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Spiral Galaxy Spins the Wrong Way

Posted by chrisd on from the galactic-spirograph dept.

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."

20 of 51 comments (clear)

  1. Wrong way? by SpaceLifeForm · · Score: 2, Interesting

    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.

    --
    You are being MICROattacked, from various angles, in a SOFT manner.
    1. Re:Wrong way? by orangesquid · · Score: 2, Funny

      Yeah! Or, they might just have the photograph upside-down.... ;)

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      --TheOrangeSquid Is it any wonder things seem so awry? We swim in a sea of confusion and don't have to think to survive
    2. Re:Wrong way? by taion · · Score: 3, Insightful

      You should read the article more carefully before you comment next time.

      If you did, you'd clearly have noticed that the article said that the outer spiral arms pointed in the direction that they were rotating, and that was the peculiar aspect of this galaxy, not the actual direction of rotation itself.

      --

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      Floccinaucinihilipilification - the action or habit of judging something to be worthless
    3. Re:Wrong way? by ASCIIMan · · Score: 3, Insightful

      I think the oddity here is that it appears to be spinning counter to the direction its arms are swept, although its rotation could possibly be explained by a collision or combination with another galaxy.

    4. Re:Wrong way? by SpaceLifeForm · · Score: 2, Interesting

      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.

      --
      You are being MICROattacked, from various angles, in a SOFT manner.
    5. Re:Wrong way? by taion · · Score: 5, Informative

      You're continuing to misinterpret the article. The statement was that, for normal galaxies, the spiral arms trail the direction of rotation. That is, if the galaxy itself is rotating "clockwise", the spiral arms trail behind in a "counterclockwise" fashion.

      However, in this case, the spiral arms lead in FRONT of the galaxy's rotation. That is, if the galaxy is rotating "clockwise", the arms stretch forward in the "clockwise" direction; if the galaxy is rotating ccw, the arms also stretch forward ccw!

      The actual direction of rotation of the galaxy is irrelevant, the unexpected fact was the orientation of the spiral arms of the galaxy relative to the galaxy itself. Even in the event of an overlay, the rotation of the spiral arms in the unexpected direction could still be clearly observed.

      In your given case, with two galaxies possessing "normal" behaviour, the arms on both galaxies would trail in the direction of the rotation. If they were spinning in opposite directions, then which arm belonged to which galaxy would be entirely evident through the direction in which the spiral arms were rotating.

      Your objections, then, are entirely groundless.

      But I suppose we can just blame the editors for the vague title.

      --

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      Floccinaucinihilipilification - the action or habit of judging something to be worthless
    6. Re:Wrong way? by kittenslietome · · Score: 4, Informative

      Here is a link to the guy's site--much more information and should be read before anybody starts making-up explanations.

    7. Re:Wrong way? by CheshireCatCO · · Score: 2, Informative

      There is a legitimate question here, and it's the subject of some tricky observing and analysis. You can get the Doppler map of the galaxy, by you need to work out which it is tipping towards you in order to work out if it is a leading or trailing arm spiral. It's hard to say if the "top" of the galaxy is nearer or us or the "bottom" is. If you can't tell that, you can't tell which way it is spinning.

      The usual way of guessing at this it to look for globular clusters. The side that is nearer us will have fewer gobulars in front of it than the farther side. But this is a guess, of course. With a nearly face-on galaxy, this difference is harder to pick out.

  2. CNN Article by Eigenray · · Score: 4, Informative

    CNN has an article with more information.

    1. Re:CNN Article by Telemakhos · · Score: 3, Insightful

      Someone should shoot the CNN editor who came up with the headline: "Goofy galaxy spins the wrong way"

  3. alright by nomadic · · Score: 4, Funny

    I think it's time we wrote our local congresspeople to get this remedied.

  4. ... by questionlp · · Score: 4, Funny

    That galaxy must be in the southern hemisphere of the universe?

  5. Article in The Sun Newspaper Online by Anonymous Coward · · Score: 2, Informative

    The Sun Newspaper Online has a worth and informative article about this discovery in its Science section.

  6. Is it that weird? by CheshireCatCO · · Score: 3, Informative

    I'm a bit confused at why anyone this that this is so bizzaire. Sure, most galaxies are trailing spirals, but there are enough leading spirals to make them not freakish. I'd suspect that it is the spin put on the story by the media, but one astronomer is quoted calling leading-arm spirals extremely rare.

    My take on this is that the real news is the evidence of disruption/interaction. We've seen that before (M51, the Whirlpool, is a good example), but it's still a damned cool thing to see.

  7. More math is needed by Daniel+Dvorkin · · Score: 3, Informative

    Says the math geek, I think this is as much of a mathematical problem as an astronomical one -- i.e., we really don't have a good grasp of the dynamics of galaxy formation, and we won't until the math is there. Classical Newtonian orbital mechanics doesn't do it, of course, since it's an n-body problem with a very, very large value of n. Some new kind of analytical technique needs to be invented before we can say we know much about why galaxies look and move the way they do.

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    The correlation between ignorance of statistics and using "correlation is not causation" as an argument is close to 1.
    1. Re:More math is needed by CheshireCatCO · · Score: 2, Interesting

      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.

    2. Re:More math is needed by alfredw · · Score: 2

      What we really need is more data. Various examinations of the winding problem have been made, and most reasonable solutions lead to very tightly wound spiral arms, if there are any at all. We don't see this, though. We now have this galaxy with arms "trailing" in the same direction as its motion...

      Hopefully we'll be able to take this and turn it into a more accurate model of what a galaxy IS so that we can then figure out why it DOES what it does.

      --
      In Soviet Russia, sig types you!
  8. Re:What this shows.... by CheshireCatCO · · Score: 3, Informative

    You're right up until you state that the core must rotate more quickly. Dark matter has nothing to do with the core of the galaxy or its rotation. And even if the core did rotate rapidly, a la stars about a black hole, so what? There wouldn't be any radial mixing from that, as long as the orbits were Keplerian and nearly circular (which they are, as far as I've heard).

    I also fail to see why this result indicates the presence of dark matter. The direction of rotation should not depend on the dark matter content. This is about how the galaxy formed and how the spiral arms were generated, not about what the galaxy is made of.

  9. Time by sean23007 · · Score: 2, Interesting

    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.

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    Lack of eloquence does not denote lack of intelligence, though they often coincide.
  10. Bizarro Galaxy! by Halloween+Jack · · Score: 2, Funny

    It am Bizarro Galaxy. Everything am different in Bizarro Galaxy. For example, me am happy in job and relationship; am handsome, too.

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    I looked into the abyss, and the abyss looked into me--and we both winked.