2010/01/29 by J. A. Sellwood, Sellwood, J. A.
Physics and Astronomy · #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #astro-ph.CO
paper · pdf · doi:10.48550/arxiv.1001.5430
Invited review presented at "Evolution of Planetary and Stellar Systems", Prato, Italy. 6 pages, 7 figures, uses emulateapj
arxiv created 2010/01/29 · arxiv updated 2010/02/26
After a short review of the principal theories of spiral structure in galaxies, I describe two new developments. First, it now seems clear that linear theory cannot yield a full description for the development of spiral patterns because N-body simulations suggest that non-linear effects manifest themselves at a relative overdensity of ~2%, which is well below the believed spiral amplitudes in galaxies. Second, I summarize the evidence that some stars in the solar neighborhood have been scattered at an inner Lindblad resonance. This evidence strongly supports a picture of spirals as a recurring cycle of transient instabilities, each caused by resonant scattering by a previous wave.