SherbyNet - /page/wikibook/entry.mu

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<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">Alpha process</span></span>

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<p>The <b>alpha process</b>, also known as <b>alpha capture</b> or the <b>alpha ladder</b>, is one of two classes of <a href="Nuclear_fusion" title="Nuclear fusion">nuclear fusion</a> reactions by which stars convert <a href="Helium" title="Helium">helium</a> into heavier <a href="Chemical_element" title="Chemical element">elements</a>. The other class is a cycle of reactions called the <a href="Triple-alpha_process" title="Triple-alpha process">triple-alpha process</a>, which consumes only helium, and produces <a href="Carbon" title="Carbon">carbon</a>.<sup id="cite_ref-narlikar_1-0" class="reference"><a href="#cite_note-narlikar-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> The alpha process most commonly occurs in massive stars and during <a href="Supernova" title="Supernova">supernovae</a>.

</p><p>Both processes are preceded by <a href="Hydrogen_fusion" class="mw-redirect" title="Hydrogen fusion">hydrogen fusion</a>, which produces the <a href="Helium" title="Helium">helium</a> that fuels both the triple-alpha process and the alpha ladder processes. After the <a href="Triple-alpha_process" title="Triple-alpha process">triple-alpha process</a> has produced enough carbon, the alpha-ladder begins and fusion reactions of increasingly heavy elements take place, in the order listed below. Each step only consumes the product of the previous reaction and helium. The later-stage reactions which are able to begin in any particular star, do so while the prior stage reactions are still under way in outer layers of the star.

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<dl><dd><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\begin{array}{ll}{\ce {~{}_{6}^{12}C\ ~~+{}_{2}^{4}He\ ->~{}_{8}^{16}O\ \ ~+\gamma ~,}}&E={\mathsf {7.16\ MeV}}\\{\ce {~{}_{8}^{16}O\ ~~+{}_{2}^{4}He\ ->{}_{10}^{20}Ne\ \ +\gamma ~,}}&E={\mathsf {4.73\ MeV}}\\{\ce {{}_{10}^{20}Ne\ ~+{}_{2}^{4}He\ ->{}_{12}^{24}Mg\ +\gamma ~,}}&E={\mathsf {9.32\ MeV}}\\{\ce {{}_{12}^{24}Mg\ +{}_{2}^{4}He\ ->{}_{14}^{28}Si\ ~~+\gamma ~,}}&E={\mathsf {9.98\ MeV}}\\{\ce {{}_{14}^{28}Si\ ~~+{}_{2}^{4}He\ ->{}_{16}^{32}S\ \ ~~~+\gamma ~,}}&E={\mathsf {6.95\ MeV}}\\{\ce {{}_{16}^{32}S\ ~~~+{}_{2}^{4}He\ ->{}_{18}^{36}Ar\ ~\ +\gamma ~,}}&E={\mathsf {6.64\ MeV}}\\{\ce {{}_{18}^{36}Ar\ ~+{}_{2}^{4}He\ ->{}_{20}^{40}Ca\ \ +\gamma ~,}}&E={\mathsf {7.04\ MeV}}\\{\ce {{}_{20}^{40}Ca\ +{}_{2}^{4}He\ ->{}_{22}^{44}Ti\ ~~+\gamma ~,}}&E={\mathsf {5.13\ MeV}}\\{\ce {{}_{22}^{44}Ti\ ~+{}_{2}^{4}He\ ->{}_{24}^{48}Cr\ ~+\gamma ~,}}&E={\mathsf {7.70\ MeV}}\\{\ce {{}_{24}^{48}Cr\ +{}_{2}^{4}He\ ->{}_{26}^{52}Fe\ ~\ +\gamma ~,}}&E={\mathsf {7.94\ MeV}}\\{\ce {{}_{26}^{52}Fe\ +{}_{2}^{4}He\ ->{}_{28}^{56}Ni\ ~\ +\gamma ~,}}&E={\mathsf {8.00\ MeV}}\end{array}}}">

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<annotation encoding="application/x-tex">{\displaystyle {\begin{array}{ll}{\ce {~{}_{6}^{12}C\ ~~+{}_{2}^{4}He\ ->~{}_{8}^{16}O\ \ ~+\gamma ~,}}&E={\mathsf {7.16\ MeV}}\\{\ce {~{}_{8}^{16}O\ ~~+{}_{2}^{4}He\ ->{}_{10}^{20}Ne\ \ +\gamma ~,}}&E={\mathsf {4.73\ MeV}}\\{\ce {{}_{10}^{20}Ne\ ~+{}_{2}^{4}He\ ->{}_{12}^{24}Mg\ +\gamma ~,}}&E={\mathsf {9.32\ MeV}}\\{\ce {{}_{12}^{24}Mg\ +{}_{2}^{4}He\ ->{}_{14}^{28}Si\ ~~+\gamma ~,}}&E={\mathsf {9.98\ MeV}}\\{\ce {{}_{14}^{28}Si\ ~~+{}_{2}^{4}He\ ->{}_{16}^{32}S\ \ ~~~+\gamma ~,}}&E={\mathsf {6.95\ MeV}}\\{\ce {{}_{16}^{32}S\ ~~~+{}_{2}^{4}He\ ->{}_{18}^{36}Ar\ ~\ +\gamma ~,}}&E={\mathsf {6.64\ MeV}}\\{\ce {{}_{18}^{36}Ar\ ~+{}_{2}^{4}He\ ->{}_{20}^{40}Ca\ \ +\gamma ~,}}&E={\mathsf {7.04\ MeV}}\\{\ce {{}_{20}^{40}Ca\ +{}_{2}^{4}He\ ->{}_{22}^{44}Ti\ ~~+\gamma ~,}}&E={\mathsf {5.13\ MeV}}\\{\ce {{}_{22}^{44}Ti\ ~+{}_{2}^{4}He\ ->{}_{24}^{48}Cr\ ~+\gamma ~,}}&E={\mathsf {7.70\ MeV}}\\{\ce {{}_{24}^{48}Cr\ +{}_{2}^{4}He\ ->{}_{26}^{52}Fe\ ~\ +\gamma ~,}}&E={\mathsf {7.94\ MeV}}\\{\ce {{}_{26}^{52}Fe\ +{}_{2}^{4}He\ ->{}_{28}^{56}Ni\ ~\ +\gamma ~,}}&E={\mathsf {8.00\ MeV}}\end{array}}}</annotation>

