Size of the Milky Way Upgraded, Solving Galaxy Puzzle

[n2doc]

The disk of the Milky Way Galaxy disk may actually be rippled.



Two ringlike structures of stars wrapping around the Milky Way's outer disk now appear to belong to the disk itself.

The results, outlined in a new study, show that the disk is about 60 percent larger than previously thought. Not only do the results extend the size of the Milky Way, they also reveal a rippling pattern, which raises intriguing questions about what sent wavelike fluctuations rippling through the disk.

The researchers said the likely culprit was a dwarf galaxy. It might have plunged through the Milky Way's center long ago, sparking the rippling patterns astronomers have now detected for the first time. [When Galaxies Collide: Photos of Great Galactic Crashes]

Roughly 15 years ago, Heidi Newberg, an astronomer at the Rensselaer Polytechnic Institute in New York, and her colleagues found a group of stars beyond the disk's outermost edge. The so-called Monoceros Ring is about 60,000 light-years from the galactic center (just beyond where the disk was thought to end at 50,000 light-years).

more
http://www.space.com/29270-milky-way-size-larger-than-thought.html

[eppur_se_muova]

1. Doesn't *every* spiral or barred spiral have these density waves ??

Why propose a special "catastrophism"-type mechanism for such a common feature ?

That still leaves us No. 2 behind Andromeda, BTW. (GOP blames Obama in 3 ... 2 ... )