question: The amounts of elements formed during supernovaes
comment: You are many order of magnitude off with the amounts of element formed in a supernovae. 20 tonnes of uranium is nothing. Just the crust of earth have 40 trillion tonnes of uranium and the crust of earth is 1% of the mass of earth. Humans mine around 60 000 tonnes of uranium per year. & #x200B; In a type II supernovae the star had a initial mass of between 8 and 50 times the mass of the sun and the white dwarf that is left behind have a max mass of 1.4 solar masses. So the mass ejected is 5-48 solar masses. The sun have a mass of 2\*10\^27 tonnes that is 2 octillion tonnes or 2 billion billion billion tonne. & #x200B; If you look at [ URL_1 ]( URL_0 ) wit abundance of elements in the solar system most is hydrogen with 10\^10 compared to 10\^-2 of uranium. So the the solar system is approximate 1/10\^12 uranium If what is ejected from a super nova is similar to the composition of the solar system you would have 2\*10\^27\* 1/10\^12=2\*10\^15 tonnes ejected per solar mass of eject matter. That is 2 quadrillion tonnes or 2 million billion tonnes. So a Type II supernova eject somewhere around 10 million billion of tonnes of uranium. So the numbers in the original post is 15 orders of magnitude off. The answer might be a couple of magnitudes because I do not know if the abundance table is by number of atoms or by mass. If it is buy mass the amount is 200x more.
passages: Supernovae are a major source of elements in the interstellar medium from oxygen through to rubidium, though the theoretical abundances of the elements produced or seen in the spectra varies significantly depending on the various supernova types. Type Ia supernovae produce mainly silicon and iron-peak elements, metals such as nickel and iron. Core collapse supernovae eject much smaller quantities of the iron-peak elements than type Ia supernovae, but larger masses of light alpha elements such as oxygen and neon, and elements heavier than zinc. The bulk of the material ejected by type II supernovae is hydrogen and helium. The heavy elements are produced by: nuclear fusion for nuclei up to S; silicon photodisintegration rearrangement and quasiequilibrium during silicon burning for nuclei between Ar and Ni; and rapid capture of neutrons (r-process) during the supernova's collapse for elements heavier than iron. The r-process produces highly unstable nuclei that are rich in neutrons 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, although neutron star mergers may be the main astrophysical source for many of these elements.
   These injected elements ultimately enrich the molecular clouds that are the sites of star formation. Thus, each stellar generation has a slightly different composition, going from an almost pure mixture of hydrogen and helium to a more metal-rich composition. Supernovae are the dominant mechanism for distributing these heavier elements, which are formed in a star during its period of nuclear fusion. The different abundances of elements in the material that forms a star have important influences on the star's life, and may decisively influence the possibility of having planets orbiting it.
   The Big Bang produced hydrogen, helium, and traces of lithium, while all heavier elements are synthesized in stars and supernovae. Supernovae tend to enrich the surrounding interstellar medium with elements other than hydrogen and helium, which usually astronomers refer to as "metals".
   Section::::Other impacts.
  
  Section::::Other impacts.:Source of heavy elements.
   The abundance of alpha elements in stars is usually expressed in a logarithmic manner:
  
  Here formula_10 and formula_11 are the number of alpha elements and iron nuclei per unit volume. Theoretical galactic evolution models predict that early in the universe there were more alpha elements relative to iron. Type II supernovae mainly synthesize oxygen and the alpha-elements (Ne, Mg, Si, S, Ar, Ca and Ti) while Type Ia supernovae mainly produce elements of the iron peak (Ti, V, Cr, Mn, Fe, Co and Ni) but also alpha-elements.
  
  Section::::External links.
   It is thought that population II stars created all the other elements in the periodic table, except the more unstable ones. An interesting characteristic of Population II stars is that despite their lower overall metallicity, they often have a higher ratio of alpha elements (O, Si, Ne, etc.) relative to Fe as compared to Population I stars; current theory suggests this is the result of Type II supernovae being more important contributors to the interstellar medium at the time of their formation, whereas Type Ia supernova metal enrichment came later in the universe's evolution.
   The abundance of elements in the Solar System is in keeping with their origin from nucleosynthesis in the Big Bang and a number of progenitor supernova stars. Very abundant hydrogen and helium are products of the Big Bang, but the next three elements are rare since they had little time to form in the Big Bang and are not made in stars (they are, however, produced in small quantities by the breakup of heavier elements in interstellar dust, as a result of impact by cosmic rays). Beginning with carbon, elements are produced in stars by buildup from alpha particles (helium nuclei), resulting in an alternatingly larger abundance of elements with even atomic numbers (these are also more stable). In general, such elements up to iron are made in large stars in the process of becoming supernovas. Iron-56 is particularly common, since it is the most stable element that can easily be made from alpha particles (being a product of decay of radioactive nickel-56, ultimately made from 14 helium nuclei). Elements heavier than iron are made in energy-absorbing processes in large stars, and their abundance in the universe (and on Earth) generally decreases with their atomic number.
   In general, elements up to iron are made in large stars in the process of becoming supernovae. Iron-56 is particularly common, since it is the most stable element that can easily be made from alpha particles (being a product of decay of radioactive nickel-56, ultimately made from 14 helium nuclei). Elements heavier than iron are made in energy-absorbing processes in large stars, and their abundance in the universe (and on Earth) generally decreases with increasing atomic number.
  
