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Fusion reactions power the stars and produce all but the lightest elements in a process called nucleosynthesis. Although the fusion of lighter elements in stars releases energy, production of elements heavier than iron absorbs energy.
When the fusion reaction is a sustained uncontrolled chain, it can result in a thermonuclear explosion, such as that generated by a hydrogen bomb. Reactions which are not self-sustaining can still release considerable energy, as well as large numbers of neutrons.
Nucleosynthesis or nucleogenesis is the production of all the chemical elements from the simplest element, hydrogen, by thermonuclear reactions within stars, supernovas, and in the big bang at the beginning of the universe. A star obtains its energy by fusing together light nuclei to form heavier nuclei; in this process, mass (m) is converted into energy (E) in accordance with Einstein's formula, E=mc2, in which cis the speed of light. The reactions are initiated by the high temperatures (about 14 million degrees Celsius) at the center of the star. In the course of producing nuclear energy, the star synthesizes all the elements of the periodic table from its initial composition of mostly hydrogen and a small amount of helium.
Transformation of Hydrogen to Helium
The first step is the fusion of four hydrogen nuclei to make one helium nucleus. This "hydrogen-burning" phase supplies energy to stars on the main sequence of the Hertzsprung-Russell diagram. There are two chains of reactions by which the conversion of hydrogen to helium is effected: the proton-proton cycle and the carbon-nitrogen-oxygen cycle (sometimes referred to simply as the carbon cycle). They were both first studied and proposed as sources of stellar energy by H. Bethe and independently by C. von Weiszäcker. The proton-proton cycle operates in less massive and luminous stars like the sun, while the carbon-nitrogen-oxygen cycle (which speeds up dramatically at higher temperatures) dominates in more massive and luminous stars.
The Proton-Proton Cycle
In the proton-proton cycle, two hydrogen nuclei (protons) are fused and one of these protons is converted to a neutron by beta decay to make a deuterium nucleus (one proton and one neutron). Then a third proton is added to deuterium to form the light isotope of helium, helium-3. When two helium-3 nuclei collide, they form a nucleus of ordinary helium, helium-4 (two protons and two neutrons), and release two protons. In each of these steps considerable energy is also released.
The Carbon-Nitrogen-Oxygen Cycle
The carbon-nitrogen-oxygen cycle requires minute traces of carbon as a catalyst. Four protons are added, one by one, to a carbon nucleus to form a succession of excited (unstable) nuclei of carbon, nitrogen, and oxygen. The intermediate nuclei shed their excess electric charge via beta decay and the final oxygen nucleus spontaneously splits into the original carbon nucleus and a helium-4 nucleus, releasing energy. The net effect is again the combination of four hydrogen nuclei to form one helium-4 nucleus; the carbon is free to begin the cycle over again.
Creation of the Heavier Elements
After the bulk of a star's hydrogen has been converted to helium by either the proton-proton or carbon-nitrogen-oxygen process, the stellar core contracts (while the outer layers expand) until sufficiently high temperatures are reached to initiate "helium-burning" by the triple-alpha process; in this process, three helium nuclei (alpha particles) are fused to make a carbon nucleus. By successive additions of helium nuclei, the heavier elements through iron-56 are built up. The elements whose atomic weights are not multiples of four are created by side reactions that involve neutrons. Because iron-56 is the most stable of the elements, it is very difficult to add an extra helium nucleus to it. However, iron-56 will readily capture a neutron to form the less stable isotope, iron-57. From iron-57, the elements through bismuth-209 can be synthesized. The elements more massive than bismuth-209 are radioactive; that is, they spontaneously break apart. However, during a supernova, an extremely intense flux of neutrons is generated and nuclear reactions proceed so rapidly that the radioactive elements do not have enough time to decay, resulting in the rapid creation of the radioactive elements up to and beyond uranium.
What else can I help you with?
What happens to a stars nuclear energy generation change if the core decreases in temperature?
What happens to a stars nuclear energy generation change if the core decreases in temperature?
How does the energy of the cosmic microwave background compare to the energy radiated by all the stars and galaxies that ever existed?
The energy of the cosmic microwave background is about 400,000 times less than the energy of all the stars and galaxies that ever existed. The CMB is the remnant radiation from the early universe, while the energy radiated by stars and galaxies have been accumulating over millions of years.
How is the production of Star fuel similar to the production of solar energy?
Both the production of Star fuel and solar energy involve harnessing power from natural sources. Star fuel, like solar energy, relies on the energy generated by stars, while solar energy captures the sun's energy using solar panels. Both processes involve converting natural energy sources into usable forms of energy for consumption.
What is the name of the process that converts hydrogen into helium resulting in large amounts of energy within stars?
The process that converts hydrogen into helium within stars, resulting in the release of large amounts of energy, is called nuclear fusion. In the core of stars, hydrogen nuclei fuse under extreme temperature and pressure conditions, producing helium and releasing energy in the form of light and heat. This energy is what powers stars and enables them to shine for billions of years.
Where do all-stars including your sun get their energy from?
Stars get their energy from the nuclear fusion of (primarily) hydrogen into helium, causing a release of binding energy, manifest as thermal energy, light, and radiation in several different forms.
What energy does the sun and stars produce?
the energy sun and stars produce is fusion.
How is nuclear fusion important in stars?
That's how stars get their energy.
How do stars producer light?
Stars get their energy from nuclear fusion.
Can light from stars be turned into energy?
Light from the stars is energy. However, the amount of energy that this light accounts for is too small to be of any use.
Where do stars get energy?
Fusion
What are characteristic of planets?
planets do not shine with their own energy but shine because of energy of stars. they revolve around stars
Stars that generate energy in their cores are called?
Basically all stars do that.
How do stars get their energy?
Nuclear Fusion
What is the nature of the energy emitted by stars?
The energy is called electromagnetic radiation (light energy).
What did Einstein propose about stars?
its not about stars its about mass and he proposed that mass can be converted into energy
How are stars borrn and how do they die?
Stars are born in a Nebula and die by burning out their energy.
Is fusion or fission the main energy source for stars?
Fusion is the main energy source for stars. It is the process by which stars convert hydrogen into helium through nuclear reactions, releasing a tremendous amount of energy in the process. Fission, on the other hand, involves the splitting of atomic nuclei and is not the primary energy source for stars.
