Editing Supernova (section)

===Source of heavy elements===
{{Main|Stellar nucleosynthesis|Supernova nucleosynthesis}}
[[File:Nucleosynthesis periodic table.svg|thumb|upright=2|Periodic table showing the source of each element in the interstellar medium]]

Supernovae are a major source of elements in the interstellar medium from oxygen through to rubidium,<ref name=nucleosynthesis/><ref name="François">
{{Cite journal
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 |last4=Spite |first4=M.
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 |last6=Chiappini |first6=C.
 |date=2004
 |title=The evolution of the Milky Way from its earliest phases: Constraints on stellar nucleosynthesis
 |journal=[[Astronomy & Astrophysics]]
 |volume=421 |issue=2 |pages=613–621
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 }}</ref><ref name="Truran">
{{cite book
 |last=Truran |first=J. W.
 |year=1977
 |chapter=Supernova Nucleosynthesis
 |editor-last=Schramm |editor-first=D. N.
 |title=Supernovae
 |series=Astrophysics and Space Science Library
 |volume=66 |pages=145–158
 |publisher=[[Springer Science+Business Media|Springer]]
 |doi=10.1007/978-94-010-1229-4_14 |bibcode=1977ASSL...66..145T
 |isbn=978-94-010-1231-7
}}</ref> though the theoretical abundances of the elements produced or seen in the spectra varies significantly depending on the various supernova types.<ref name="Truran"/> Type Ia supernovae produce mainly silicon and iron-peak elements, metals such as nickel and iron.<ref name=nomoto2018>{{cite journal|doi=10.1007/s11214-018-0499-0|title=Single Degenerate Models for Type Ia Supernovae: Progenitor's Evolution and Nucleosynthesis Yields|journal=Space Science Reviews|volume=214|issue=4|year=2018|last1=Nomoto|first1=Ken'Ichi|last2=Leung|first2=Shing-Chi|pages=67|arxiv=1805.10811|bibcode=2018SSRv..214...67N|s2cid=118951927}}</ref><ref name=maeda>{{cite journal|doi=10.1088/0004-637X/712/1/624|title=Nucleosynthesis in Two-Dimensional Delayed Detonation Models of Type Ia Supernova Explosions|journal=The Astrophysical Journal|volume=712|pages=624–638|year=2010|last1=Maeda|first1=K.|last2=Röpke|first2=F.K.|last3=Fink|first3=M.|last4=Hillebrandt|first4=W.|last5=Travaglio|first5=C.|last6=Thielemann|first6=F.-K.|issue=1|arxiv=1002.2153|bibcode=2010ApJ...712..624M|s2cid=119290875}}</ref> Core collapse supernovae eject much smaller quantities of the iron-peak elements than type Ia supernovae, but larger masses of light [[alpha element]]s such as oxygen and neon, and elements heavier than zinc. The latter is especially true with electron capture supernovae.<ref>{{Cite journal|doi = 10.1088/2041-8205/726/2/L15|title = Electron-Capture Supernovae as the Origin of Elements Beyond Iron|year = 2011|last1 = Wanajo|first1 = Shinya|last2 = Janka|first2 = Hans-Thomas|last3 = Müller|first3 = Bernhard|journal = The Astrophysical Journal|volume = 726|issue = 2|pages = L15|arxiv = 1009.1000|bibcode = 2011ApJ...726L..15W|s2cid = 119221889}}</ref> The bulk of the material ejected by type II supernovae is hydrogen and helium.<ref name=eichler>{{cite journal|doi=10.1088/1361-6471/aa8891|title=Nucleosynthesis in 2D core-collapse supernovae of 11.2 and 17.0 M⊙ progenitors: Implications for Mo and Ru production|journal=Journal of Physics G: Nuclear and Particle Physics|volume=45|pages=014001|year=2018|last1=Eichler|first1=M.|last2=Nakamura|first2=K.|last3=Takiwaki|first3=T.|last4=Kuroda|first4=T.|last5=Kotake|first5=K.|last6=Hempel|first6=M.|last7=Cabezón|first7=R.|last8=Liebendörfer|first8=M.|last9=Thielemann|first9=F-K|issue=1|arxiv=1708.08393|bibcode=2018JPhG...45a4001E|s2cid=118936429}}</ref> The heavy elements are produced by: nuclear fusion for nuclei up to <sup>34</sup>S; silicon photodisintegration rearrangement and quasiequilibrium during silicon burning for nuclei between <sup>36</sup>Ar and <sup>56</sup>Ni; and rapid capture of neutrons ([[r-process]]) during the supernova's collapse for elements heavier than iron. <!--Nucleosynthesis during silicon burning yields nuclei roughly 1,000 to 100,000 times more abundant than the r-process isotopes heavier than iron.<ref>
{{Cite journal
 |last=Woosley |first=S. E.
 |last2=Arnett |first2=W. D.
 |last3=Clayton |first3=D. D.
 |date=1973
 |title=The Explosive Burning of Oxygen and Silicon
 |journal=[[Astrophysical Journal Supplement]]
 |volume=26 |pages=231–312
 |bibcode=1973ApJS...26..231W
 |doi=10.1086/190282
}}</ref>--> The r-process produces highly unstable nuclei that are rich in [[neutron]]s and that rapidly beta decay into more stable forms. In supernovae, r-process reactions are responsible for about half of all the isotopes of elements beyond iron,<ref>
{{Cite journal
 |last1=Qian |first1=Y.-Z.
 |last2=Vogel |first2=P.
 |last3=Wasserburg |first3=G. J.
 |date=1998
 |title=Diverse Supernova Sources for the r-Process
 |journal=[[Astrophysical Journal]]
 |volume=494 |issue=1 |pages=285–296
 |bibcode=1998ApJ...494..285Q
 |doi=10.1086/305198
|arxiv=astro-ph/9706120|s2cid=15967473
 }}</ref> although [[neutron star merger]]s may be the main astrophysical source for many of these elements.<ref name=nucleosynthesis>{{cite journal|doi=10.1126/science.aau9540|pmid=30705182|title=Populating the periodic table: Nucleosynthesis of the elements|journal=Science|volume=363|issue=6426|pages=474–478|year=2019|last1=Johnson|first1=Jennifer A.|bibcode=2019Sci...363..474J|s2cid=59565697|doi-access=free}}</ref><ref name=siegel>{{cite journal |doi=10.1038/s41586-019-1136-0 |pmid=31068724 |title=Collapsars as a major source of r-process elements |journal=Nature |volume=569 |issue=7755 |pages=241–244 |year=2019 |last1=Siegel |first1=Daniel M. |last2=Barnes |first2=Jennifer |last3=Metzger |first3=Brian D. |arxiv=1810.00098 |bibcode=2019Natur.569..241S |s2cid=73612090 }}</ref>

