Definition

Noun: - The velocity of an astronomical object relative to the local standard of rest: In astronomy, "peculiar velocity" refers to the motion of a star, galaxy, or other celestial body relative to the average motion of nearby objects in its local region of space. It is the component of the object's total velocity that remains after subtracting the velocity due to the general expansion of the universe (the Hubble flow).

Usage Examples

• Noun:
  • Astronomers must account for a galaxy's peculiar velocity to measure its true distance using redshift.
  • The Sun has a peculiar velocity of about 370 km/s relative to the local standard of rest.

Advanced Usage

• "Peculiar velocity field": A map or description of the distribution of peculiar velocities for a group of galaxies, often used to study gravitational influences like the Great Attractor.
  • The peculiar velocity field revealed large-scale flows of galaxies.

Variants and Related Words

• Peculiar motion (n): A synonymous term for peculiar velocity, emphasizing the motion itself rather than its speed and direction.
  • The peculiar motion of the star was difficult to isolate.

Synonyms

• Anomalous velocity: A less common synonym highlighting the deviation from the expected Hubble flow.
• Proper motion: A related but distinct concept; proper motion is the angular change in position of a star across the sky, while peculiar velocity is the true physical speed in three-dimensional space relative to a local reference frame.

Related Phrases

• Peculiar velocity dispersion: A statistical measure of the spread or variation in peculiar velocities within a cluster of galaxies.
  • The high peculiar velocity dispersion indicated a massive galaxy cluster.

Noun

1. velocity with respect to the local standard of rest