General astronomy

General astronomy

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General astronomy

Auger transition

Astronomy; General astronomy

A radiationless quantum jump that occurs in the X-ray region. When a K-electron is removed from an atom and an L-electron drops into the vacancy in the K-shell, the energy released in the latter ...

The number of atoms in 12 grams of carbon 12. The number of atoms in a gram-atom (mass in grams numerically equal to the atomic weight) or the number of molecules in a gram-molecule (mass in grams ...

absorption edge

Astronomy; General astronomy

Sudden rises superposed on the smooth decrease of the curve of the attenuation coefficient, which cause the curve to have a typical sawtooth aspect. They generally occur at the limit of spectral ...

absorption line

Astronomy; General astronomy

1) Dark line in a spectrum, produced when light or other electromagnetic radiation coming from a distant source passes through a gas cloud or similar object closer to the observer. Like emission ...

abstraction

Astronomy; General astronomy

a general concept formed by extracting common features from specific examples

acceleration unit

Astronomy; General astronomy

A unit for measuring acceleration, which is metre per second squared.

accretion

Astronomy; General astronomy

1) A process by which a star accumulates matter as it moves through a dense cloud of interstellar gas; or, more generally, whereby matter surrounding a star flows toward it (as in close binaries.) 2) ...