Radially truncated galactic discs

We present the first results of a systematic analysis of radially truncated exponential discs for four galaxies of a complete sample of disc-dominated edge-on spiral galaxies. The discs of our sample galaxies are truncated at similar radii on either s ide of their centres. With the possible exception of the disc of ESO 416-G2 5, it appears that the truncations in our sample galaxies are closely symme tric, in terms of both their sharpness and the truncation length. However, the truncations occur over a larger region and not as abruptly as found in previous studies. We show that the truncated luminosity distributions of our sample galaxies, if also present in the mass distributions, comfortably meet the requiremen ts for longevity. The formation and maintenance of disc truncations are pro bably closely related to stability requirements for galactic discs.