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Nysa family(nÿ -să) A Hirayama family of asteroids containing a single large body ((44) Nysa) about 70 km in diameter and many small objects of 20 km or less. It is associated with the Hertha family; it is thought that (135) Hertha is the core of the parent body and that Nysa is a fragment of the outer mantle. The orbital elements are reasonably dispersed but family members can be easily recognized by their unique colors.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006