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</math></span><img src="./d026b97258ce4e64163c57e2879c73c259dc752a.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -19.022ex; margin-bottom: -0.316ex; width:46.666ex; height:39.843ex;" alt="{\displaystyle {\begin{array}{ll}{\ce {~{}_{6}^{12}C\ ~~+{}_{2}^{4}He\ ->~{}_{8}^{16}O\ \ ~+\gamma ~,}}&E={\mathsf {7.16\ MeV}}\\{\ce {~{}_{8}^{16}O\ ~~+{}_{2}^{4}He\ ->{}_{10}^{20}Ne\ \ +\gamma ~,}}&E={\mathsf {4.73\ MeV}}\\{\ce {{}_{10}^{20}Ne\ ~+{}_{2}^{4}He\ ->{}_{12}^{24}Mg\ +\gamma ~,}}&E={\mathsf {9.32\ MeV}}\\{\ce {{}_{12}^{24}Mg\ +{}_{2}^{4}He\ ->{}_{14}^{28}Si\ ~~+\gamma ~,}}&E={\mathsf {9.98\ MeV}}\\{\ce {{}_{14}^{28}Si\ ~~+{}_{2}^{4}He\ ->{}_{16}^{32}S\ \ ~~~+\gamma ~,}}&E={\mathsf {6.95\ MeV}}\\{\ce {{}_{16}^{32}S\ ~~~+{}_{2}^{4}He\ ->{}_{18}^{36}Ar\ ~\ +\gamma ~,}}&E={\mathsf {6.64\ MeV}}\\{\ce {{}_{18}^{36}Ar\ ~+{}_{2}^{4}He\ ->{}_{20}^{40}Ca\ \ +\gamma ~,}}&E={\mathsf {7.04\ MeV}}\\{\ce {{}_{20}^{40}Ca\ +{}_{2}^{4}He\ ->{}_{22}^{44}Ti\ ~~+\gamma ~,}}&E={\mathsf {5.13\ MeV}}\\{\ce {{}_{22}^{44}Ti\ ~+{}_{2}^{4}He\ ->{}_{24}^{48}Cr\ ~+\gamma ~,}}&E={\mathsf {7.70\ MeV}}\\{\ce {{}_{24}^{48}Cr\ +{}_{2}^{4}He\ ->{}_{26}^{52}Fe\ ~\ +\gamma ~,}}&E={\mathsf {7.94\ MeV}}\\{\ce {{}_{26}^{52}Fe\ +{}_{2}^{4}He\ ->{}_{28}^{56}Ni\ ~\ +\gamma ~,}}&E={\mathsf {8.00\ MeV}}\end{array}}}" loading="lazy"></span></dd></dl>

<p>The energy produced by each reaction, <span class="texhtml mvar" style="font-style:italic;">E</span>, is mainly in the form of <a href="Gamma_ray" title="Gamma ray">gamma rays</a> (<span class="texhtml mvar" style="font-style:italic;">γ</span>), with a small amount taken by the <a href="By-product" title="By-product">byproduct</a> element, as added <a href="Momentum" title="Momentum">momentum</a>.

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<p>It is a common misconception that the above sequence ends at <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \,{}_{28}^{56}\mathrm {Ni} \,}">

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<annotation encoding="application/x-tex">{\displaystyle \,{}_{28}^{56}\mathrm {Ni} \,}</annotation>

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</math></span><img src="./744eb653fc3d3be15ca2855fa63d04cb87497007.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:5.04ex; height:3.176ex;" alt="{\displaystyle \,{}_{28}^{56}\mathrm {Ni} \,}" loading="lazy"></span> (or <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \,{}_{26}^{56}\mathrm {Fe} \,}">

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<annotation encoding="application/x-tex">{\displaystyle \,{}_{26}^{56}\mathrm {Fe} \,}</annotation>

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</math></span><img src="./871fcc66489c06c7d8b0fc0b1c03c6a68f33debf.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:5.201ex; height:3.176ex;" alt="{\displaystyle \,{}_{26}^{56}\mathrm {Fe} \,}" loading="lazy"></span>, which is a decay product of <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \,{}_{28}^{56}\mathrm {Ni} \,}">

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<annotation encoding="application/x-tex">{\displaystyle \,{}_{28}^{56}\mathrm {Ni} \,}</annotation>

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</math></span><img src="./744eb653fc3d3be15ca2855fa63d04cb87497007.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:5.04ex; height:3.176ex;" alt="{\displaystyle \,{}_{28}^{56}\mathrm {Ni} \,}" loading="lazy"></span><sup id="cite_ref-:0_2-0" class="reference"><a href="#cite_note-:0-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>) because it is the most tightly bound <a href="Nuclide" title="Nuclide">nuclide</a> – i.e., the nuclide with the highest <a href="Nuclear_binding_energy" title="Nuclear binding energy">nuclear binding energy</a> per <a href="Nucleon" title="Nucleon">nucleon</a> – and production of heavier nuclei would consume energy (be <a href="Endothermic" class="mw-redirect" title="Endothermic">endothermic</a>) instead of release it (<a href="Exothermic" class="mw-redirect" title="Exothermic">exothermic</a>). <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \,{}_{28}^{62}\mathrm {Ni} \,}">

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<annotation encoding="application/x-tex">{\displaystyle \,{}_{28}^{62}\mathrm {Ni} \,}</annotation>

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</math></span><img src="./e78ce7db770b4d2fbd10498ed6592746c4361215.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:5.04ex; height:3.176ex;" alt="{\displaystyle \,{}_{28}^{62}\mathrm {Ni} \,}" loading="lazy"></span> (<a href="Nickel-62" title="Nickel-62">Nickel-62</a>) is actually the most tightly bound nuclide in terms of binding energy<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> (though <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {}^{56}{\textrm {Fe}}}">

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<annotation encoding="application/x-tex">{\displaystyle {}^{56}{\textrm {Fe}}}</annotation>

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</math></span><img src="./248c2b278e177fae3a5106c524d598054c9cdb00.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:4.426ex; height:2.676ex;" alt="{\displaystyle {}^{56}{\textrm {Fe}}}" loading="lazy"></span> has a lower energy or mass per nucleon). The reaction <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {}^{56}{\textrm {Fe}}+{}^{4}{\textrm {He}}\rightarrow {}^{60}{\textrm {Ni}}}">

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<annotation encoding="application/x-tex">{\displaystyle {}^{56}{\textrm {Fe}}+{}^{4}{\textrm {He}}\rightarrow {}^{60}{\textrm {Ni}}}</annotation>

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</math></span><img src="./acae12edc906e8d58be1bb9c9e732f497c3f5228.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.505ex; width:18.977ex; height:2.843ex;" alt="{\displaystyle {}^{56}{\textrm {Fe}}+{}^{4}{\textrm {He}}\rightarrow {}^{60}{\textrm {Ni}}}" loading="lazy"></span> is actually exothermic, and indeed adding alphas continues to be exothermic all the way to <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \ {}_{50}^{100}\mathrm {Sn} \ }">

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<annotation encoding="application/x-tex">{\displaystyle \ {}_{50}^{100}\mathrm {Sn} \ }</annotation>

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</math></span><img src="./b7ee801ca074fb7281859354fe402ce7a9158bf8.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:6.445ex; height:3.176ex;" alt="{\displaystyle \ {}_{50}^{100}\mathrm {Sn} \ }" loading="lazy"></span>,<sup id="cite_ref-AME2020_II_4-0" class="reference"><a href="#cite_note-AME2020_II-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> but nonetheless the sequence does effectively end at iron. The sequence stops before producing elements heavier than nickel because conditions in stellar interiors cause the competition between <a href="Photodisintegration" title="Photodisintegration">photodisintegration</a> and the alpha process to favor photodisintegration around <a href="Iron" title="Iron">iron</a>.<sup id="cite_ref-:0_2-1" class="reference"><a href="#cite_note-:0-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> This leads to more <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \,{}_{28}^{56}\mathrm {Ni} \,}">

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<annotation encoding="application/x-tex">{\displaystyle \,{}_{28}^{56}\mathrm {Ni} \,}</annotation>

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</math></span><img src="./744eb653fc3d3be15ca2855fa63d04cb87497007.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:5.04ex; height:3.176ex;" alt="{\displaystyle \,{}_{28}^{56}\mathrm {Ni} \,}" loading="lazy"></span> being produced than <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \,{}_{28}^{62}\mathrm {Ni} ~.}">

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<annotation encoding="application/x-tex">{\displaystyle \,{}_{28}^{62}\mathrm {Ni} ~.}</annotation>

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</math></span><img src="./41010c98ff1a885d26a0d7d07958107930a22ce7.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:5.881ex; height:3.176ex;" alt="{\displaystyle \,{}_{28}^{62}\mathrm {Ni} ~.}" loading="lazy"></span>

</p><p>All these reactions have a very low rate at the temperatures and densities in stars and therefore do not contribute significant energy to a star's total output. They occur even less easily with elements heavier than <a href="Neon" title="Neon">neon</a> (<span class="nowrap"><span class="texhtml mvar" style="font-style:italic;">Z</span> > 10</span>) due to the increasing <a href="Coulomb_barrier" title="Coulomb barrier">Coulomb barrier</a>.

