peculiar motion

peculiar motion

1. The motion of an individual star relative to a group of neighboring stars.

2. That part of the proper motion of a star that results from its actual movement in space; it is the star's proper motion after elimination of the effects of the Sun's motion.

3. (peculiar velocity; streaming motion) A deviation of a galaxy or cluster of galaxies from the Hubble flow due to its real motion under local gravitational effects, such as the motion of the Local Group due to the Great Attractor.

Collins Dictionary of Astronomy © Market House Books Ltd, 2006