Tidal limitation of stellar systems on both circular and elongated orbits

Abstract

Extensive numerical simulations were performed to support a theoretical discussion of first-order tidal limitation of satellites on both circular and elongated orbits in softened external potentials. The existing theory is good for satellites on circular orbits but fails dramatically for noncircular orbits. The mass distribution is much less strongly truncated for elongated orbits than conventionally determined by circular theory applied at pericenter. A new first-order theory for elongated orbits is presented which is in good agreement with the simulations for pericenter not too close to the softened cluster center. For an analytic King model external potential with core radius a-prime, the theory is good down to a pericenter of 3(a-prime). Below this the maximum tide is no longer at pericenter and the theory is inappropriate. Successive passages through pericenter do not noticeably reduce the tidal radius, although continual small mass loss from second-order heating is apparent. The importance of mean field tidal limitation on galaxy evolution in clusters have been overestimated in recent studies. Galaxies on noncircular orbits in clusters are well within their tidal radii even if they pass within one core radius of the center of the cluster. 14 references.