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<div class="mw-heading mw-heading2"><h2 id="Alpha_process_elements"><span class="anchor" id="Alpha_elements">Alpha process elements</span></h2></div>

<p><b>Alpha process elements</b> (or <b>alpha elements</b>) are so-called since their most abundant isotopes are integer multiples of four – the mass of the helium nucleus (the <a href="Alpha_particle" title="Alpha particle">alpha particle</a>). These isotopes are called <i><a href="Alpha_nuclide" title="Alpha nuclide">alpha nuclides</a></i>.

</p>

<ul><li>The stable alpha elements are: <a href="Carbon" title="Carbon">C</a>, <a href="Oxygen" title="Oxygen">O</a>, <a href="Neon" title="Neon">Ne</a>, <a href="Magnesium" title="Magnesium">Mg</a>, <a href="Silicon" title="Silicon">Si</a>, and <a href="Sulfur" title="Sulfur">S</a>.</li>

<li>The elements <a href="Argon" title="Argon">Ar</a> and <a href="Calcium" title="Calcium">Ca</a> are <i>"<a href="Observationally_stable" class="mw-redirect" title="Observationally stable">observationally stable</a>"</i>. They are synthesized by alpha capture prior to the <a href="Silicon_burning_process" class="mw-redirect" title="Silicon burning process">silicon fusing</a> stage, that leads to <span class="nowrap"><a href="Type_II_supernova" title="Type II supernova">Type II supernovae</a>.</span></li>

<li><a href="Silicon" title="Silicon">Si</a> and <a href="Calcium" title="Calcium">Ca</a> are purely alpha process elements.</li>

<li><a href="Magnesium" title="Magnesium">Mg</a> can be separately consumed by <a href="Proton_capture" title="Proton capture">proton capture</a> reactions.</li></ul>

<p>The status of oxygen (<a href="Oxygen" title="Oxygen">O</a>) is contested – some authors<sup id="cite_ref-:1_6-0" class="reference"><a href="#cite_note-:1-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> consider it an alpha element, while others do not. <a href="Oxygen" title="Oxygen">O</a> is surely an alpha element in low-<a href="Metallicity" title="Metallicity">metallicity</a> <a href="Stellar_population#Population_II_stars" title="Stellar population">Population II stars</a>: It is produced in <a href="Type_II_supernova" title="Type II supernova">Type II supernovae</a>, and its enhancement is well correlated with an enhancement of other alpha process elements.

</p><p>Sometimes <a href="Carbon" title="Carbon">C</a> and <a href="Nitrogen" title="Nitrogen">N</a> are considered alpha process elements since, like <a href="Oxygen" title="Oxygen">O</a>, they are synthesized in nuclear alpha-capture reactions, but their status is ambiguous: Each of the three elements is produced (and consumed) by the <a href="CNO_cycle" title="CNO cycle">CNO cycle</a>, which can proceed at temperatures far lower than those where the alpha-ladder processes start producing significant amounts of alpha elements (including <a href="Carbon" title="Carbon">C</a>, <a href="Nitrogen" title="Nitrogen">N</a>, & <a href="Oxygen" title="Oxygen">O</a>). So just the presence of <a href="Carbon" title="Carbon">C</a>, <a href="Nitrogen" title="Nitrogen">N</a>, or <a href="Oxygen" title="Oxygen">O</a> in a star does not a clearly indicate that the alpha process is actually underway – hence reluctance of some astronomers to (unconditionally) call these three "alpha elements".

</p>

<div class="mw-heading mw-heading2"><h2 id="Production_in_stars">Production in stars</h2></div>

<p>The alpha process generally occurs in large quantities only if the star is sufficiently massive – more massive than about 10 <a href="Solar_mass" title="Solar mass">solar masses</a>.<sup id="cite_ref-:2_7-0" class="reference"><a href="#cite_note-:2-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> These stars contract as they age, increasing core temperature and density to high enough levels to enable the alpha process. Requirements increase with atomic mass, especially in later stages – sometimes referred to as <a href="Silicon-burning_process" title="Silicon-burning process">silicon burning</a> – and thus most commonly occur in <a href="Supernova_nucleosynthesis" title="Supernova nucleosynthesis">supernovae</a>.<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> Type II supernovae mainly synthesize oxygen and the alpha-elements (<a href="Neon" title="Neon">Ne</a>, <a href="Magnesium" title="Magnesium">Mg</a>, <a href="Silicon" title="Silicon">Si</a>, <a href="Sulfur" title="Sulfur">S</a>, <a href="Argon" title="Argon">Ar</a>, <a href="Calcium" title="Calcium">Ca</a>, and <a href="Titanium" title="Titanium">Ti</a>) while <a href="Type_Ia_supernova" title="Type Ia supernova">Type Ia supernovae</a> mainly produce elements of the <a href="Iron_peak" title="Iron peak">iron peak</a> (<a href="Titanium" title="Titanium">Ti</a>, <a href="Vanadium" title="Vanadium">V</a>, <a href="Chromium" title="Chromium">Cr</a>, <a href="Manganese" title="Manganese">Mn</a>, <a href="Iron" title="Iron">Fe</a>, <a href="Cobalt" title="Cobalt">Co</a>, and <a href="Nickel" title="Nickel">Ni</a>).<sup id="cite_ref-:2_7-1" class="reference"><a href="#cite_note-:2-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> Sufficiently massive stars can synthesize elements up to and including the iron peak solely from the hydrogen and helium that initially comprises the star.<sup id="cite_ref-:1_6-1" class="reference"><a href="#cite_note-:1-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup>

</p><p>Typically, the first stage of the alpha process (or alpha-capture) follows from the <a href="Triple-alpha_process" title="Triple-alpha process">helium-burning</a> stage of the star once helium becomes depleted; at this point, free <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {}_{6}^{12}{\textrm {C}}}">

</mrow>

</mrow>

</mrow>

</msubsup>

</mrow>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle {}_{6}^{12}{\textrm {C}}}</annotation>

</semantics>

</math></span><img src="./88aa5889ced31688154bebdd1fba3efc08bec9b9.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:3.554ex; height:3.176ex;" alt="{\displaystyle {}_{6}^{12}{\textrm {C}}}" loading="lazy"></span> capture helium to produce <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {}_{8}^{16}{\textrm {O}}}">

</mrow>

</mrow>

</mrow>

</msubsup>

</mrow>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle {}_{8}^{16}{\textrm {O}}}</annotation>

</semantics>

</math></span><img src="./00e830742934d264c3f23714fd1a329ebf6f934d.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:3.684ex; height:3.176ex;" alt="{\displaystyle {}_{8}^{16}{\textrm {O}}}" loading="lazy"></span>.<sup id="cite_ref-:3_9-0" class="reference"><a href="#cite_note-:3-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> This process continues after the core finishes the helium burning phase as a shell around the core will continue burning helium and <a href="Convection" title="Convection">convecting</a> into the core.<sup id="cite_ref-:2_7-2" class="reference"><a href="#cite_note-:2-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> The second stage (<a href="Neon-burning_process" title="Neon-burning process">neon burning</a>) starts as helium is freed by the photodisintegration of one <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {}_{10}^{20}{\textrm {Ne}}}">

