Using Hubble Space Telescope images to identify straight segments in galaxy nuclear spirals

This Letter reports the discovery of straight segments of nuclear spiral arms. Hubble Space Telescope images of Seyfert galaxies are used. The morphology of the straight features on scales of few hundred parsecs proves to be similar to the morphology of disc-wide polygonal spirals and rings. This suggests that the straight structures on both nuclear and disc scales may have a common physical nature.