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A phenomenon occurring when a discrete double-excitation state of an atom lies in the ground-state continuum. In the autoionization process one of the excited electrons is ejected, leaving the ion in an excited state (see dielectronic recombination; see also Auger effect). (also called pre-ionization.)
Industry:Astronomy
A hypothetical spin-0 particle with a very small mass of 10-5-10-3 eV. It was postulated in order to provide a natural solution to the "strong CP problem".
Industry:Astronomy
Collapse of mass in such a way that the mass maintains the symmetry of a cylinder.
Industry:Astronomy
1) Angular distance from the north point eastward to the intersection of the celestial horizon with the vertical circle passing through the object and the zenith.
2) Directional bearing around the horizon, measured in degrees from north (0 degree.)
Industry:Astronomy
A measure of the minor axis of an elliptic orbital of an electron according to the Bohr-Sommerfeld theory.
Industry:Astronomy
Decrease in the intensity of radiation, representing energy converted into excitation or ionization of electrons in the region through which the radiation travels. As contrasted with monochromatic scattering (in which reemission occurs in all directions at the same frequency), the inverse process of emission refers to radiation that is reemitted in general in all directions and at all frequencies.
Industry:Astronomy
A nuclear reaction (3 4He → 12C + γ + 7 MeV) by which helium is transformed into carbon. The process is dominant in red giants. At a temperature of about 2 × 108 K and a density of 105 g cm-3, after core hydrogen is exhausted, three α-particles can fuse to form an excited nucleus of carbon 12, which occasionally decays into a stable carbon 12 nucleus. The overall process can be looked upon as an equilibrium between three helium nuclei and the excited 12C*, with occasional irreversible leakage out of the equilibrium into the ground state of carbon 12. Further capture of α-particles by carbon 12 nuclei produces oxygen 16 and neon 20. (also called the triple-α process.)
Industry:Astronomy
