:
429:
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411:
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406:alpha process
404:known as the
403:
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120:, called the
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92:
88:
84:
77:
73:
69:
68:proton–proton
64:
55:
53:
49:
45:
41:
37:
28:
22:
21:alpha process
1893:Solar System
1765:Photofission
1729:
1721:
1695:
1503:
1499:
1489:
1477:. Retrieved
1470:
1461:
1436:
1432:
1426:
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1113:
1107:
1096:. Retrieved
1092:
1083:
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1058:
1039:
1033:
982:
978:
971:
963:
958:
948:
944:Frank Tipler
933:
910:
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855:
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838:
798:
783:
764:
758:
749:
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623:
615:
591:
570:stellar wind
563:
538:helium flash
522:
506:
470:
437:
425:
399:
384:
381:(+7.162 MeV)
294:
291:
99:
81:
75:
38:is a set of
35:
33:
1881:Outer space
1869:Spaceflight
1591:Alpha decay
1581:Radioactive
1164:: 326–328.
940:John Barrow
799:Big History
728:fine-tuning
647:Hoyle state
598:beryllium-8
552:of a whole
475:only up to
122:Hoyle state
102:beryllium-8
1915:Categories
1742:rp-process
1716:Si burning
1706:Ne burning
1676:Li burning
1596:Beta decay
1479:15 January
1098:2020-07-29
992:1710.05858
735:References
724:multiverse
706:Fred Hoyle
651:gamma rays
618:Fred Hoyle
572:driven by
550:luminosity
452:Fred Hoyle
434:Resonances
1936:Beryllium
1845:Astronomy
1753:processes
1737:p-process
1711:O burning
1701:C burning
1691:α process
1686:CNO cycle
1513:1112.4647
1318:118684485
830:940282526
594:carbon-12
588:Discovery
578:superwind
518:red-giant
514:CNO cycle
489:r-process
485:s-process
477:nickel-56
448:resonance
395:10 s
387:lithium-5
118:carbon-12
116:state of
114:resonance
110:10 s
1795:Exchange
1732:-process
1724:-process
1696:Triple-α
1453:27858743
1415:Archived
1411:55187000
1389:: 1–23.
1199:: 1–25.
1017:29094694
946:(1986).
808:New York
602:helium-4
473:nuclides
428:Big Bang
126:hydrogen
93:and the
76:Triple-α
46:nuclei (
44:helium-4
1905:Science
1833:Physics
1819:Portals
1774:Capture
1661:Stellar
1518:Bibcode
1391:Bibcode
1361:4273737
1341:Bibcode
1298:Bibcode
1250:Bibcode
1201:Bibcode
1166:Bibcode
1025:3840214
997:Bibcode
896:Physics
860:Bibcode
700:oxygen.
626:Caltech
613:giant.
584:phase.
534:runaway
520:stage.
446:. This
1941:Carbon
1931:Helium
1451:
1409:
1359:
1333:Nature
1316:
1120:
1071:
1046:
1023:
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979:Nature
921:
828:
818:
771:
554:galaxy
371:γ
272:γ
83:Helium
70:(PP),
52:carbon
1857:Stars
1751:Other
1583:decay
1508:arXiv
1449:JSTOR
1418:(PDF)
1407:S2CID
1379:(PDF)
1357:S2CID
1314:S2CID
1288:arXiv
1021:S2CID
987:arXiv
899:4, 38
848:(PDF)
87:cores
1481:2017
1118:ISBN
1069:ISBN
1044:ISBN
1013:PMID
919:ISBN
826:OCLC
816:ISBN
769:ISBN
596:and
495:and
481:iron
444:of C
410:neon
106:8.19
74:and
34:The
1526:doi
1441:doi
1399:doi
1349:doi
1337:340
1306:doi
1258:doi
1246:107
1209:doi
1174:doi
1162:115
1005:doi
983:551
868:doi
712:in
391:3.7
262:+ 2
72:CNO
1917::
1524:.
1516:.
1504:29
1502:.
1498:.
1469:.
1447:.
1437:94
1435:.
1413:.
1405:.
1397:.
1387:78
1385:.
1381:.
1355:.
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1335:.
1312:.
1304:.
1296:.
1284:75
1282:.
1270:^
1256:.
1244:.
1207:.
1197:40
1195:.
1172:.
1160:.
1132:^
1091:.
1019:.
1011:.
1003:.
995:.
981:.
942:;
917:.
866:.
856:41
854:.
850:.
824:.
812:DK
810::
792:;
685:Be
661:.
499:.
397:.
361:+
340:→
330:He
319:+
241:→
232:He
222:+
213:Be
187:Be
176:→
167:He
157:+
147:He
97:.
54:.
1821::
1730:s
1722:r
1565:e
1558:t
1551:v
1534:.
1528::
1520::
1510::
1483:.
1455:.
1443::
1401::
1393::
1363:.
1351::
1343::
1320:.
1308::
1300::
1290::
1264:.
1260::
1252::
1215:.
1211::
1203::
1180:.
1176::
1168::
1126:.
1101:.
1077:.
1052:.
1027:.
1007::
999::
989::
952:.
927:.
874:.
870::
862::
832:.
777:.
393:×
351:O
347:8
326:2
309:C
305:6
252:C
248:6
228:2
209:4
183:4
163:2
143:2
108:×
23:.
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