</mrow>

</mrow>

</mrow>

</msubsup>

</mrow>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle {}_{10}^{20}{\textrm {Ne}}}</annotation>

</semantics>

</math></span><img src="./dfe4686c43277aff87cc81a1aeaec0bd1640b9cb.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:4.652ex; height:3.176ex;" alt="{\displaystyle {}_{10}^{20}{\textrm {Ne}}}" loading="lazy"></span> atom, allowing another to continue up the alpha ladder. Silicon burning is then later initiated through the photodisintegration of <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {}_{14}^{28}{\textrm {Si}}}">

</mrow>

</mrow>

</mrow>

</msubsup>

</mrow>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle {}_{14}^{28}{\textrm {Si}}}</annotation>

</semantics>

</math></span><img src="./008b22f57b1aab8d258ee70ffffd3f50209a9389.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:3.816ex; height:3.176ex;" alt="{\displaystyle {}_{14}^{28}{\textrm {Si}}}" loading="lazy"></span> in a similar fashion; after this point, the <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \,{}_{28}^{56}\mathrm {Ni} \,}">

</mrow>

</mrow>

</mrow>

</msubsup>

</mrow>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle \,{}_{28}^{56}\mathrm {Ni} \,}</annotation>

</semantics>

</math></span><img src="./744eb653fc3d3be15ca2855fa63d04cb87497007.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:5.04ex; height:3.176ex;" alt="{\displaystyle \,{}_{28}^{56}\mathrm {Ni} \,}" loading="lazy"></span>peak discussed previously is reached. The <a href="Supernova_remnant" title="Supernova remnant">supernova shock wave</a> produced by stellar collapse provides ideal conditions for these processes to briefly occur.

</p><p>During this terminal heating involving photodisintegration and rearrangement, nuclear particles are converted to their most stable forms during the supernova and subsequent ejection through, in part, alpha processes. Starting at <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {}_{22}^{44}{\textrm {Ti}}}">

</mrow>

</mrow>

</mrow>

</msubsup>

</mrow>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle {}_{22}^{44}{\textrm {Ti}}}</annotation>

</semantics>

</math></span><img src="./288dfa3d0a5cbd9643c4c78f926c0b2a432e4434.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:4.201ex; height:3.176ex;" alt="{\displaystyle {}_{22}^{44}{\textrm {Ti}}}" loading="lazy"></span> and above, all the product elements are radioactive and will therefore decay into a more stable isotope; for instance, <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \,{}_{28}^{56}\mathrm {Ni} \,}">

</mrow>

</mrow>

</mrow>

</msubsup>

</mrow>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle \,{}_{28}^{56}\mathrm {Ni} \,}</annotation>

</semantics>

</math></span><img src="./744eb653fc3d3be15ca2855fa63d04cb87497007.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:5.04ex; height:3.176ex;" alt="{\displaystyle \,{}_{28}^{56}\mathrm {Ni} \,}" loading="lazy"></span> is formed and decays into <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {}_{26}^{56}{\textrm {Fe}}}">

</mrow>

</mrow>

</mrow>

</msubsup>

</mrow>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle {}_{26}^{56}{\textrm {Fe}}}</annotation>

</semantics>

</math></span><img src="./28829eb7d6ae81cbb3d1cd5cc3629eaef95881e3.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:4.426ex; height:3.176ex;" alt="{\displaystyle {}_{26}^{56}{\textrm {Fe}}}" loading="lazy"></span>.<sup id="cite_ref-:3_9-1" class="reference"><a href="#cite_note-:3-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup>

</p>

<div class="mw-heading mw-heading2"><h2 id="Special_notation_for_relative_abundance">Special notation for relative abundance</h2></div>

<p>The abundance of total alpha elements in stars is usually expressed in terms of <a href="Logarithm" title="Logarithm">logarithms</a>, with astronomers customarily using a square bracket notation:

</p>

<mrow>

<mfrac>

<mrow>

</mrow>

</mrow>

</mfrac>

</mrow>

</mrow>

<msub>

</mrow>

</msub>

<msub>

<mrow>

<mrow>

<mfrac>

<msub>

</mrow>

</mrow>

</msub>

<mrow>

<msub>

</mrow>

</msub>

</mrow>

</mfrac>

</mrow>

</mrow>

</mrow>

</mrow>

</msub>

</mrow>

<msub>

</mrow>

</msub>

<msub>

<mrow>

<mrow>

<mfrac>

<msub>

</mrow>

</mrow>

</msub>

<mrow>

<msub>

</mrow>

</msub>

</mrow>

</mfrac>

</mrow>

</mrow>

</mrow>

</mrow>

</msub>

</mrow>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle \left[{\frac {\alpha }{\,{\ce {Fe}}\,}}\right]~\equiv ~\log _{10}{\left(\,{\frac {N_{\mathrm {E} \alpha }}{\,N_{{\ce {Fe}}}\,}}\,\right)_{\mathsf {Star}}}-\log _{10}{\left({\frac {N_{\mathrm {E} \alpha }}{\,N_{{\ce {Fe}}}\,}}\,\right)_{\mathsf {Sun}}}~,}</annotation>

</semantics>

</math></span><img src="./59a36bb6399413226878d728f17b363f22e9a837.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.505ex; width:50.894ex; height:6.176ex;" alt="{\displaystyle \left[{\frac {\alpha }{\,{\ce {Fe}}\,}}\right]~\equiv ~\log _{10}{\left(\,{\frac {N_{\mathrm {E} \alpha }}{\,N_{{\ce {Fe}}}\,}}\,\right)_{\mathsf {Star}}}-\log _{10}{\left({\frac {N_{\mathrm {E} \alpha }}{\,N_{{\ce {Fe}}}\,}}\,\right)_{\mathsf {Sun}}}~,}" loading="lazy"></span></dd></dl>

<p>where <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \,N_{\mathrm {E} \alpha }\,}">

<msub>

</mrow>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle \,N_{\mathrm {E} \alpha }\,}</annotation>

</semantics>

</math></span><img src="./aabbc1677060dc0df2d18f707ce263f1f544fccf.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:5.044ex; height:2.509ex;" alt="{\displaystyle \,N_{\mathrm {E} \alpha }\,}" loading="lazy"></span> is the number of alpha elements per unit volume, and <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \,N_{{\ce {Fe}}}\,}">

<msub>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle \,N_{{\ce {Fe}}}\,}</annotation>

</semantics>

</math></span><img src="./8c5fc336db90d9aa76d884c731ec429722190265.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:4.676ex; height:2.509ex;" alt="{\displaystyle \,N_{{\ce {Fe}}}\,}" loading="lazy"></span> is the number of iron nuclei per unit volume. It is for the purpose of calculating the number <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \,N_{\mathrm {E} \alpha }\,}">

<msub>

</mrow>

</mrow>

</msub>

</mstyle>

</mrow>

<annotation encoding="application/x-tex">{\displaystyle \,N_{\mathrm {E} \alpha }\,}</annotation>

</semantics>

</math></span><img src="./aabbc1677060dc0df2d18f707ce263f1f544fccf.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:5.044ex; height:2.509ex;" alt="{\displaystyle \,N_{\mathrm {E} \alpha }\,}" loading="lazy"></span> that which elements are to be considered "alpha elements" becomes contentious. Theoretical <a href="Galaxy_formation_and_evolution" title="Galaxy formation and evolution">galactic evolution</a> models predict that early in the universe there were more alpha elements relative to iron.

