Spiral Galaxy Spins the Wrong Way

Ant writes: "The New Scientist has an article about a galaxy in the constellation Centaurus is puzzling astronomers by spinning in the wrong direction. NGC 4622 has bright twisting arms containing newborn stars and lies 111 million light years away."

Comments

Wrong way?

[SpaceLifeForm]

It could be two galaxies that happen to be lined up from our point of view.
Space can be tricky, there is more there than meets the eye.

Re:Wrong way?

[SpaceLifeForm]

I read the article carefully. My point was that it appears to be strange. If one galaxy is rotating clockwise (from our perspective), and another (either in front or behind but lined up with the first) is rotating counter-clockwise (from our perspective), and at the large distance involved, and the lack of accuracy in measuring such distances, there actually may be nothing strange going on at all. The spiral arms that appear to moving in the unexpected direction may actually belong to the other galaxy than the one that was apparently observed. The article infers that the two galaxies have collided, but they actually could just be close enough to each other to give the observed results. 111,000,000 lightyears is a long way away. I'll not go into gravitational lensing which can throw any galactic observation into doubt.

Reverse Time

[Anonymous Coward]

The flow of time in that part of the universe "backwards" to the flow of time in our part of the universe.

Re:More math is needed

[CheshireCatCO]

The 3-Body problem cannot, in general, be tackle analytically (Poincare showed this). So I am hesitant to believe that we will ever have an analtical technique to directly handle a billion-body problem, like galaxies.

That said, we *do* have analtic techniques to examine galactic dynamics. Lots of 'em, ranging from fluid discriptions to wave approximations. But stunning coinidence, I was just reading Binney and Tremaine, a whole text on galactic dynamics. (The physics is pretty much the same as in planetary rings.) So lots of math exists to tackle these problems. As a math major in astro. grad school, I am pretty confident when I say that the mathematicians won't need to cook up new tools as much as we need to figure out how to apply the existing ones.

The other approach is, of course, various simulation techniques, mainly N-body codes. For that we need
a) Faster computers. We always want faster computers.
b) Better algorithms. This is a place with the Applied Math folks would be really helpful.

What this shows....

[Anonymous Coward]

is that there is more to a galaxy than what we can see, i.e. dark matter. Have you noticed that the time it takes the outside of the galaxy to orbit the core is the same as the inside? Normal physics, assuming what's lit is what we can see, would say that the outside would have to orbit much, much slower to not overpower the galaxy's gravity. But they don't, meaning some other source of mass must be both moving with the arms to keep them up, and providng the gravity necessary to keep them in. Otherwise, the core would rotate very quickly, and you would get what happens when you swirl chocolate milk mix in with milk, it'd blend. Not only does that not happen, but there are barrel-arm galaxies whose arms stick straight out, and now, galaxies whose arms point the direction they're going.

I think this just shows even more convincing evidence for dark matter. By exemplifying this galaxy, we can show that there has to be something else there preventing the arms from "oozing" behind the rotation of the galaxy.

Chocolate milk: explains all, even mysteries of the universe

Time

[sean23007]

Maybe they made a mistake in the measurements, and as they graphed the rotation of the galaxy time was actually going backwards in their simulation. That would yield the results we see now, in a much more humorous (in a slap-yourself-in-the-face kind of) way.