Galactic Traffic Patterns 81
eldavojohn writes "Using Hubble, researchers have noticed traffic patterns of stars within our own galaxy. From the article, 'Researchers analyzed 47 Tucanae, the second largest cluster in the Milky Way's galactic neighborhood, and determined the cluster sorts out stars according to their masses. Due to the associated gravitational pull, heavier stars slow down and sink to the cluster's core, while lighter stars pick up speed and zip out to the cluster's periphery.' There is speculation that these movements of stars — although tiny — can have significant implications and possibly result in mass segregation."
I fail to see ... (Score:1)
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Re:I fail to see ... (Score:4, Funny)
-Please don't take this comment seriously.
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2) and not true
3) and not sarcastic.
4) the last line of your post suggests that you are a karma hooker.
You just dont make sense.
Beachballs (light stars) get swong out, and rocks (heavy stars) *do* get sucked in.
Imagine a big roulette table without an outside border or obstacles inside.
Trow in a light ball, it will spin longer.
Trow in a heavy ball, it will drop sooner.
Use constant velocity to trow them in orbit, and not so hard that one or the other will touch the outside in their first orbit
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Re:I fail to see ... (Score:4, Funny)
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Well, that's the obvious expectation if you consider only the interactions between each orbiting star and the center of mass of the galaxy; but their actual motion is a lot more complicated because the you've really got a bunch of non-uniformly distributed objects attracting each other, which is why (b
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Re:I fail to see ... (Score:5, Interesting)
Here, we're looking at stars of different sizes and masses. There aren't some stars made mostly from silicates and iron oxides, while other stars are hollow plastic shells with slightly compressed air cores, or anything like that. A big red giant star may weigh 5x the mass of our sun, but be hundreds or thousands of times more voluminous, so the density as a whole object is actually much lower than a sun sized star.
Also, rocks sink in water. In a pool of mercury. both typical rocks and typical beachballs float. In vaccuum, near a gravitational source, everything that has mass is accelerated at the same rate, and densities really don't matter. Density affets falling objects if there's a drag, like there is falling through air. The space between stars is generally a near perfect vaccuum.
It's significant, because simple, standard physics explanations of sorting by density, type of material, or mass don't entirely explain this. Instead, there are probably other factors such as transfer of momentum between whole groups of stars, perhaps also to gas clouds or something, and maybe even modifying factors such as light pressure or angular momentum-linear momentum exchanges which are in turn affected by such unexpected things as the stars involved's relative surface areas or diameters.
The article talks about slingshot effects. Small stars can be slingshotted a lot faster by the same force that will only moderately accelerate large ones. This in turn means their orbit around the galactic core may even become a parabola or hyperbola, so that any given encounter sometimes becomes their last pass through the cluster. Larger stars get sped up and slowed down, but seldom by all that much, so they tend to keep returning to the cluster.
Sorting out which of these factors, and possibly others, are important and which are trivial is why the people studying this actually have to learn some math.
I have a dream... (Score:5, Funny)
If this keeps up, the stars are gonna be marching on Washington, demanding their equal rights. I have a dream, that someday, all stars will be judged not be mass, but by the content of their cores.
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Of course! (Even though Democrats were the biggest supporters of segregation at the time. You're only allowed to whisper this.)
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A misguided dream (Score:2)
The content of a star's core is determined by its mass. Every star starts out with nothing but hydrogen and has to manufacture everything else. Larger stars burn hotter and can fuse heavier atoms. Some stars explode, spew out stellar matter, and become smaller stars, but this is really their own damn fault. So mass really is the main factor by which stars ought to be segregated. If you think it unfair, build your own univer
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energy conservation? (Score:1)
Re:energy conservation? (Score:4, Informative)
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The basic idea is that we know the shape of the point spread function of hubble extremely well. Since we do know that shape, it's fairly easy to do a cross-colloration and find positions to much better than single-pixel accuracy. Even from the ground it's pretty easy to get positions better than 1/10 of a pixel.
