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Star Cluster Ejected From Galaxy At 2,000,000 MPH

Posted by Soulskill on from the get-out-and-stay-out dept.

William Robinson writes: "According to a new report, a globular cluster of several thousand stars (compressed into a space just a few dozen light-years apart) is being thrown out of galaxy M87. The cluster, named HVGC-1, is traveling at a rate of 2 million miles per hour. The discovery was made by Nelson Caldwell of the Harvard-Smithsonian Center for Astrophysics and his team while studying the space around the supergiant elliptical galaxy M87. Caldwell and colleagues think M87 might have two supermassive black holes at its center. The star cluster wandered too close to the pair, which picked off many of the cluster's outer stars while the inner core remained intact. The black holes then acted like a slingshot, flinging the cluster away at a tremendous speed."

34 of 133 comments (clear)

  1. Velocity by dtmos · · Score: 5, Interesting

    Two million miles per hour is less than 0.003c, but still quite a clip, even in astronomical terms.

    Since they're discussing velocity (vector speed), and not just speed, the headline is correct in saying " -1000 km/s" when the measured value is -1025 km/s, but one can debate whether the abstract is correct in saying "an extraordinary blueshift of -1025 km/s", rather than "an extraordinary blueshift of 1025 km/s", since "blueshift" gives one the sign of the velocity already.

    1. Re:Velocity by KrackerJax · · Score: 3, Interesting

      It would take a ship travelling at that speed roughly two days to travel from Earth to the Sun (1 AU). In those terms it doesn't seem all that fast. Pedestrian, really.

      --
      Sauer
    2. Re:Velocity by pr0t0 · · Score: 5, Interesting

      I wonder if the Earth was in orbit around a star that was part of such a cluster, would we notice the effects of such an ejection? Certainly the night sky would change, but the whole process could take of millions of years. Would we feel any immediate effects from the proximity to the black holes? What would our current state of technology, instrumentation and measurement tell us about our relative place and speed? And what, if any change would there be in our civilization's future. Not being in the galaxy seems isolating, but if the host star remains unchanged perhaps there is no change in our destiny. Or perhaps that by the time we developed interstellar travel we'd be too far from the host galaxy to travel to anything other than the stars in our cluster.

      It'd make for a good sci-fi book I think.

      --
      I'm sorry, but your opinion seems to be wrong.
    3. Re:Velocity by Anonymous Coward · · Score: 5, Funny

      Only on Slashdot is a speed of 2*10^^6 MPH
      1) expressed in imperial units
      2) called "pedestrian" by some poster
      Good stuff.

    4. Re:Velocity by LeadSongDog · · Score: 4, Funny

      So that would be 48.5 megaSmoot/semester, based on the conventional 39 hour semester

      --
      Oh, I'm sorry sir, I thought you were referring to me, Mr. Wensleydale.
    5. Re:Velocity by skastrik · · Score: 5, Interesting

      Frederik Pohl's The World at the End of Time deals with the ejections of solar systems on a grand scale.

    6. Re:Velocity by meta-monkey · · Score: 2

      IANAA, but I would not be shocked to learn that being anywhere close enough to a black hole to cause this galactic ejection would mean sterilization via gamma radiation from the other matter being ripped apart and then colliding with other matter in the accretion disk. There are so many high-energy events going on near a black hole that irradiation seems very likely to me.

      --
      We don't have a state-run media we have a media-run state.
    7. Re:Velocity by FatdogHaiku · · Score: 2

      Only on Slashdot is a speed of 2*10^^6 MPH
      1) expressed in imperial units
      2) called "pedestrian" by some poster
      Good stuff.

      1) You won't be dissing those "imperial units" once the Death Star is finished!
      2) I have it on good authority that everything is already moving at 12,000,000 a minute so yes, 2 million miles an HOUR does seem "pedestrian".

