Astrophysics (Index)About

stellar association

(association)
(like a large open cluster but even less tightly bound)

A stellar association is a loose group of stars with the same age, with metallicities, spectral types, and velocities suggesting a common origin. They are presumed to be the result of a recent molecular cloud's star formation, essentially what is left after an open cluster has spread out and mixed somewhat with surrounding stars. Associations that have been identified are generally in nearby portions of the Milky Way and are somewhat young, before the stars have scattered much, and generally form a moving group, a group of stars near each other in position and peculiar velocity, which can be identified through astrometry over time, e.g., with a similar proper motion. The peculiar velocity is generally a necessary identification factor because the associations can overlap within the celestial sphere, and even within the same volume of space. Across the sky, they can be spread over hundreds of square degrees.

It is thought that most stars are in such associations. Associations are often typed by their stellar class (such as OB associations, with both O-type stars and B-type stars), or by other characteristics, such as R associations (i.e., illuminate a reflection nebula) or T associations (i.e., including T-Tauri stars).


(stars,galaxies,star clusters)
Further reading:
https://en.wikipedia.org/wiki/Stellar_association
https://en.wikipedia.org/wiki/Stellar_kinematics#Moving_groups
https://astronomy.swin.edu.au/cosmos/s/Stellar+Association
https://www.daviddarling.info/encyclopedia/A/association_stellar.html

Referenced by pages:
Carina Nebula (NGC 3372)
chemical tagging
Dynamical Analysis of Nearby Clusters (DANCe)
Gaia
Hipparcos
Milky Way (MW)
moving group
OB association
OB star
open cluster (OC)
proper motion (PM)
RAMBO
Scorpius-Centaurus Association (Sco-Cen)
star formation feedback
stellar age determination
stellar cluster (SC)
stellar kinematics
T association
Tucana Horologium association (THA)
TW Hydrae association (TWA)

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