The thumb analogy used above is called parallax (which is often used to determine the distance to nearby stars)
Apathetic bloody planet. (Score:4, Funny)
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Spock, (Score:5, Funny)
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Something at the centre? (Score:3)
Re:Something at the centre? (Score:4, Interesting)
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Er, yeah, so its "only" on the order of the mass of, very roughly, 10^6 average-sized stars.
Can be done without a black hole (Score:2)
Actually, I don't believe you need a massive body at the center of the cluster to cause this to happen. Dynamical friction (due to the gravitational interactions between the stars) could have this effect, with small stars slingshotting off large stars, causing the large stars to loose energy.
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Well, actually, that's how orbits work in general, its just in some cases, one object is massive enough that the "shared center of mass" is not far from the center of mass of the massive object.
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Yes and no. As it happens, we think that most (if not all) galaxies do have massive objects at their cores - but the question is, whether that object was what caused the galaxy to form, or whether it was a byproduct of some other process (for instance, I can see how mass segregation would eventually lead to the formation of a black hole at the core of a galaxy). As someone else has pointed out, in a complex system, the objects can orbit a common center of gravity that is not associated with any one massive
Globular Clusters (Score:2)
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How much money did they waste on THIS?? (Score:2, Insightful)
Offenses . . . (Score:1, Troll)
Where's a cop when you need one? I also would like to take offense to the statement that older, fatter stars move more slowly and drop down. This article is just begging for an intergalactic lawsuit.
Oh, I thought GALACTICA! (Score:2)
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Moo (Score:1)
Keep it moving (Score:2, Funny)
Traffic Report for... Battlestar Galactica? (Score:2)
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how can it? (Score:2)
No WAY! The Pegasus blowed up real good two weeks ago.
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Does this have universal implications? (Score:3, Interesting)
And, if that's so, what would "THE core" be like. Hmmm, black hole not of one star but of entire galaxies?
Which begs the question, is there enough gravitational pull at a hypothetical core of all cores to hold the universe together like a giant counter weight on a pendulum, with fluctuations between expansions and collapses? (Never mind if 'Sha Ka Ree' is really there if it has the mass of 1 million Milky Ways, heh.)
IANA astronomer, astrophysicist, etc. Just curious because from what I read, as go moons, so go solar systems, so go galaxies, so goes the universe.
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I'm guessing that assumes that we can also see everything, which we may possib
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Why the dichotomy? Why must everything either be blown apart forever, or eventually everything sucked back in? Why can the Big Bang/Big Collapse, instead be Big Bang/Not Quite as Big Collapse, as in a damped oscillation? Some material being lost each period, resulting in a smaller bang until the process just wears itself out?
I'm positive that someone smarter that me has postulated such a circumstance, but I've never heard of it. It's always either open or closed, ne
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can even contemplate such questions.
Personnally, as SpaceLifeForm, I have seen no big bang, nor
any collapse. The Universe just exists, is infinite, and
will always exist. Everything else that points to expansion
*or* collapse is just an illusion, physics to confuse the
observer.
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Where do the matching socks to the ones that go into the laundry as a pair and come out as singles end up?
Where are about half of the sets of keys I've owned in my life?
I can think of lots of things that could explain.
too far for gravitational interactions (Score:2)
Another reply pointed out that galaxies behind us are moving away as well. This can be looked at another way though. In order for this effect to happen on the largest scales of the universe, all galaxies must be gravitationally interacting. However, the distances involved are often too great to make such interactions significant. On smaller scales, such as clusters of galaxies, these gravitational interactions are significant, so it is concievable that something similar to what's in the article could occ
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But you only reach equipartition after many
Well, there goes the neighborhood ... (Score:2)
I'm confused (Score:1)
mass segregation (Score:1)
Density? (Score:1)
Binary systems... (Score:1)
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Already Theoretically Predicted (Score:2)
I'm not sure this should come as much of a surprise, given that this has been predicted by dynamical theorey.
It's nice that it's been observed though.
Traffic... (Score:1)
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