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Ring Of Stars Found Around Milky Way

Posted by timothy on from the but-they're-set-on-low dept.

LoPingHo writes "Scientists have found a ring of stars around our galaxy that has previously been undetected due to the faintness of the stars. The article says that it only amounts to 1% of the galaxies mass, but if they are just now finding those, that means there could be even fainter ones there too. Could this be part of the elusive 'dark matter' talked about so much lately?"

8 of 201 comments (clear)

  1. Dark Matter? by ancukiewiczd · · Score: 4, Insightful

    I always thought that dark matter was perfectly invisible, and not just a large number of very dim stars. Maybe those stars could help account for the missing mass, but measuring at 1% it doesn't seem very likely.

    1. Re:Dark Matter? by spanky1 · · Score: 3, Insightful

      I think it is called dark matter because there should be more matter in our galaxy than is currently visible/detectable. But finding more visible matter would seem to reduce the need for as much "dark" matter.

    2. Re:Dark Matter? by pyrrho · · Score: 3, Insightful

      first off, to not pose: I'm a software engineer, not an Astronomer, though my statement of what was "considered less likely" is based on what I've been recently told by astonomers I work with.

      This was an interesting read, though as I said, it was found just through a google search.

      I admit it's all speculation and half of it I don't claim to actually understand to the level of making a good argument.

      But think of a couple things. One, it's not about perfect instruments, it's about instruments that are good enough to see what you are looking for. If I have ten marbles in a dish, but it weighs as much as twenty... I know I should see the extra marbles if they are ordinary marbles. We are not talking about a little bit of missing mass, we are talking about a huge bit of missing mass.

      Another, it's about what you do see. For example, there cannot be a diffuse gas in the galaxies to cause this effect because (a) it would not have enough mass and (b) you could see absorption lines of the gas.

      It's not like we are looking for something small, remember... we're looking for something big! Something with a lot of mass that for some reason doesn't or can't glow.

      And of course I agree that relatively exotic dark matter cannot be the only source of dark matter, some is just undetected baryonic matter. The rub is that it doesn't seem there could be enough of that to account for all the dark matter, a significan portion looks to be something exotic or at least non-baryonic.

      --

      -pyrrho

  2. Re:Not Dark matter by prizzznecious · · Score: 2, Insightful

    Extra mass on the rim alone could not account for the mass discrepancy, but what you're missing is that if scientists couldn't see these stars until now, who knows what else they're missing?

    I mean, these are light-emitting stars, even. What about brown dwarf protostars and even dark clouds of space dust?

    The observation that stars at the edge of our galaxy don't move fast enough shouldn't incite scientists to come up with new types of matter--it should incite them to find the matter that they've obviously overlooked.

    --

    visit the hwky website for a lyrical genius infusion.
  3. more data needed by 1fitz2many · · Score: 2, Insightful

    I didn't notice any mention of velocity data from the article, or what method was used to determine distance. This would be important in understanding the ring's history.

    However, one could speculate that if these stars are indeed part of a ring, the ring may have formed through a collision with another galaxy. For an example, check this out. Here is another example of a ring galaxy.

  4. Re:I don't get it by p3d0 · · Score: 3, Insightful
    I like to give the experts a little credit, and assume that they have ruled these things out already.

    For instance---and this is entirely fictitious---suppose the galaxies appear to be ten times too small to hold together given how fast they are spinning, and so you conclude they must consist of 90% dark matter that is moons and dust and such. Then, suppose you measure the gravitational lensing, and find that the effective mass is only half what it should be if it were 90% moons and dust. Well, you'd probably have to conclude it's only 40% moons and dust, and 50% pure magic.

    That's the kind of thing these scientists do. If someone with actual facts could back me up a bit, I'd appreciate it.

    Regardless, it's easy to dismiss a mystery if you don't know the facts involved.

    --
    Patrick Doyle
    I mod down every jackass who puts his moderation policy in his sig. Oh, wait a sec....
  5. Big Bang Nucleosynthesis by lythari · · Score: 3, Insightful

    Baryonic matter cannot account for dark matter because of big bang nucleosynthesis (BBN). BBN gives us a fairly accurate esimation of the baryonic matter density of the universe. The result derived from BBN agrees with the mean mass density obtained by summing the visible matter from a representative sample of galaxies. Thus this suggests that dark matter is non-baryonic.

  6. Re:I don't get it by Cyno · · Score: 3, Insightful

    Actually I'd probably conclude that my tools for measuring needed to be recalibrated. But I get your point. Personally I'd prefer to explain things with science that everyone can understand. When we talk about the Grand Unification Theory any religious nut, politician, or old person can't possibly understand what dark matter is. The very foundation of their system of beliefs would have to be broken for them to accept the possibility of alternate dimensions, etc. Personally I prefer to believe that its all theory until we have some hard cold facts, and attempt to build an hypothesis based on things that have been proven to exist. But that's just me, and I admit I'm weird. :)