Sun, fusion reactions

The sun and all other stars produce energy at a huge rate from sustained nuclear fusion. Over time, stars evolve through several stages, including stellar explosions. The products of a stellar explosion can form stars of more complex composition. Three distinct generations of stars have been identified, each fueled by a different set of fusion reactions. 

Two smaller nuclei can fuse to form a larger nucleus, in what is called a nuclear fusion reaction. You and all other life on Earth would not exist without nuclear fusion reactions. These reactions are the source of the energy produced in the Sun. 

Helium is also the result of fusion reactions wherein the nuclei of heavy hydrogen are fused to form atoms of hehum. The result is the release of great amounts of energy. Fusion is the physical or nuclear reaction (not chemical reaction) that takes place in the sun and in thermonuclear weapons (e.g., the hydrogen bomb). 

The nuclear reactions in which tighter nuclei fuse together to form a heavier nuclear are called nuclear fusion reactions. Such reactions, occur at very high temperature (of the order of > 10 K) which exist only in the sun or interior of stars therefore, such reactions are also called thermonuclear reactions. 

This reaction is a fusion reaction. It shows two light nuclei combining to form one heavy nucleus. This reaction fuels the sun. The two hydrogen reactants are atypical because they re rare isotopes of hydrogen, called tritium and deuterium, respectively. 

Calculate the rate of fusion reactions in the sun. Be sure to correct for the energy loss due to neutrino emission. 

Fusion is what powers the Sun and stars. One type of fusion reaction involves the combination of two "heavy" isotopes of hydrogen. Isotopes of an element have the same number of protons, but a different number of neutrons. For example, hydrogen and its isotopes—deuterium and tritium—all have one proton in their nuclei. Remember that the number of protons plus the number of neutrons make up the mass of an atom. Because they have different numbers of neutrons, hydrogen, deuterium, and tritium have different masses. Deuterium has one proton and one neutron. It has a mass of 2 atomic mass units (amu). Deuterium can also be written as hydrogen-2. The number following the element s name is the isotope s mass. Tritium has one proton and two neutrons. So, tritium has a mass of 3 amu. Tritium can be written as hydrogen-3. 

Fusion reactions, or thermonuclear reactions, release amazing amounts of energy. Inside stars and the Sun, hydrogen atoms are constantly undergoing fusion reactions and giving off energy that we see as light and feel as heat. 

Debris from earlier supemova(s) condensed into the Solar Nebula about 6 billion years ago (Faure, 1998, 22). By about 4.5 billion years ago, the planets had largely condensed from the nebula and the core of the Sun became dense enough to ignite through fusion Reaction 3.1. Based on the chemistry of chondrite meteorites (Wasson and Kallemeyn, 1988, 536), the original Solar Nebula had about 6.79 arsenic atoms for every one million atoms of silicon (Table 3.1) and 2.72 x 1010 atoms of hydrogen (Faure, 1998 Anders and Ebihara, 1982, 15). 

Nuclear fusion reactions occur naturally in the sun for about five billion years. These reactions are the only source of energy sustaining life on our planet. 

Another source of radiation is space. As we know the energy of our sun and all other stars form nuclear fusion reactions. Not only heat and light but also nuclear radiation come to the Earth from space. This nuclear radiation is called cosmic rays or cosmic radiations . The earth s ozone layer usually absorbs these types of radiations. However, a very small quantity of cosmic rays reaches the Earth s surface. Briefly, it is not possible to get rid of radiation. 

Our beloved sun that warms up the Earth from above burns hydrogen in a cycle of fusion reactions that was discovered by Hans Bethe, a German scientist who received the Nobel Prize in physics in 1967 for his understanding of nucleosynthesis in the sun. 

Fusion promises to provide a nearly inexhaustible supply of hydrogen fuel as well as less radioactive waste, but temperatures of fusion reactions are too high for present materials, and the huge amounts of energy needed to start fusion reactions would explode or melt any known construction materials. The fires of nuclear fusion in our Sun provided energy for early humans long before they discovered the art of combustion, see also Chemical Reactions Chemistry and Energy Explosions Fossil Fuels. 

As in nuclear fission, incredible amounts of energy are produced from relatively small amounts of materials. From a raw materials point of view, nuclear fusion is ideal. Hydrogen and helium are readily available fusion reactants. Fusion reactions power the sun, which helps to explain the difficulty in creating the conditions that would allow fusion to take place. The astronomically high temperatures required present technical problems that may never be resolved. 

Bob looks into Miss Muxdroozol s dilated eyes. Let s talk about the Sun. Here are the facts. When we were back on Earth, astronomers had identified more than 60 elements in the Sun s spectrum. The Sun s outer layers had the same ratio of elements that the Sun had when it formed 72 percent hydrogen, 26 percent helium, and 2 percent other elements by weight. However, in the twenty-first century, the Sun s core had around 40 percent helium because some of the hydrogen was converted to helium in nuclear fusion reactions. ... 

Never mind. In the center of the Sun is the core, the Sun s power plant in which nuclear fusion reactions turn hydrogen into helium and generate tremendous amounts of heat. Here, the gas density is more than 100 times that of water, or 14 times that of lead. In fact, the core contains 40 percent of the solar mass. 2 Sir, at that density, why isn t the core a solid ... 

Solar neutrinos, which interact very weakly with matter, should also be produced by the nuclear fusion reactions in the Sun. However, scientist s detect much fewer neutrinos than expected, which may suggest that our knowledge of the solar processes that cause the Sun to shine or of neutrinos themselves is incomplete. 

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