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A chart or table of nuclides maps the nuclear, or radioactive, behavior of nuclides, as it distinguishes the isotopes of an element.It contrasts with a periodic table, which only maps their chemical behavior, since isotopes (nuclides that are variants of the same element) do not differ chemically to any significant degree, with the exception of hydrogen.
it is a version without text of the File:Diagram human cell nucleus.svg: Date: 17 jun 2006 (original 27 april 2006) Source: edited with adobe ilustrator: Author: Mariana LadyofHats: Permission (Reusing this file)
For this reason, one or more neutrons are necessary for two or more protons to be bound into a nucleus. As the number of protons increases, so does the ratio of neutrons to protons necessary to ensure a stable nucleus (see graph). For example, although the neutron–proton ratio of 3 2 He is 1:2, the neutron–proton ratio of 238 92 U is ...
When the nucleus has an even number of protons and neutrons, each one of them finds a partner. To excite such a system, one must at least use such an energy as to break a pair. Conversely, in the case of odd number of protons or neutrons, there exists an unpaired nucleon, which needs less energy to be excited.
12 C, a stable isotope of carbon, is abundantly produced in stars due to three factors: The decay lifetime of a 8 Be nucleus is four orders of magnitude larger than the time for two 4 He nuclei (alpha particles) to scatter. [19] An excited state of the 12 C nucleus exists a little (0.3193 MeV) above the energy level of 8 Be + 4 He.
Specifically, for a nucleus of mass number A, the radius r is (approximately) =, where is 1.2 fm. One example of a halo nucleus is 11 Li, which has a half-life of 8.6 ms. It contains a core of 3 protons and 6 neutrons, and a halo of two independent and loosely bound neutrons.
As such, color-color diagrams can be used as a means of representing the stellar population, much like a Hertzsprung–Russell diagram, and stars of different spectral classes will inhabit different parts of the diagram. This feature leads to applications within various wavelength bands.
The spectral class of a star is a short code primarily summarizing the ionization state, giving an objective measure of the photosphere's temperature. Most stars are currently classified under the Morgan–Keenan (MK) system using the letters O, B, A, F, G, K, and M, a sequence from the hottest (O type) to the coolest (M type).