List of creation myths. The following are common categories used to catalog or compare the various creation myths found throughout the world: Basic type[edit] Creation from chaos[edit] Earth diver[edit] Emergence[edit] Ex nihilo (out of nothing)[edit] World Parent[edit] Regional[edit] African[edit] American[edit] Arctic American[edit] Mesoamerican[edit] Mid North American[edit] South American[edit] Asian[edit] Central Asian[edit] East Asian[edit] South Asian[edit] Southeast Asian[edit] European[edit] Middle Eastern[edit] Pacific Islander/Oceanic[edit] References[edit] Leeming, David Adams; Leeming, Margaret Adams (1994).
All-Time Top 3,000 | Wonders in the Dark. Ys. Flight of King Gradlon, by E. V. Luminais, 1884 (Musée des Beaux-Arts, Quimper) Ys (pronounced /ˈiːs/ EESS), also spelled Is or Kêr-Is in Breton, and Ville d'Ys in French (kêr means city in Breton), is a mythical city that was built on the coast of Brittany and later swallowed by the ocean. Most versions of the legend place the city in the Douarnenez Bay. The legend[edit] Origins[edit] According to some versions of the legend, Ys was built below sea level by Gradlon (Gralon in Breton), King of Cornouaille (Kerne in Breton), upon the request of his daughter Dahut (also called Ahes), who loved the sea. In others, Ys was founded more than 2000 years before Gradlon's reign in a then-dry location off the current coast of the Bay of Douarnenez, but the Breton coast had slowly given way to the sea so that Ys was under it at each high tide when Gradlon's reign began.
Fall[edit] Ys was the most beautiful and impressive city in Europe, but quickly became a city of sin under the influence of Dahut. A. Stellar evolution. Representative lifetimes of stars as a function of their masses The life cycle of a Sun-like star. Artist's depiction of the life cycle of a Sun-like star, starting as a main-sequence star at lower left then expanding through the subgiant and giant phases, until its outer envelope is expelled to form a planetary nebula at upper right.
Stellar evolution is the process by which a star undergoes a sequence of radical changes during its lifetime. Depending on the mass of the star, this lifetime ranges from only a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the age of the universe. Nuclear fusion powers a star for most of its life.
Stellar evolution is not studied by observing the life of a single star, as most stellar changes occur too slowly to be detected, even over many centuries. Birth of a star[edit] Schematic of stellar evolution. Protostar[edit] Brown dwarfs and sub-stellar objects[edit] Hydrogen fusion[edit] Nucleosynthesis. Nucleosynthesis is the process that creates new atomic nuclei from pre-existing nucleons, primarily protons and neutrons. The first nuclei were formed about three minutes after the Big Bang, through the process called Big Bang nucleosynthesis. It was then that hydrogen and helium formed that became the content of the first stars, and is responsible for the present hydrogen/helium ratio of the cosmos. With the formation of stars, heavier nuclei were created from hydrogen and helium by stellar nucleosynthesis, a process that continues today. Some of these elements, particularly those lighter than iron, continue to be delivered to the interstellar medium when low mass stars eject their outer envelope before they collapse to form white dwarfs.
The remains of their ejected mass form the planetary nebulae observable throughout our galaxy. Timeline[edit] The subsequent nucleosynthesis of the heavier elements requires the extreme temperatures and pressures of stars and supernovas. Processes[edit] Beta decay. Β− decay in an atomic nucleus (the accompanying antineutrino is omitted). The inset shows beta decay of a free neutron. In both processes, the intermediate emission of a virtual W− boson (which then decays to electron and antineutrino) is not shown. In nuclear physics, beta decay (β decay) is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted from an atomic nucleus. Beta decay is a process which allows the atom to obtain the optimal ratio of protons and neutrons.[1] Beta decay is mediated by the weak force.
There are two types: beta minus and beta plus. In the case of beta decay that produces an electron emission, it is referred to as beta minus (β−), while in the case of a positron emission as beta plus (β+). An example of β− decay is shown when carbon-14 decays into nitrogen-14: 14 6C → 14 7N + e− + ν e Notice how, in electron emission, an electron antineutrino is also emitted. 23 12Mg → 23 11Na + e+ + ν e 81 36Kr + e− → 81 35Br + ν e β− decay[edit]