Slashdot Mirror
Galactic Traffic Patterns
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."
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.
Unknown host pong.
All this talk of galactic traffic, and not one mention of the hyperspace bypass.
Slashdot Burying Stories About Slashdot Media Owned
They ... keep ... going ... around ... in ... circles.
Funnypics
It's actually an equiparition of energy thing. Due to all of the gravitational interactions that occur in the cluster, all of the stars should have the same total energy (potential + kinetic). Therefore, at a given area in the cluster, the heavier stars (which are around .80 solar masses) should be moving slower than the lighter stars (which are .2 to .4 solar masses).
The amazing thing is that they were able to determine this by measuring 1/100th of a pixel shifts in Hubble images. Needless to say, it's hard to do astrometry that precisely.
Except in this case the rocks sink slow and the beachballs drop like a rock.
-Please don't take this comment seriously.
You aren't the first one to think of this. From wikipedia, "The galactic center harbours a compact object of very large mass (named Sagittarius A*), strongly suspected to be a supermassive black hole. Most galaxies are believed to have a supermassive black hole at their center."
The simple truth is that interstellar distances will not fit into the human imagination
- Douglas Adams
Duh ! Potatoes aren't designed to sail about the place but ships are.
Rocks sink and beachballs float because of differing densities, not differing masses.
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.
Who is John Cabal?