Tag Archives | Astronomy

21 CENTIMETRE LINE

Electromagnetic radiation spectral line of neutral hydrogen atoms. Fine transitions between states in which the spins of the electron and proton are parallel and antiparallel at frequency of 1420 MHz lead to creation of hydrogen spectral line.

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61 CYGNI

Binary star system in the constellation Cygnus. It consists of K-type dwarf stars. Synonyms are Bessel's Star and Piazzi's Flying Star.

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ABERRATION

Phenomenon when the relative motion of observer and light source changes the position of the light source in the field of view of the observer.

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ACCRETION

In astrophysics, accretion refers to growth of a massive object by attracting other matter via gravitational forces.

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ACCRETION DISC

A structure formed by diffuse material in orbital motion around a star or a black hole (central body). Gravitation compresses the material in the disc and induces emission of electromagnetic radiation.

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ACHERNAR

A bright, blue star with six to eight solar masses. The ninth-brightest star in the night sky.

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ACRONYCHAL SETTING

The settings of a star at sunrise.

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ACRONYCHAL. ACRONYCHAL RISING

The rising of stars at sunset.

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ACRUX

The twelfth brightest star in the sky and the brighest star in the constellation Crux.

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ACTIVE GALAXY

A galaxy which emits high quantity of radiation from its center, called active galactic nucleus.

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