CNO-I cycle The helium nucleus is released at the top-left step. Hydrogen fusion nuclear fusion of four protons to form a helium-4 nucleus  is the dominant process that generates energy in the cores of main-sequence stars.
Most of the copper in pennies and pipes arose in supergiant stars like Rigel and Betelgeuse, say astronomers in Italy. The stars then exploded, casting the copper into space.
The new finding means that gold, silver, and copper all owe their existence to massive stars.
Scientists know the origins of most of the chemical elements from hydrogen to uranium. However, copper atomic number 29 is an exception.
Some theories say the element originated in big stars, while other theories point to stars smaller than the Earth: Their conclusion is noteworthy in part because Matteucci once held the opposite view, that copper arose instead in type Ia supernovae.
When stars die, they eject some of the elements they have created into space, where subsequent generations of stars inherit them. These younger stars thus preserve a record of the deceased stars' nucleosynthesis. Romano and Matteucci compared copper and iron abundances that observers have measured in stars of different ages.
Some of these stars were in the general Milky Way. Others were in Omega Centauri, the Milky Way's most luminous globular star cluster, which may be the nucleus of a small galaxy that smashed into the Milky Way.
Omega Centauri has an unusually low copper-to-iron ratio. As Romano and Matteucci report in a forthcoming issue of Monthly Notices of the Royal Astronomical Society, their models of galactic chemical evolution can explain the data in both locations only if nearly all copper on Earth arose in massive stars--those born with more than eight times the mass of the Sun.
The stars create copper after leaving the main sequence. While on the main sequence, a massive star generates energy by converting hydrogen into helium at its core. It does so through the CNO cycle, in which carbon, nitrogen, and oxygen catalyze the hydrogen-to-helium reaction.
The CNO cycle also changes carbon and oxygen into nitrogen After the star's core runs out of hydrogen, the star expands into a supergiant, and its core begins converting helium into carbon and oxygen.
Helium nuclei also hit the nitrogen, transforming some of it into neon When neon hits helium, it becomes magnesium and liberates a neutron. These neutrons then change some of the iron atomic number 26 that the star acquired at birth into copper.
The flux of neutrons is slow, so astronomers refer to this type of nucleosynthesis as the s-process.
At the end of its life, the star explodes as a type Ib, Ic, or II supernova.We present the first calculations to follow the evolution of all stable nuclei and their radioactive progenitors in stellar models computed from the onset of central hydrogen burning through explosion as Type II supernovae.
Calculations are performed for Pop I stars of 15, 19, 20, 21, and 25M. MASSIVE STARS: PRESUPERNOVA EVOLUTION, EXPLOSION AND NUCLEOSYNTHESIS - from H to Si and eventually explodes as a core collapse supernova. Mup' MPISN Massive stars Mup' MPISN Massive stars Mass Loss (determine which stars explode as RSG and which as BSG) | PowerPoint PPT presentation | free to view.
Evolution and Nucleosynthesis of Massive Stars Alexander Heger Stan Woosley Norbert Langer Tommy Rauscher (massive stars only) Overview • The life of massive stars • The final fates of stars • Nucleosynthesis in massive stars • Neutrino nucleosynthesis • Nuclear .
Stars by A.C. Phillips (Wiley, 2nd edition) is an excellent introduction to the PHYSICS of stars covering basic physics involved in their formation, evolution, and nucleosynthesis.
Stellar Evolution and Nucleosynthesis by S.G. Ryan and A.J. Norton (The Open University and. Nov 18, · In massive stars, the nucleosynthesis by fusion of lighter elements into heavier ones occurs during sequential hydrostatic burning processes .
Stellar nucleosynthesis is the collective term for the nuclear reactions taking place in stars to build the nuclei of the heavier elements.
The processes involved began to be understood early in.