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The falling off of the energy density of radiation with distance from the source, or with passage through an absorbing or scattering medium.
Industry:Astronomy
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
1) A measure of the intrinsic brightness of a star or galaxy. Absolute magnitude is defined as the apparent magnitude the star or galaxy would have if it were 32.6 light-years (10 parsecs) from Earth. The lower an object's absolute magnitude, the greater its intrinsic brightness. For example, the Sun has an absolute magnitude of +4.83, while Sirius, whose intrinsic brightness is greater, has an absolute magnitude of +1.43. A star that is one absolute magnitude brighter than another (e.g., +4 versus +5) is 2.5 times intrinsically brighter; a star that is 5 absolute magnitudes brighter is 100 times intrinsically brighter; and a star that is 10 absolute magnitudes brighter is 10000 times intrinsically brighter.
2) The absolute magnitude (g) of a solar-system body such as an asteroid is defined as the brightness at zero phase angle when the object is 1 AU from the Sun and 1 AU from the observer.
Industry:Astronomy
Temperature measured on the Kelvin scale: 0 Kelvin = -273.15 degree Celsius. Absolute temperature is directly related to (kinetic) energy via the equation E = kBT, where kB is Boltzmann's constant. So, a temperature of 0 K corresponds to zero energy, and room temperature, 300 K = 27 degree, corresponds to an energy of 0.025 eV.
Industry:Astronomy
