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Astro*Dictionary by Michael Erlewine





6 articles for "Stellar"

Stellar Aberration [Astro*Index]

One of the components of planetary aberration, caused by a displacement (disp) toward the apex of the motion of the observer. The net effect of aberration is that stars appear to move on small Aberrational Ellipses about their geometrical ("true") positions, making a full circuit in one year. Such aberrational orbits vary with the Celestial Latitude: A star near the pole of the Ecliptic follows a (nearly) circular path of radius 20.47", while a star on the Ecliptic seems to oscillate in a straight light about its "true" position, with stars at intermediate latitudes following elliptical paths.

It is given by: disp = (V/c) sin theta where V/c = relative velocity of the observer and theta is angle between the geometric position of the body and the direction of the observer's motion.

See also: ♦ Light-time Correction ♦ Planetary Aberration ♦ Aberration ♦ Celestial Latitude ♦ Ecliptic
Stellar Diameter [Astro*Index]

Literally the diameter of a star. This can seldom be directly observed, but can be calculated using such factors as color, temperature, spectral analysis, etc.

See also: ♦ Stars ♦ Spectral Class
Stellar Evolution [Astro*Index]

The life cycle of a star, from Protostar to Main Sequence, then to Red Giant, and, finally, to White Dwarf, Black Dwarf, or stellar relic. This sometimes includes more spectacular stages, such as Nova, Supernova, and Black Hole.

See also: ♦ Red Giant ♦ Protostar ♦ Main Sequence ♦ Nova ♦ Supernova ♦ White Dwarf ♦ Black Dwarf
Stellar Magnitude [Astro*Index]

An obsolete system in which magnitude was obtained by comparison of apparent magnitude to certain standard stars.

See also: ♦ Apparent Magnitude
Stellar Mass [Astro*Index]

The mass of a star, expressed in relationship to that of the Sun. Stars commonly range from about 0.1 to 10 solar masses.

See also: ♦ Stars
Stellar Rotation [Astro*Index]

The rotation of a star on its axis. Our Sun's period of rotation is about 25 days. Younger stars generally exhibit faster periods of rotation then older stars.

See also: ♦ Stars ♦ Axis


Astro*Index Copyright © 1997 Michael Erlewine


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