Spiral ARMS in Galaxies with Counter-Rotating Stellar Disks

摘要

Spectroscopic observations by Rubin and other indicate that the S type galaxies NGC 4550, NGC 7217, and NGC 4138 have two-way disks with a substantial portion of the stellar disk orbiting opposite the direction of the rest...However, in 1978, Zang and Hohl found via simulations that one-fold instabilities were enhanced in a two-way disk with no halo...Using a self-gravitating disk with a flat rotation curve, we redo Zang and Hohl's isolated simulations but with more particles plus varying amounts of an inert halo component.