  Section::::Universe.:Solar system.
   Supernova nucleosynthesis is the nucleosynthesis of chemical elements in supernova explosions. In sufficiently massive stars, the nucleosynthesis by fusion of lighter elements into heavier ones occurs during sequential hydrostatic burning processes called helium burning, carbon burning, oxygen burning, and silicon burning, in which the ashes of one nuclear fuel become, after compressional heating, the fuel for the subsequent burning stage. During hydrostatic burning these fuels synthesize overwhelmingly the alpha-nucleus () products. A rapid final explosive burning is caused by the sudden temperature spike owing to passage of the radially moving shock wave that was launched by the gravitational collapse of the core. W. D. Arnett and his Rice University colleagues demonstrated that the final shock burning would synthesize the non-alpha-nucleus isotopes more effectively than hydrostatic burning was able to do, suggesting that the expected shock-wave nucleosynthesis is an essential component of supernova nucleosynthesis. Together, shock-wave nucleosynthesis and hydrostatic-burning processes create most of the isotopes of the elements carbon (), oxygen (), and elements with (from neon to nickel). As a result of the ejection of the newly synthesized isotopes of the chemical elements by supernova explosions their abundances steadily increased within interstellar gas. That increase became evident to astronomers from the initial abundances in newly born stars exceeding those in earlier-born stars.
   In the modern universe, old asymptotic giant branch (AGB) stars are the dominant source of dust from s-process elements, oxides, and carbon. However, in the early universe, before AGB stars formed, supernovae may have been the main source of dust.
  
  Section::::Other impacts.:Role in stellar evolution.
   These other elements are generated by stellar processes. In astronomy, a "metal" is any element other than hydrogen or helium. This distinction is significant because hydrogen and helium are the only elements that were produced in significant quantities in the Big Bang. Thus, the metallicity of a galaxy or other object is an indication of stellar activity, after the Big Bang.
   The following graph (note log scale) shows the abundance of elements in our Solar System. The table shows the twelve most common elements in our galaxy (estimated spectroscopically), as measured in parts per million, by mass. Nearby galaxies that have evolved along similar lines have a corresponding enrichment of elements heavier than hydrogen and helium. The more distant galaxies are being viewed as they appeared in the past, so their abundances of elements appear closer to the primordial mixture. As physical laws and processes appear common throughout the visible universe, however, scientist expect that these galaxies evolved elements in similar abundance.
   Stars fuse light elements to heavier ones in their cores, giving off energy in the process known as stellar nucleosynthesis. Fusion processes create many of the lighter elements, up to and including iron and nickel in the most massive stars although these mostly remain trapped in stellar cores and remnants. The s-process creates heavy elements, from strontium upwards.
  
