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The distinction between star clusters and associations

Gieles, M and Zwart, SP (2010) The distinction between star clusters and associations Mon. Not. R. Astron. Soc. 410, L6-L7 (2011).

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In Galactic studies a distinction is made between (open) star clusters and associations. For barely resolved objects at a distance of several Mpc this distinction is not trivial to make. Here we provide an objective definition by comparing the age of the stars to the crossing time of nearby stellar agglomerates. We find that a satisfactory separation can be made where this ratio equals unity. Stellar agglomerates for which the age of the stars exceeds the crossing time are bound, and are referred to as star clusters. Alternatively, those for which the crossing time exceeds the stellar age are unbound and are referred to as associations. This definition is useful whenever reliable measurements for the mass, radius and age are available.

Item Type: Article
Divisions : Surrey research (other units)
Authors :
Zwart, SP
Date : 8 October 2010
DOI : 10.1111/j.1745-3933.2010.00967.x
Related URLs :
Depositing User : Symplectic Elements
Date Deposited : 17 May 2017 12:39
Last Modified : 24 Jan 2020 22:37

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