</p>

<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>

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</style><cite id="CITEREFNarlikar1995" class="citation book cs1">Narlikar, Jayant V. (1995). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=0_gmjz-L70EC&pg=PA94"><i>From Black Clouds to Black Holes</i></a>. <a href="World_Scientific" title="World Scientific">World Scientific</a>. p. 94. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-9810220334</bdi>.</cite></span>

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<li id="cite_note-:0-2"><span class="mw-cite-backlink">^ <a href="#cite_ref-:0_2-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-:0_2-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><cite id="CITEREFFewell1995" class="citation journal cs1">Fewell, M.P. (1995-07-01). "The atomic nuclide with the highest mean binding energy". <i>American Journal of Physics</i>. <b>63</b> (7): <span class="nowrap">653–</span>658. <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1995AmJPh..63..653F">1995AmJPh..63..653F</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1119%2F1.17828">10.1119/1.17828</a>. <a href="ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/0002-9505">0002-9505</a>.</cite></span>

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<li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><cite id="CITEREFNave,_Carl_R.c._2017" class="citation web cs1">Nave, Carl R. (c. 2017) [c. 2001]. <a rel="nofollow" class="external text" href="http://hyperphysics.phy-astr.gsu.edu/hbase/NucEne/nucbin2.html#c1">"The most tightly bound nuclei"</a>. Physics and Astronomy. <i>hyperphysics.phy-astr.gsu.edu</i>. HyperPhysics pages. <a href="Georgia_State_University" title="Georgia State University">Georgia State University</a><span class="reference-accessdate">. Retrieved <span class="nowrap">2019-02-21</span></span>.</cite></span>

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<li id="cite_note-AME2020_II-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-AME2020_II_4-0">^</a></b></span> <span class="reference-text"><cite id="CITEREFWangHuangKondevAudi2021" class="citation journal cs1">Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references". <i>Chinese Physics C</i>. <b>45</b> (3): 030003. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1088%2F1674-1137%2Fabddaf">10.1088/1674-1137/abddaf</a>.</cite> </span>

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<li id="cite_note-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-5">^</a></b></span> <span class="reference-text"><cite id="CITEREFBurbidgeBurbidgeFowlerHoyle1957" class="citation journal cs1"><a href="Margaret_Burbidge" title="Margaret Burbidge">Burbidge, E. Margaret</a>; <a href="Geoffrey_Burbidge" title="Geoffrey Burbidge">Burbidge, G.R.</a>; <a href="William_Alfred_Fowler" title="William Alfred Fowler">Fowler, William A.</a>; <a href="Fred_Hoyle" title="Fred Hoyle">Hoyle, F.</a> (1957-10-01). <a rel="nofollow" class="external text" href="https://doi.org/10.1103%2FRevModPhys.29.547">"Synthesis of the elements in stars"</a>. <i>Reviews of Modern Physics</i>. <b>29</b> (4): <span class="nowrap">547–</span>650. <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1957RvMP...29..547B">1957RvMP...29..547B</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1103%2FRevModPhys.29.547">10.1103/RevModPhys.29.547</a></span>.</cite></span>

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<li id="cite_note-:1-6"><span class="mw-cite-backlink">^ <a href="#cite_ref-:1_6-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-:1_6-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><cite id="CITEREFMo2010" class="citation book cs1">Mo, Houjun (2010). <i>Galaxy formation and evolution</i>. Frank Van den Bosch, S. White. Cambridge: Cambridge University Press. p. 460. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-0-521-85793-2</bdi>. <a href="OCLC_(identifier)" class="mw-redirect" title="OCLC (identifier)">OCLC</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/oclc/460059772">460059772</a>.</cite></span>

</li>

<li id="cite_note-:2-7"><span class="mw-cite-backlink">^ <a href="#cite_ref-:2_7-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-:2_7-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-:2_7-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><cite id="CITEREFTruranHeger2003" class="citation cs2">Truran, J.W.; Heger, A. (2003), <span class="id-lock-subscription" title="Paid subscription required"><a rel="nofollow" class="external text" href="https://linkinghub.elsevier.com/retrieve/pii/B0080437516010598">"Origin of the Elements"</a></span>, <i>Treatise on Geochemistry</i>, <b>1</b>, Elsevier: 711, <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2003TrGeo...1....1T">2003TrGeo...1....1T</a>, <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1016%2Fb0-08-043751-6%2F01059-8">10.1016/b0-08-043751-6/01059-8</a>, <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-0-08-043751-4</bdi><span class="reference-accessdate">, retrieved <span class="nowrap">2023-02-17</span></span></cite></span>

</li>

<li id="cite_note-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-8">^</a></b></span> <span class="reference-text"><cite id="CITEREFTruranCowanCameron1978" class="citation journal cs1">Truran, J. W.; Cowan, J. J.; Cameron, A. G. W. (1978-06-01). <a rel="nofollow" class="external text" href="https://doi.org/10.1086%2F182693">"The helium-driven r-process in supernovae"</a>. <i>The Astrophysical Journal</i>. <b>222</b>: <span class="nowrap">L63 –</span> <span class="nowrap">L67</span>. <a href="Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1978ApJ...222L..63T">1978ApJ...222L..63T</a>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1086%2F182693">10.1086/182693</a></span>. <a href="ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/0004-637X">0004-637X</a>.</cite></span>

</li>

<li id="cite_note-:3-9"><span class="mw-cite-backlink">^ <a href="#cite_ref-:3_9-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-:3_9-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><cite id="CITEREFClayton1983" class="citation book cs1">Clayton, Donald D. (1983). <i>Principles of stellar evolution and nucleosynthesis : with a new preface</i>. Chicago: University of Chicago Press. pp. <span class="nowrap">430–</span>435. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>0-226-10953-4</bdi>. <a href="OCLC_(identifier)" class="mw-redirect" title="OCLC (identifier)">OCLC</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/oclc/9646641">9646641</a>.</cite></span>

</li>

</ol></div>

<div class="mw-heading mw-heading2"><h2 id="Further_reading">Further reading</h2></div>

<ul><li><cite id="CITEREFMendelProctorForbes2007" class="citation journal cs1">Mendel, J. Trevor; Proctor, Robert N.; Forbes, Duncan A. (21 August 2007) [31 May 2007]. <a rel="nofollow" class="external text" href="https://doi.org/10.1111%2Fj.1365-2966.2007.12041.x">"The age, metallicity and <span class="texhtml mvar" style="font-style:italic;">α</span>-element abundance of galactic globular clusters, from single stellar population models"</a>. <i>Monthly Notices of the Royal Astronomical Society</i>. <b>379</b> (4) (published 26 July 2007): <span class="nowrap">1618–</span>1636. <a href="ArXiv_(identifier)" class="mw-redirect" title="ArXiv (identifier)">arXiv</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://arxiv.org/abs/0705.4511v2">0705.4511v2</a></span>. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://doi.org/10.1111%2Fj.1365-2966.2007.12041.x">10.1111/j.1365-2966.2007.12041.x</a></span>.</cite></li></ul>

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</style><div id="Nuclear_processes146" style="font-size:114%;margin:0 4em"><a href="Nuclear_reaction" title="Nuclear reaction">Nuclear processes</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Radioactive_decay" title="Radioactive decay">Radioactive decay</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Alpha_decay" title="Alpha decay">Alpha</a></li>

<ul><li><a href="Double_beta_decay" title="Double beta decay">Double</a></li></ul></li>

<li><a href="Gamma_ray" title="Gamma ray">Gamma radiation</a></li>

<li><a href="Cluster_decay" title="Cluster decay">Cluster decay</a></li>

<li><a href="Electron_capture" title="Electron capture">Electron capture</a>

<ul><li><a href="Double_electron_capture" title="Double electron capture">Double</a></li></ul></li>

<li><a href="Internal_conversion" title="Internal conversion">Internal conversion</a></li>

