Initial Tidal Effects of Shell Formation

Sharp edged features have been observed by Malin and Carter (1980), Schweizer (1980) and others in the envelopes of many elliptical galaxies. The most promising of current models involves the disruption of a low mass galaxy penetrating close to the centre of a considerably larger ellipsoidal galaxy (Schweizer, 1980, Quinn, 1984, Hernquist and Quinn, 1986, Dupraz and Combes, 1986). The release of stars having a range of energies and with a definite relationship between velocity and position at the point of release generates sharp features by the "phase wrapping" mechanism. The authors examine this effect using a self-consistent particle-mesh code to follow the disruption phase in an almost radial encounter. A standard 2-body code continues the integration up to a Hubble time.