The giant and supergiant shells of the Magellanic Clouds

Abstract

A process of high contrast printing and unsharp masking has been applied to two long exposure H<it>α</it> + [N <scp>II</scp>] plates of the LMC and one of the SMC. Thirty-two new giant (20–260 pc diameter) interstellar shells have been discovered in the LMC. Also two new supergiant (≃ 1000 pc diameter) shells have been certainly revealed and three tentatively identified in the LMC. In all, nine supergiant shells in the LMC and one in the SMC could exist. The formation and statistics of all these phenomena are discussed and their relationship to the young spiral arms of the LMC considered.