Gaint shells around elliptical galaxies

NGC 1344
One of the biggest surprises to emerge from the photographic amplification process was the detection of faint shells around otherwise apparently normal (but often isolated) elliptical galaxies. The shells are now believed to be traces of ancient mergers. Many, perhaps most ellipticals accumulate stars in this way, but the evidence is soon smoothed out in the clusters of galaxoes where most elliptical galaxies are found.

Among the first (and best) examples of a 'shell' galaxy was NGC 1344, shown here. This print is from the discovery paper. There were soon many other examples discovered and these were published as a catalogue. One of the more intriguing examples was NGC 3923.
Original plates taken with the UK Schmidt Telescope