Talk:Spiral galaxy
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How is it that something that seems so simple can be so complecated? All of our lives are in this galaxies hands and the is nothing that we can do but sit and wait for somthing to happen all over again.--207.12.157.2 15:38, 6 September 2005 (UTC)Sara Huey207.12.157.2 15:38, 6 September 2005 (UTC)
[edit] It's mesmerizing!
i try not to think about it too much cos it can get pretty confusing pretty quick!
[edit] Explanation for Spiral Structure
I'm having some trouble with the proposed explanation for spiral structure in the article, "The first acceptable theory was devised by C. C. Lin and Frank Shu in 1964. They suggested that the spiral arms were manifestations of spiral density waves. They assumed that the stars travel in slightly elliptical orbits and that the orientations of their orbits is correlated, i.e. the ellipses vary in their orientation (one to another) in a smooth way with increasing distance from the galactic center." The diagram illustrates a sequence of concentric ellipses with differing orientations, all centered at the galactic center, and postulates these elipses as the orbits of stars in the galaxy: that the stars orbit in elipses *centered* at the galactic center. But shouldn't eliptical orbits aroung the galactic center have the galactic center at one focus, rather than at the center? Or is the fact that there is a distribution of mass over the whole galaxy, and not just at the center the cause? In any case, I found this point confusing, and I think it merits an explanation. Althai 22:14, 3 October 2006 (UTC)
Interference patterns caused by gravitational waves from two black holes orbiting each other? If the spiral density wave diagram is accurate, then two things must be true. Firstly, the center of mass would have to be elliptical and therefore binary.Secondly, it would have to be rotating,(or it wouldn't be binary for long.) This would have the effect of creating an S-shaped stream of point sources of intense gravity travelling outward (presumably at the speed of light), and tapering off in all directions.It would look much like the stream of water from a sprinkler with two rotating jets. Any mass that comes in contact with the stream, would either give energy to or receive energy from the binary system causing its rotation to speed up and slow down. Each time the "wave" passes the whole system would become more and more balanced. An interesting note is that if enough mass is swept into the arms to overpower the binary system's gravity, it could conceivably start to come apart, creating perhaps a barred spiral, and eventually two galaxies that fly apart. amateur 1 December 2006
