Neutral hydrogen in the interacting pair NGC 4725/NGC 4747

Neutral hydrogen observations of the galaxy pair NGC4725/NGC4747, a subsystem within the Coma I cloud, reveal severe distortion in the HI distribution of NGC 4747. The ridge of the HI emission within that galaxy deviates from the optical major axis by about 300 and appears to coincide with a faint optical appendage. The companion NGC 4725, a supergiant spiral, is the most prominent member of the Coma I cloud and is almost twenty times more massive than its neighbor. NGC 4725 itself shows small but noticeable perturbations. A tidal encounter is invoked in order to explain the catastrophic events which have led to the distortion of NGC 4747 and the formation of its HI and optical tail