<li><a href="Isomeric_transition" class="mw-redirect" title="Isomeric transition">Isomeric transition</a></li>

<li><a href="Neutron_emission" title="Neutron emission">Neutron emission</a></li>

<li><a href="Positron_emission" title="Positron emission">Positron emission</a></li>

<li><a href="Proton_emission" title="Proton emission">Proton emission</a></li>

<li><a href="Spontaneous_fission" title="Spontaneous fission">Spontaneous fission</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Stellar_nucleosynthesis" title="Stellar nucleosynthesis">Stellar nucleosynthesis</a></th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Deuterium_fusion" title="Deuterium fusion">Deuterium fusion</a></li>

<li><a href="Lithium_burning" title="Lithium burning">Li burning</a></li>

<li><a href="Proton%E2%80%93proton_chain" title="Proton–proton chain">Proton–proton chain</a></li>

<li><a href="CNO_cycle" title="CNO cycle">CNO cycle</a></li>

<li><a href="Triple-alpha_process" title="Triple-alpha process">Triple-α</a></li>

<li><a href="Carbon-burning_process" title="Carbon-burning process">C burning</a></li>

<li><a href="Neon-burning_process" title="Neon-burning process">Ne burning</a></li>

<li><a href="Oxygen-burning_process" title="Oxygen-burning process">O burning</a></li>

<li><a href="Silicon-burning_process" title="Silicon-burning process">Si burning</a></li>

<li><a href="R-process" title="R-process"><i>r</i>-process</a></li>

<li><a href="S-process" title="S-process"><i>s</i>-process</a></li>

<li><a href="P-process" title="P-process">p-process</a></li>

<li><a href="Rp-process" title="Rp-process">rp-process</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other<br>processes</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Photodisintegration" title="Photodisintegration">Photodisintegration</a></li>

<li><a href="Photofission" title="Photofission">Photofission</a></li></ul>

</div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Capture</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Neutron_capture" title="Neutron capture">Neutron capture</a></li>

<li><a href="Proton_capture" title="Proton capture">Proton capture</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Exchange</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="(n-p)_reaction" title="(n-p) reaction">(n-p) reaction</a></li></ul>

</div></td></tr></tbody></table><div>

</div></td></tr></tbody></table></div>

<div class="navbox-styles"></div><div role="navigation" class="navbox" aria-labelledby="Stars520" style="padding:3px"><table class="nowraplinks hlist mw-collapsible mw-collapsed navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div id="Stars520" style="font-size:114%;margin:0 4em"><a href="Star" title="Star">Stars</a></div></th></tr><tr><td class="navbox-abovebelow" colspan="2"><div>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Star_formation" title="Star formation">Formation</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Accretion_(astrophysics)" title="Accretion (astrophysics)">Accretion</a></li>

<li><a href="Molecular_cloud" title="Molecular cloud">Molecular cloud</a></li>

<li><a href="Bok_globule" title="Bok globule">Bok globule</a></li>

<li><a href="Young_stellar_object" title="Young stellar object">Young stellar object</a>

<ul><li><a href="Protostar" title="Protostar">Protostar</a></li>

<li><a href="Pre-main-sequence_star" title="Pre-main-sequence star">Pre-main-sequence</a></li>

<li><a href="Herbig_Ae/Be_star" title="Herbig Ae/Be star">Herbig Ae/Be</a></li>

<li><a href="T_Tauri_star" title="T Tauri star">T Tauri</a></li></ul></li>

<li><a href="Herbig%E2%80%93Haro_object" title="Herbig–Haro object">Herbig–Haro object</a></li>

<li><a href="Hayashi_track" title="Hayashi track">Hayashi track</a></li>

<li><a href="Henyey_track" title="Henyey track">Henyey track</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Stellar_evolution" title="Stellar evolution">Evolution</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Main_sequence" title="Main sequence">Main sequence</a></li>

<li><a href="Red-giant_branch" title="Red-giant branch">Red-giant branch</a></li>

<li><a href="Horizontal_branch" title="Horizontal branch">Horizontal branch</a>

<ul><li><a href="Red_clump" title="Red clump">Red clump</a></li></ul></li>

<li><a href="Asymptotic_giant_branch" title="Asymptotic giant branch">Asymptotic giant branch</a>

<li><a href="Super-AGB_star" title="Super-AGB star">super-AGB</a></li></ul></li>

<li><a href="Planetary_nebula" title="Planetary nebula">Planetary nebula</a>

<ul><li><a href="Protoplanetary_nebula" title="Protoplanetary nebula">Protoplanetary</a></li></ul></li>

<li><a href="Wolf%E2%80%93Rayet_nebula" title="Wolf–Rayet nebula">Wolf–Rayet nebula</a></li>

<li><a href="Dredge-up" title="Dredge-up">Dredge-up</a></li>

<li><a href="Instability_strip" title="Instability strip">Instability strip</a></li>

<li><a href="Luminous_blue_variable" title="Luminous blue variable">Luminous blue variable</a></li>

<li><a href="Stellar_population" title="Stellar population">Stellar population</a></li>

<li><a href="Supernova" title="Supernova">Supernova</a>

<ul><li><a href="Superluminous_supernova" title="Superluminous supernova">Superluminous</a></li>

<li><a href="Hypernova" title="Hypernova">Hypernova</a></li></ul></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Stellar_classification" title="Stellar classification">Classification</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><td colspan="2" class="navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Early-type_star" class="mw-redirect" title="Early-type star">Early</a></li>

<li>Main sequence

<li><a href="Subdwarf" title="Subdwarf">Subdwarf</a>

<li><a href="Subgiant" title="Subgiant">Subgiant</a></li>

<li><a href="Giant_star" title="Giant star">Giant</a>

<li><a href="Yellow_giant" class="mw-redirect" title="Yellow giant">Yellow</a></li></ul></li>

<li><a href="Bright_giant" class="mw-redirect" title="Bright giant">Bright giant</a></li>

<li><a href="Supergiant" title="Supergiant">Supergiant</a>

<li><a href="Yellow_supergiant" title="Yellow supergiant">Yellow</a></li></ul></li>

<li><a href="Hypergiant" title="Hypergiant">Hypergiant</a>

<ul><li><a href="Yellow_hypergiant" title="Yellow hypergiant">Yellow</a></li></ul></li>

<li><a href="Carbon_star" title="Carbon star">Carbon</a>

<li><a href="White_dwarf" title="White dwarf">White dwarf</a></li>

<li><a href="Chemically_peculiar_star" title="Chemically peculiar star">Chemically peculiar</a>

<li><a href="Barium_star" title="Barium star">Barium</a></li>

<li><a href="Lambda_Bo%C3%B6tis_star" title="Lambda Boötis star">Lambda Boötis</a></li>

<li><a href="Technetium_star" title="Technetium star">Technetium</a></li></ul></li>

<ul><li><a href="Shell_star" title="Shell star">Shell</a></li></ul></li>

<li><a href="Helium_star" title="Helium star">Helium</a>

<ul><li><a href="Extreme_helium_star" title="Extreme helium star">Extreme</a></li></ul></li>

<li><a href="Blue_straggler" title="Blue straggler">Blue straggler</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Compact_star" class="mw-redirect" title="Compact star">Remnants</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Compact_star" class="mw-redirect" title="Compact star">Compact star</a></li>

<li><a href="IRAS_00500%2B6713" title="IRAS 00500+6713">Parker's star</a></li>

<li><a href="White_dwarf" title="White dwarf">White dwarf</a>

<ul><li><a href="Helium_planet" title="Helium planet">Helium planet</a></li></ul></li>

