by Ann » Sun Dec 11, 2016 6:00 pm
Chris Peterson wrote:Ann wrote:LL Pegasi is a very interesting object. Amazingly, its spiral has made at least four turns around the center. I can't think of any galaxy that does anything remotely similar.
Of course, there is no reason to make any association between this object and galaxies. Other than a superficial resemblence, the underlying mechanism creating the spiral is entirely different. In this nebula, the material that makes up the spiral arms is actually moving outward- like water from a rotating sprinkler. In a galaxy, nothing is moving outward- that's an illusion like we see with a pinwheel.
Good point, Chris. Of course, I can't help comparing LL Pegasi with a spiral galaxy simply because I'm so fascinated by spiral galaxies.
But LL Pegasi can also be compared with stars, because there are other stars that make pinwheel patterns, like the star (probably
WR 104) at left. I take it that WR 104 (and other
WR stars like it) emit gas that moves outwards, forming spiral patterns. Still, LL Pegasi is outstanding in its regularity.
Ann
[quote="Chris Peterson"][quote="Ann"]LL Pegasi is a very interesting object. Amazingly, its spiral has made at least four turns around the center. I can't think of any galaxy that does anything remotely similar.[/quote]
Of course, there is no reason to make any association between this object and galaxies. Other than a superficial resemblence, the underlying mechanism creating the spiral is entirely different. In this nebula, the material that makes up the spiral arms is actually moving outward- like water from a rotating sprinkler. In a galaxy, nothing is moving outward- that's an illusion like we see with a pinwheel.[/quote]
Good point, Chris. Of course, I can't help comparing LL Pegasi with a spiral galaxy simply because I'm so fascinated by spiral galaxies.
[float=left][img2]http://www.physics.usyd.edu.au/~gekko/pinwheel/movie_11.gif[/img2][c][size=85]Spinning Wolf Rayet star. Source:
https://apod.nasa.gov/apod/ap140603.html[/size][/c][/float] But LL Pegasi can also be compared with stars, because there are other stars that make pinwheel patterns, like the star (probably [url=https://en.wikipedia.org/wiki/WR_104]WR 104[/url]) at left. I take it that WR 104 (and other [url=http://tinyurl.com/zl222su]WR stars[/url] like it) emit gas that moves outwards, forming spiral patterns. Still, LL Pegasi is outstanding in its regularity.
Ann