Corrugations in the disk of the edge-on spiral galaxy IC 2233.
MATTHEWS L.D. and USON J.M.
Abstract (from CDS):
We recently reported the discovery of a regular corrugation pattern in the H I disk of the isolated, edge-on spiral galaxy IC 2233. Here we present measurements of the vertical structure of this galaxy at several additional wavelengths, ranging from the far-ultraviolet to the far-infrared. We find that undular patterns with amplitude ≲5" (≲250 pc) are visible in a variety of Population I tracers in IC 2233, including the young to intermediate-age stars, the H II regions, and the dust. However, the vertical excursions become less pronounced in the older stellar populations traced by the mid-infrared light. This suggests that the process leading to the vertical displacements may be linked with the regulation of star formation in the galaxy. We have also identified a relationship between the locations of the density corrugations and small-amplitude (≲5 km/s) velocity undulations in the H I rotation curve. We are able to exclude several possible mechanisms for the origin of the observed corrugations, including tidal interaction from a companion, Parker instabilities, or a galactic bore. Global gravitational instabilities appear to be the most likely explanation, although local perturbations may also be important.