ON THE NATURE OF HI SUPERSHELLS AND STELLAR SUPERARCS
Abstract:The old and recent ideas on origin of HI supershells are discussed. The absence of supershells around most suitable clusters is even more enigmatic than the absence of paternal clusters inside most of supershells. The giant stellar arcs of regular shape were generally considered to have been originated from the swept-up gas shell. However their strictly circular shape suggest they were formed owing to the ram pressure to the surface of the infalling clouds. The examples of the star formation in the bow shock, arising due to the supersonic movement of galaxies through the IGM are given to demonstrate the similarity with the arc-shaped stellar complexes in the LMC and NGC 6946. The stellar superarc in NGC 300 was probably formed due to the action of the external blast wave to the HI supercloud in the spiral arm of the galaxy.
Document Type: Research Article
Affiliations: Sternberg Astronomical Institute, Universiteskij pr. 13, Moscow, 119899, Russia
Publication date: January 1, 2002