spiral density wave | has definition A wave, due to a local increase in the gravitational field, that produces a series of alternate compressions and rarefactions as it propagates with fixed angular velocity in a rotating galaxy. The compression also acts on interstellar gas in the galaxy, which is triggered to form stars on the leading edges of the spiral arms. The large-scale structure of spiral galaxies can be understood in this way. | ![has source: Silk, J. 1990 The Big Bang, W. H. Publishers, New York, 2001-09-27 09:34:02.0 has source: Silk, J. 1990 The Big Bang, W. H. Publishers, New York, 2001-09-27 09:34:02.0](facet.gif) |
is a kind of galaxy theory | ![2001-09-27 09:34:02.0 2001-09-27 09:34:02.0](facet.gif) |
galaxy theory | has domain extragalactic astronomy | ![2001-09-27 09:34:02.0 2001-09-27 09:34:02.0](facet.gif) |
theory | has validity correct or incorrect with caveats | ![2001-09-27 09:33:53.0 2001-09-27 09:33:53.0](facet.gif) |
has author or reasearch group | ![2001-09-27 09:33:53.0 2001-09-27 09:33:53.0](facet.gif) |
has date or a range of dates for which the theory was active | ![2001-09-27 09:33:53.0 2001-09-27 09:33:53.0](facet.gif) |