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The Universe Adventure - Nucleosynthesis

At this temperature, nucleosynthesis, or the production of light elements, could take place.

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Stellar nucleosynthesis - Revolvy

In modern theory, there are a number of processes which are believed to be responsible for nucleosynthesisin the universe. The majority of these occur within the hot matterinside stars. The successive processes which occurinside stars are known as hydrogen burning (via the or the ), , , , and . Theseprocesses are able to create elements up to iron and nickel, theregion of the isotopes having the highest per nucleon. Heavierelements can be assembled within stars by a neutron capture processknown as the or in explosive environments, such as , by a number of processes. Some ofthe more important of these include the , which involves rapid neutroncaptures, the , which involves rapid proton captures, and the (sometimes knownas the gamma process), which involves of existingnuclei.


The first direct proof that nucleosynthesis occurs in stars wasthe detection of in the atmosphere of a in the early1950s,prototypical for the class of . Because technetium isradioactive, with halflife much less than the age of the star, itsabundance must reflect its creation within that star during itslifetime. Less dramatic, but equally convincing evidence is oflarge overabundances of specific stable elements in a stellaratmosphere. An historically important case was observation ofbarium abundances some 20-50 times greater than in unevolved stars,which is evidence of the operation of the within that star. Many modernproofs appear in the isotopic composition of , solid grains that condensed fromthe gases of individual stars and which have been extracted frommeteorites. Stardust is one component of . The measured isotopiccompositions demonstrate many aspects of nucleosynthesis within thestars from which the stardust grains condensed

Supernova nucleosynthesis within exploding stars by fusing ..

The products of stellar nucleosynthesis are generallydistributed into the universe through mass loss episodes andstellar winds in stars which are of low mass, as in the phase of evolution, as well as through explosive eventsresulting in in the case of massive stars.

This includes ,and produces the elements heavier than iron by an intense burst ofnuclear reactions that typically last mere seconds during theexplosion of the supernova core. In explosive environments ofsupernovae, the elements between silicon and nickel are synthesizedby fast fusion. Also in further nucleosynthesis processescan occur, such as the , in which the most neutron-rich isotopes of elementsheavier than nickel are produced by rapid absorption of free released during theexplosions. It is responsible for our natural cohort of radioactiveelements, such as uranium and thorium, as well as the mostneutron-rich isotopes of each heavy element.

Stellar nucleosynthesis - Wikipedia

occurred within the first three minutes of the beginning of theuniverse and is responsible for much of the abundance ratios of1H (), 2H (), 3He(), and4He (),in the universe .Although 4He continues to be produced by othermechanisms (such as stellar fusion and alpha decay) and traceamounts of 1H continue to be produced by and certaintypes of radioactive decay ( and ), most of the mass of these isotopes in the universe,and all but the insignificant traces of the 3He anddeuterium in the universe produced by rare processes such as , arethought to have been produced in the . The nuclei of these elements, alongwith some 7Li, and 7Be are believed to havebeen formed when the universe was between 100 and 300 seconds old,after the primordial - plasma froze out to form and . Because of the very short period inwhich Big Bang nucleosynthesis occurred before being stopped byexpansion and cooling, no elements heavier than could be formed. (Elements formedduring this time were in the plasma state, and did not cool to thestate of neutral atoms until much later).

'soriginal work on nucleosynthesis of heavier elements in starsoccurred just after World War II. Thiswork attributed production of all heavier elements from in starsduring the nuclear evolution of their compositions, starting fromhydrogen. Hoyle proposed that hydrogen is continuously created inthe universe from vacuum and energy, without need for universalbeginning.

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  • Nucleosynthesis - Universe Today

    The Big Bang Nucleosynthesis theory predicts that roughly 25% the mass ofthe Universe consists of Helium.

  • Supernova nucleosynthesis | Wiki | Everipedia

    Supernova nucleosynthesis is a theory of the production of many different ..

  • Nucleosynthesis | Chemical Elements | Chemogenesis

    The atoms in your body – apart from the hydrogen – were all made in stars … by stellar nucleosynthesis

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A Discussion of Stellar Nucleosynthesis | Answers in …

Nucleosynthesis is the process of creating newatomic nuclei from pre-existing (protons and neutrons). It is thoughtthat the primordial nucleons themselves were formed from the from the as it cooled belowtwo trillion degrees. A few minutes afterward, starting with only and , nuclei up to and (both with mass number 7) wereformed, but only in relatively small amounts. Then the fusionprocess essentially shut down due to drops in temperature anddensity as the universe continued to expand. This first process of may also be called nucleogenesis.

A Discussion of Stellar Nucleosynthesis ..

For this activity, the behavioral objectives are: (1) the students will be able to understand the primary type of nucleosynthetic process that takes place in stars, and (2) the students will be able to write balanced equations for nuclear fusion reactions up to oxygen. This is a card game in which students are dealt seven cards from a deck containing the symbols, in relative proportions, of various isotopes, electrons, neutrons, positrons, and energy. The object is for the student to use the cards in their hand and/or chosen from the deck to form a nuclear fusion reaction. Scores are based on the mass number of each element that is formed. One class period will be allotted for completion and discussion of this activity.

Stellar nucleosynthesis | Space Wiki | FANDOM …

The first ideas on nucleosynthesis were simply that the were created at thebeginnings of the universe, but no successful physical scenario forthis could be identified. Hydrogen and helium were clearly far moreabundant than any of the other elements (all the rest of whichconstituted less than 2% of the mass of the solar system, andpresumably other star systems as well). At the same time it wasclear that carbon was the next most common element, and also thatthere was a general trend toward abundance of light elements,especially those composed of whole numbers of helium-4 nuclei.

Stellar nucleosynthesis refers to the ..

The main activity for this unit will be for each cooperative learning group to prepare and present a fifteen minute power point presentation on a different aspect of the origin of the elements. After briefly presenting the basic foundations of the Big Bang theory and nucleosynthesis, each group will be assigned one of the following topics for their presentation: history of the Big Bang theory, stellar evolution, Big Bang nucleosynthesis, stellar nucleosynthesis, supernova nucleosynthesis, nuclear fusion reactions, and neutron capture reactions. The students will be escorted to the high school library where they will research their topics for two days using both written and electronic resources. The following two days each group will prepare their power point presentation. Presentation and discussion of their work will take place over the last few days of this unit.

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