Editing Hyades (star cluster) (section)

===Mass segregation===

The observed distribution of stellar types in the Hyades Cluster demonstrates a history of [[Mass segregation (astronomy)|mass segregation]]. With the exception of its white dwarfs, the cluster's central {{Convert|2|pc|abbr=off|spell=in}} contain only star systems of at least {{Solar mass|1}}.<ref name="Perryman" /> This tight concentration of heavy stars gives the Hyades its overall structure, with a core defined by bright, closely packed systems and a halo consisting of more widely separated stars in which later spectral types are common. The core radius is 2.7 parsecs (8.8 light-years, a little more than the distance between the Sun and [[Sirius]]), while the half-mass radius, within which half the cluster's mass is contained, is {{Convert|5.7|pc|abbr=off}}. The tidal radius of {{Convert|10|pc|abbr=off|spell=in}} represents the Hyades' average outer limit, beyond which a star is unlikely to remain gravitationally bound to the cluster core.<ref name="Perryman" /><ref name="Weidemann1992" />

Stellar evaporation occurs in the cluster halo as smaller stars are scattered outward by more massive insiders. From the halo they may then be lost to tides exerted by the Galactic core or to shocks generated by collisions with drifting hydrogen clouds.<ref name="PavaniBica 2007" /> In this way the Hyades probably lost much of its original population of M dwarfs, along with substantial numbers of brighter stars.