“proper motion”的概念、定义、翻译、参考文献-科学参考

proper motion

Physics

The apparent angular motion of a star on the celestial sphere. This is motion in a direction that is perpendicular to the line of sight.

Astronomy

The progressive change in position of a star due to its motion relative to the Sun. Absolute proper motion is the change in position relative to an inertial reference frame such as that defined by extragalactic objects. Relative proper motion is obtained by measurements relative to selected reference stars at different epochs. The average absolute proper motion of these reference stars is known as the reduction from relative to absolute proper motion. Relative proper motions can be used to separate members of a star cluster from field stars in the same line of sight. Proper motions are usually listed in star catalogues as changes in right ascension and declination per year or century. The star with the largest known proper motion, 10″.36 per year, is Barnard’s Star. See also common proper motion; reduced proper motion.

Geology and Earth Sciences

The apparent movement of a star relative to the other ‘fixed’ stars, at right angles to the observer’s line of sight. For example, Barnard’s star moves 10 seconds of arc per year; this is the largest proper motion recorded. There is no absolute frame of reference, and the positions of stars in the familiar constellations change significantly within a few thousand years.

单词	proper motion
释义	proper motion Physics The apparent angular motion of a star on the celestial sphere. This is motion in a direction that is perpendicular to the line of sight. Astronomy The progressive change in position of a star due to its motion relative to the Sun. Absolute proper motion is the change in position relative to an inertial reference frame such as that defined by extragalactic objects. Relative proper motion is obtained by measurements relative to selected reference stars at different epochs. The average absolute proper motion of these reference stars is known as the reduction from relative to absolute proper motion. Relative proper motions can be used to separate members of a star cluster from field stars in the same line of sight. Proper motions are usually listed in star catalogues as changes in right ascension and declination per year or century. The star with the largest known proper motion, 10″.36 per year, is Barnard’s Star. See also common proper motion; reduced proper motion. Geology and Earth Sciences The apparent movement of a star relative to the other ‘fixed’ stars, at right angles to the observer’s line of sight. For example, Barnard’s star moves 10 seconds of arc per year; this is the largest proper motion recorded. There is no absolute frame of reference, and the positions of stars in the familiar constellations change significantly within a few thousand years.
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