<li><a href="Neutron_star" title="Neutron star">Neutron</a>

<ul><li><a href="Radio-quiet_neutron_star" title="Radio-quiet neutron star">Radio-quiet</a></li>

<li><a href="Pulsar" title="Pulsar">Pulsar</a>

<ul><li><a href="Binary_pulsar" title="Binary pulsar">Binary</a></li>

<li><a href="Magnetar" title="Magnetar">Magnetar</a></li></ul></li>

<li><a href="Stellar_black_hole" title="Stellar black hole">Stellar black hole</a></li>

<li><a href="X-ray_binary" title="X-ray binary">X-ray binary</a>

<ul><li><a href="X-ray_burster" title="X-ray burster">Burster</a></li></ul></li>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Hypothetical_star" title="Hypothetical star">Hypothetical</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Blue_dwarf_(red-dwarf_stage)" title="Blue dwarf (red-dwarf stage)">Blue dwarf</a></li>

<li><a href="Black_dwarf" title="Black dwarf">Black dwarf</a></li>

<li><a href="Exotic_star" title="Exotic star">Exotic</a>

<ul><li><a href="Boson_star" class="mw-redirect" title="Boson star">Boson</a></li>

<li><a href="Electroweak_star" class="mw-redirect" title="Electroweak star">Electroweak</a></li>

<li><a href="Strange_star" title="Strange star">Strange</a></li>

<li><a href="Preon_star" class="mw-redirect" title="Preon star">Preon</a></li>

<li><a href="Planck_star" title="Planck star">Planck</a></li>

<li><a href="Dark-energy_star" title="Dark-energy star">Dark-energy</a></li>

<li><a href="Quark_star" title="Quark star">Quark</a></li>

<li>Black hole star

<ul><li><a href="Black_star_(semiclassical_gravity)" title="Black star (semiclassical gravity)">Black</a></li>

<li>Hawking</li>

<li><a href="Quasi-star" title="Quasi-star">Quasi-star</a></li></ul></li>

<li><a href="Gravastar" title="Gravastar">Gravastar</a></li>

<li><a href="Thorne%E2%80%93%C5%BBytkow_object" title="Thorne–Żytkow object">Thorne–Żytkow object</a></li>

<li><a href="Blitzar" title="Blitzar">Blitzar</a></li>

<li><a href="White_hole" title="White hole">White hole</a></li></ul>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Stellar_nucleosynthesis" title="Stellar nucleosynthesis">Nucleosynthesis</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Deuterium_fusion" title="Deuterium fusion">Deuterium burning</a></li>

<li><a href="Lithium_burning" title="Lithium burning">Lithium burning</a></li>

<li><a href="Proton%E2%80%93proton_chain" title="Proton–proton chain">Proton–proton chain</a></li>

<li><a href="CNO_cycle" title="CNO cycle">CNO cycle</a></li>

<li><a href="Helium_flash" title="Helium flash">Helium flash</a></li>

<li><a href="Triple-alpha_process" title="Triple-alpha process">Triple-alpha process</a></li>

<li><a href="Carbon-burning_process" title="Carbon-burning process">C burning</a></li>

<li><a href="Neon-burning_process" title="Neon-burning process">Ne burning</a></li>

<li><a href="Oxygen-burning_process" title="Oxygen-burning process">O burning</a></li>

<li><a href="Silicon-burning_process" title="Silicon-burning process">Si burning</a></li>

<li><a href="S-process" title="S-process">s-process</a></li>

<li><a href="R-process" title="R-process">r-process</a></li>

<li><a href="P-process" title="P-process">p-process</a></li>

<ul><li><a href="Symbiotic_nova" title="Symbiotic nova">Symbiotic</a></li>

<li><a href="Nova_remnant" title="Nova remnant">Remnant</a></li>

<li><a href="Luminous_red_nova" title="Luminous red nova">Luminous red nova</a></li>

<li><a href="Nova#Recurrent_novae" title="Nova">Recurrent</a></li>

<li><a href="Micronova" title="Micronova">Micronova</a></li></ul></li>

<li><a href="Supernova_nucleosynthesis" title="Supernova nucleosynthesis">Supernova</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Stellar_structure" title="Stellar structure">Structure</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li><a href="Convection_zone" title="Convection zone">Convection zone</a>

<ul><li><a href="Microturbulence" title="Microturbulence">Microturbulence</a></li>

<li><a href="Solar-like_oscillations" title="Solar-like oscillations">Oscillations</a></li></ul></li>

<li><a href="Radiation_zone" class="mw-redirect" title="Radiation zone">Radiation zone</a></li>

<li><a href="Stellar_atmosphere" title="Stellar atmosphere">Atmosphere</a>

<ul><li><a href="Photosphere" title="Photosphere">Photosphere</a></li>

<li><a href="Starspot" title="Starspot">Starspot</a></li>

<li><a href="Chromosphere" title="Chromosphere">Chromosphere</a></li>

<li><a href="Stellar_corona" title="Stellar corona">Stellar corona</a></li>

<li><a href="Alfv%C3%A9n_surface" title="Alfvén surface">Alfvén surface</a></li></ul></li>

<li><a href="Stellar_wind" title="Stellar wind">Stellar wind</a>

<ul><li><a href="Stellar-wind_bubble" title="Stellar-wind bubble">Bubble</a></li>

<li><a href="Bipolar_outflow" title="Bipolar outflow">Bipolar outflow</a></li></ul></li>

<li><a href="Accretion_disk" title="Accretion disk">Accretion disk</a>

<ul><li><a href="Protoplanetary_disk" title="Protoplanetary disk">Protoplanetary disk</a></li>

<li><a href="Proplyd" title="Proplyd">Proplyd</a></li></ul></li>

<li><a href="Asteroseismology" title="Asteroseismology">Asteroseismology</a>

<ul><li><a href="Helioseismology" title="Helioseismology">Helioseismology</a></li></ul></li>

<li><a href="Circumstellar_dust" title="Circumstellar dust">Circumstellar dust</a></li>

<li><a href="Cosmic_dust" title="Cosmic dust">Cosmic dust</a></li>

<li><a href="Circumstellar_envelope" title="Circumstellar envelope">Circumstellar envelope</a></li>

<li><a href="Eddington_luminosity" title="Eddington luminosity">Eddington luminosity</a></li>

<li><a href="Kelvin%E2%80%93Helmholtz_mechanism" title="Kelvin–Helmholtz mechanism">Kelvin–Helmholtz mechanism</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Properties</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Stellar_designations_and_names" title="Stellar designations and names">Designation</a></li>

<li><a href="Stellar_dynamics" title="Stellar dynamics">Dynamics</a></li>

<li><a href="Effective_temperature" title="Effective temperature">Effective temperature</a></li>

<li><a href="Luminosity" title="Luminosity">Luminosity</a></li>

<li><a href="Stellar_kinematics" title="Stellar kinematics">Kinematics</a></li>

<li><a href="Stellar_magnetic_field" title="Stellar magnetic field">Magnetic field</a></li>

<li><a href="Absolute_magnitude" title="Absolute magnitude">Absolute magnitude</a></li>

<li><a href="Metallicity" title="Metallicity">Metallicity</a></li>

<li><a href="Stellar_rotation" title="Stellar rotation">Rotation</a>

<ul><li><a href="Gravity_darkening" title="Gravity darkening">Gravity darkening</a></li></ul></li>

<li><a href="Starlight" title="Starlight">Starlight</a></li>

<li><a href="Variable_star" title="Variable star">Variable</a></li>

<li><a href="Photometric_system" title="Photometric system">Photometric system</a></li>

