A tidal shock occurs when a
star cluster or other distributed
astronomical object passes by a large mass
such as an
interstellar cloud, resulting in
gravitational perturbation on a time scale that is much less than the mean time for a star to complete an orbit within the cluster. The
tidal force from this event can increase the dynamic energy of the cluster, in effect heating it up. This causes the cluster to expand and shed some of the outer stars.[1]
Tidal shocks occur, for example, when a
globular cluster passes through the galactic plane or near the core of the
Milky Way. These events are an important factor during the early evolution of a globular cluster. They work to truncate the outer part of clusters, thereby limiting the impact of future tidal shocks.[2] Streams of stars shed from a globular cluster as a result of tidal shock can form what are termed
tidal tails. These are extended streams of stars that lead away from the cluster.[3] Such streams can be used to trace the orbital path of the cluster.[4]
^Lee, Hyung Mok (March 12–16, 2001). "The Life and Death of Globular Clusters". Written at Pucon, Chile. In D. Geisler; E.K. Grebel; D. Minniti (eds.). Extragalactic Star Clusters, IAU Symposium 207. San Francisco:
Astronomical Society of the Pacific (published 2002).
Bibcode:
2002IAUS..207..584L.