Spiral Galaxy composite
Composite image of spiral galaxy M106 (NGC 4258). Optical data from the Digitized Sky Survey is shown in yellow, radio data from the Very Large Array appears purple, X-ray data from Chandra is coded blue, and infrared data from the Spitzer Space Telescope appears red. The anomalous arms appear as purple and blue emission.
Credits: NASA/CXC/Univ. of Maryland/A.S. Wilson et al. Optical: Pal.Obs. DSS; IR: NASA/JPL-Caltech; VLA & NRAO/AUI/NSF
Mystery spiral arms explained? from ESA
Hubble's view of barred spiral galaxy NGC 1672
How far are galaxies. The Tully-Fisher Relation from Astroprof
Two Trinities and a Very Large Array (VLA) by Daniel @ Cosmic Variance.