<li><a href="Color_index" title="Color index">Color index</a></li>

<li><a href="Hertzsprung%E2%80%93Russell_diagram" title="Hertzsprung–Russell diagram">Hertzsprung–Russell diagram</a></li>

<li><a href="Color%E2%80%93color_diagram" title="Color–color diagram">Color–color diagram</a></li>

<li><a href="Str%C3%B6mgren_sphere" title="Strömgren sphere">Strömgren sphere</a></li>

<li><a href="Kraft_break" title="Kraft break">Kraft break</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Star_system" title="Star system">Star systems</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Binary_star" title="Binary star">Binary</a>

<ul><li><a href="Contact_binary" title="Contact binary">Contact</a></li>

<li><a href="Common_envelope" title="Common envelope">Common envelope</a></li>

<li><a href="Eclipsing_binary" class="mw-redirect" title="Eclipsing binary">Eclipsing</a></li>

<li><a href="Symbiotic_binary" title="Symbiotic binary">Symbiotic</a></li></ul></li>

<li><a href="Star_system#Multiple_star_systems" title="Star system">Multiple</a></li>

<li><a href="Star_cluster" title="Star cluster">Cluster</a>

<li><a href="Globular_cluster" title="Globular cluster">Globular</a></li>

<li><a href="Super_star_cluster" title="Super star cluster">Super</a></li></ul></li>

<li><a href="Planetary_system" title="Planetary system">Planetary system</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Earth-centric<br>observations</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Solar_eclipse" title="Solar eclipse">Solar eclipse</a></li>

<li><a href="Solar_radio_emission" title="Solar radio emission">Solar radio emission</a></li>

<li><a href="Solar_System" title="Solar System">Solar System</a></li>

<li><a href="Sunlight" title="Sunlight">Sunlight</a></li></ul></li>

<li><a href="Circumpolar_star" title="Circumpolar star">Circumpolar</a></li>

<li><a href="Constellation" title="Constellation">Constellation</a></li>

<li><a href="Asterism_(astronomy)" title="Asterism (astronomy)">Asterism</a></li>

<li><a href="Magnitude_(astronomy)" title="Magnitude (astronomy)">Magnitude</a>

<ul><li><a href="Apparent_magnitude" title="Apparent magnitude">Apparent</a></li>

<li><a href="Extinction_(astronomy)" title="Extinction (astronomy)">Extinction</a></li>

<li><a href="Photographic_magnitude" title="Photographic magnitude">Photographic</a></li></ul></li>

<li><a href="Radial_velocity" title="Radial velocity">Radial velocity</a></li>

<li><a href="Proper_motion" title="Proper motion">Proper motion</a></li>

<li><a href="Stellar_parallax" title="Stellar parallax">Parallax</a></li>

<li><a href="Photometric-standard_star" title="Photometric-standard star">Photometric-standard</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Lists_of_stars" title="Lists of stars">Lists</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="List_of_proper_names_of_stars" title="List of proper names of stars">Proper names</a>

<ul><li><a href="List_of_Arabic_star_names" title="List of Arabic star names">Arabic</a></li>

<li><a href="Chinese_star_names" class="mw-redirect" title="Chinese star names">Chinese</a></li></ul></li>

<li><a href="List_of_star_extremes" title="List of star extremes">Extremes</a>

<ul><li><a href="List_of_most_massive_stars" title="List of most massive stars">Most massive</a></li>

<li><a href="List_of_hottest_stars" title="List of hottest stars">Highest temperature</a></li>

<li><a href="List_of_coolest_stars" title="List of coolest stars">Lowest temperature</a></li>

<li><a href="List_of_largest_stars" title="List of largest stars">Largest volume</a></li>

<li><a href="List_of_smallest_known_stars" title="List of smallest known stars">Smallest volume</a></li>

<li><a href="List_of_brightest_stars" title="List of brightest stars">Brightest</a></li>

<li><a href="Historical_brightest_stars" title="Historical brightest stars">Historical brightest</a></li>

<li><a href="List_of_most_luminous_stars" title="List of most luminous stars">Most luminous</a></li>

<li><a href="List_of_nearest_stars" title="List of nearest stars">Nearest</a>

<ul><li><a href="List_of_nearest_bright_stars" title="List of nearest bright stars">bright</a></li></ul></li></ul></li>

<li><a href="List_of_most_distant_stars" title="List of most distant stars">Most distant</a></li>

<li><a href="List_of_stars_with_resolved_images" title="List of stars with resolved images">With resolved images</a></li>

<li><a href="List_of_multiplanetary_systems" title="List of multiplanetary systems">With multiple exoplanets</a></li>

<li><a href="List_of_brown_dwarfs" title="List of brown dwarfs">Brown dwarfs</a></li>

<li><a href="List_of_red_dwarfs" title="List of red dwarfs">Red dwarfs</a></li>

<li><a href="List_of_white_dwarfs" title="List of white dwarfs">White dwarfs</a></li>

<li><a href="List_of_novae_in_the_Milky_Way_galaxy" title="List of novae in the Milky Way galaxy">Milky Way novae</a></li>

<li><a href="List_of_supernovae" title="List of supernovae">Supernovae</a>

<ul><li><a href="List_of_supernova_candidates" title="List of supernova candidates">Candidates</a></li>

<li><a href="List_of_supernova_remnants" title="List of supernova remnants">Remnants</a></li></ul></li>

<li><a href="List_of_planetary_nebulae" title="List of planetary nebulae">Planetary nebulae</a></li>

<li><a href="Timeline_of_stellar_astronomy" title="Timeline of stellar astronomy">Timeline of stellar astronomy</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Related</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Substellar_object" title="Substellar object">Substellar object</a>

<ul><li><a href="Brown_dwarf" title="Brown dwarf">Brown dwarf</a>

<ul><li><a href="Brown-dwarf_desert" title="Brown-dwarf desert">Desert</a></li>

<li><a href="Planet" title="Planet">Planet</a></li></ul></li>

<li><a href="Galactic_year" title="Galactic year">Galactic year</a></li>

<li><a href="Galaxy" title="Galaxy">Galaxy</a></li>

<li><a href="Guest_star_(astronomy)" title="Guest star (astronomy)">Guest</a></li>

<li><a href="Gravity" title="Gravity">Gravity</a></li>

<li><a href="Intergalactic_star" title="Intergalactic star">Intergalactic</a></li>

<li><a href="Neutron_star_merger" title="Neutron star merger">Neutron star merger</a></li>

<li><a href="Planet-hosting_stars" class="mw-redirect" title="Planet-hosting stars">Planet-hosting stars</a></li>

<li><a href="Stellar_collision" title="Stellar collision">Stellar collision</a></li>

<li><a href="Stellar_engulfment" title="Stellar engulfment">Stellar engulfment</a></li>

<li><a href="Tidal_disruption_event" title="Tidal disruption event">Tidal disruption event</a></li></ul>

</div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div>

<ul><li><span class="noviewer" typeof="mw:File"><span title="Category"></span></span> Category</li>

<li><span class="nowrap"><span class="noviewer" typeof="mw:File"></span> </span><a href="Portal%3AStars" title="Portal:Stars">Stars portal</a></li></ul>

</div></td></tr></tbody></table></div></div><div><div class="zim-footer">

This article is issued from <a class="external text" title="Last edited on 2025-07-16" href="https://en.wikipedia.org/wiki/?title=Alpha_process&oldid=1300861247">Wikipedia</a>. The text is available under <a class="external text" href="https://creativecommons.org/licenses/by-sa/4.0/deed.en">Creative Commons Attribution-Share Alike 4.0</a> unless otherwise noted. Additional terms may apply for the media files.

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