  Supernova nucleosynthesis within exploding stars is largely responsible for the elements between oxygen and rubidium: from the ejection of elements produced during stellar nucleosynthesis; through explosive nucleosynthesis during the supernova explosion; and from the r-process (absorption of multiple neutrons) during the explosion.
   Elements heavier than iron, such as gold and lead, are created through elemental transmutations that can only take place in supernovae - as stars begin to fuse heavier elements, substantially less energy is released from each fusion reaction, and each fusion reaction that produces elements heavier than iron is endothermic in nature, and stars are incapable of carrying this out.
   The two lightest elements, hydrogen and helium, were mostly formed in the Big Bang and are the most common elements in the universe. The next three elements (lithium, beryllium and boron) were formed mostly by cosmic ray spallation, and are thus rarer than heavier elements. Formation of elements with from 6 to 26 protons occurred and continues to occur in main sequence stars via stellar nucleosynthesis. The high abundance of oxygen, silicon, and iron on Earth reflects their common production in such stars. Elements with greater than 26 protons are formed by supernova nucleosynthesis in supernovae, which, when they explode, blast these elements as supernova remnants far into space, where they may become incorporated into planets when they are formed.
   Elements heavier than nickel are comparatively rare owing to the decline with atomic weight of their nuclear binding energies per nucleon, but they too are created in part within supernovae. Of greatest interest historically has been their synthesis by rapid capture of neutrons during the "r"-process, reflecting the common belief that supernova cores are likely to provide the necessary conditions. But see the "r"-process below for a recently discovered alternative. The "r"-process isotopes are roughly a 100,000 times less abundant than the primary chemical elements fused in supernova shells above. Furthermore, other nucleosynthesis processes in supernovae are thought to also be responsible for some nucleosynthesis of other heavy elements, notably, the proton capture process known as the "rp"-process, the slow capture of neutrons ("s"-process) in the Helium-burning shells and in the carbon-burning shells of massive stars, and a photodisintegration process known as the "γ"-process (gamma-process). The latter synthesizes the lightest, most neutron-poor, isotopes of the elements heavier than iron from preexisting heavier isotopes.
   Stars with an initial mass up to about 90 times the sun, or a little less at high metallicity, result in a Type II-P supernova, which is the most commonly observed type. At moderate to high metallicity, stars near the upper end of that mass range will have lost most of their hydrogen when core collapse occurs and the result will be a Type II-L supernova. At very low metallicity, stars of around will reach core collapse by pair instability while they still have a hydrogen atmosphere and an oxygen core and the result will be a supernova with Type II characteristics but a very large mass of ejected Ni and high luminosity.
   Type Ia supernovae have a characteristic light curve, their graph of luminosity as a function of time after the explosion. Near the time of maximal luminosity, the spectrum contains lines of intermediate-mass elements from oxygen to calcium; these are the main constituents of the outer layers of the star. Months after the explosion, when the outer layers have expanded to the point of transparency, the spectrum is dominated by light emitted by material near the core of the star, heavy elements synthesized during the explosion; most prominently isotopes close to the mass of iron (iron-peak elements). The radioactive decay of nickel-56 through cobalt-56 to iron-56 produces high-energy photons, which dominate the energy output of the ejecta at intermediate to late times.
   The space between the stars in M87 is filled with a diffuse interstellar medium of gas that has been chemically enriched by the elements ejected from stars as they passed beyond their main sequence lifetime. Carbon and nitrogen are continuously supplied by stars of intermediate mass as they pass through the asymptotic giant branch. The heavier elements from oxygen to iron are produced largely by supernova explosions within the galaxy. Of the heavy elements, about 60% were produced by core-collapse supernovae, while the remainder came from type Ia supernovae. The distribution of oxygen is roughly uniform throughout, at about half of the solar value (i.e., oxygen abundance in the Sun), while iron distribution peaks near the center where it approaches the solar iron value. Since oxygen is produced mainly by core-collapse supernovae, which occur during the early stages of galaxies and mostly in outer star-forming regions, the distribution of these elements suggests an early enrichment of the interstellar medium from core-collapse supernovae and a continuous contribution from Type Ia supernovae throughout the history of M87. The contribution of elements from these sources was much lower than in the Milky Way.
   BULLET::::- How were the chemical elements for life created in massive stars and supernovae?
  
  BULLET::::- How do stars and planetary systems form from dust grains in molecular clouds?
  
  BULLET::::- What is the composition of planetary atmospheres and comets in our Solar System (and beyond)?
  
  Some specific programs include the following:
   In 1996 it was theorized that traces of past supernovae might be detectable on Earth in the form of metal isotope signatures in rock strata. Iron-60 enrichment was later reported in deep-sea rock of the Pacific Ocean. In 2009, elevated levels of nitrate ions were found in Antarctic ice, which coincided with the 1006 and 1054 supernovae. Gamma rays from these supernovae could have boosted levels of nitrogen oxides, which became trapped in the ice.
   The first massive stars died in supernova explosions which ejected heavier elements into the gas, that formed the next generations of stars. The element composition of a star is an indirect indication of the star's generation and its previous star generation.
  
  The mass distribution of the first generation stars is key to understanding the formation of the Universe's structure, chemical enrichment, and large stellar structures like galaxies.
  
  No evidence of supernovae from the very massive first generation stars has been found in the chemical composition of the Milky Way stars.
   The alpha-particle nuclei Ti and those more massive in the final five reactions listed are all radioactive, but they decay after their ejection in supernova explosions into abundant isotopes of Ca, Ti, Cr, Fe and Ni. This post-supernova radioactivity became of great importance for the emergence of gamma-ray-line astronomy.
   Some relatively small quantities of elements beyond helium (lithium, beryllium, and perhaps some boron) were created in the Big Bang, as the protons and neutrons collided with each other, but all of the "heavier elements" (carbon, element number 6, and elements of greater atomic number) that we see today, were created inside stars during a series of fusion stages, such as the proton-proton chain, the CNO cycle and the triple-alpha process. Progressively heavier elements are created during the evolution of a star.
   The Sun is a Population I, or heavy-element-rich, star. The formation of the Sun may have been triggered by shockwaves from one or more nearby supernovae. This is suggested by a high abundance of heavy elements in the Solar System, such as gold and uranium, relative to the abundances of these elements in so-called Population II, heavy-element-poor, stars. The heavy elements could most plausibly have been produced by endothermic nuclear reactions during a supernova, or by transmutation through neutron absorption within a massive second-generation star.
  