In the modern universe, old [[asymptotic giant branch]] (AGB) stars are the dominant source of dust from oxides, carbon and [[s-process]] elements.<ref name=nucleosynthesis/><ref>
{{cite journal
 |last1=Gonzalez |first1=G.
 |last2=Brownlee |first2=D.
 |last3=Ward |first3=P.
 |year=2001
 |title=The Galactic Habitable Zone: Galactic Chemical Evolution
 |journal=Icarus
 |volume=152 |issue=1 |pages=185
 |arxiv=astro-ph/0103165
 |bibcode=2001Icar..152..185G
 |doi=10.1006/icar.2001.6617
|s2cid=18179704
 }}</ref> However, in the early universe, before AGB stars formed, supernovae may have been the main source of dust.<ref name=dust>{{cite journal |bibcode=2019BAAS...51c.351R |arxiv=1904.08485 |last1=Rho |first1=Jeonghee |title=Astro2020 Science White Paper: Are Supernovae the Dust Producer in the Early Universe? |journal=Bulletin of the American Astronomical Society |volume=51 |issue=3 |pages=351 |last2=Milisavljevic |first2=Danny |last3=Sarangi |first3=Arkaprabha |last4=Margutti |first4=Raffaella |last5=Chornock |first5=Ryan |last6=Rest |first6=Armin |last7=Graham |first7=Melissa |last8=Craig Wheeler |first8=J. |last9=DePoy |first9=Darren |last10=Wang |first10=Lifan |last11=Marshall |first11=Jennifer |last12=Williams |first12=Grant |last13=Street |first13=Rachel |last14=Skidmore |first14=Warren |last15=Haojing |first15=Yan |last16=Bloom |first16=Joshua |last17=Starrfield|author17-link=Sumner Starrfield |first17=Sumner |last18=Lee |first18=Chien-Hsiu |last19=Cowperthwaite |first19=Philip S. |last20=Stringfellow |first20=Guy S. |last21=Coppejans |first21=Deanne |last22=Terreran |first22=Giacomo |last23=Sravan |first23=Niharika |last24=Geballe |first24=Thomas R. |last25=Evans |first25=Aneurin |last26=Marion |first26=Howie |year=2019 }}
</ref>