      I'll save you the trouble on the numbers:
      http://en.wikipedia.org/wiki/Galaxy_Song

      --
      You have the right to remain sentient. If you give up the right to remain sentient, you will be elected to public office
    8. Re:Velocity by gewalker · · Score: 2

      I'm sure all would be happier if this were expressed in more familiar units

      555.55 miles per sec
      894.08 kilometers per sec
      2300 times the muzzle velocity of a S&W 40 cal bullet
      2600 times the speed of sound
      2.1 E4 times the speed of a fastball
      8.7 e4 times the speed of Usain Bolt
      2 e13 times the speed of grass growing
      5.376 E9 furlongs per for fortnight

    9. Re:Velocity by butalearner · · Score: 2

      More relevantly, with a whole lot of calculus and some really interesting tech advances, this might provide an example of how to do some STL intergalactic travel.

      No no no, you (and another guy just a little ways down) haven't made the most interesting connection yet. This is a fancy gravity assist on steroids, but it would still take millions if not billions of years to get to even one of Milky Way's satellite galaxies, let alone Andromeda. So forget about intergalactic travel for now. Where this becomes more immediately interesting is finding pairs of very close, very large gravity wells within the same galaxy. That makes them into something rather like Mass Effect relays. Just wait for the proper alignment and launch toward the opposite pair at very high speeds, which can only be canceled by a similar gravity well. Alpha Centauri is a binary star system but the stars are quite far away, so I doubt it would work there, which is too bad since something relatively close like that would have been nice for us. Gliese 667 is a triple star system where the two larger ones are 12.6 AU apart, so that's a much better but still might not be close enough (I don't know, haven't done any math).

  2. Reads like a TMZ.com headline by bazmail · · Score: 2

    If Star Cluster was a rap posse and Galaxy was a club.

  3. If it's not too much to ask by Arancaytar · · Score: 5, Funny

    Could we please use real scientific units when talking about science?

    How much is this in libraries of congress per fortnight?

    1. Re:If it's not too much to ask by stewsters · · Score: 5, Funny

      Remember that 1 lightyear = 1.03461597 × 1014 American football fields.

    2. Re:If it's not too much to ask by stewsters · · Score: 2

      The superscript didn't work. edit: 10 ^ 14

    3. Re:If it's not too much to ask by K.+S.+Kyosuke · · Score: 2

      Hey, I'm European. We don't have those imperial units here. How much Romes per day is one Library of Congress per fortnight?

      --
      Ezekiel 23:20
    4. Re:If it's not too much to ask by man-element · · Score: 2

      Hey, I'm European. We don't have those imperial units here. How much Romes per day is one Library of Congress per fortnight?

      Roughly 8 million olympic size swimming pools per menstrual cycle.

  4. They didn't pay the rent? by tekrat · · Score: 4, Interesting

    A cluster of stars were "thrown out" of galaxy M87?... what, they didn't pay the rent? Or is M87 expressing a case of "tough love"?

    The real question is; by what force were they ejected from the galaxy? The fastest we've ever been about to propel something is 24,000 mph -- and that's with a lot of gravity assists.... if we could figure out how to get a spacecraft to 2 million mph, trips around our solar system would go a lot faster.....

    --
    If telephones are outlawed, then only outlaws will have telephones.
    1. Re:They didn't pay the rent? by jfdavis668 · · Score: 3, Funny

      It was an old, run down section of the galaxy.

    2. Re:They didn't pay the rent? by CanHasDIY · · Score: 5, Funny

      It was an old, run down section of the galaxy.

      So, what are you trying to say? That black holes only live in the galactic ghetto?

      Racist.

      --
      An enigma, wrapped in a riddle, shrouded in bacon and cheese
    3. Re:They didn't pay the rent? by CreatureComfort · · Score: 4, Informative

      Nah, at a constant 1 G acceleration you could get to 2 M mph in under 51 hours.

      --
      "Unheard of means only it's undreamed of yet,
      Impossible means not yet done." ~~ Julia Ecklar
    4. Re:They didn't pay the rent? by ultranova · · Score: 2

      At that point, the velocity needs to be computed through general relativity, which is fiendishly more complicated than just v/a.

      Actually, it's just v = c*tanh(a*T/c).

      --

      Forget magic. Any technology distinguishable from divine power is insufficiently advanced.

  5. Slingshot effect by Anonymous Coward · · Score: 3, Funny

    "The black holes then acted like a slingshot, flinging the cluster away at a tremendous speed."

    ... and then the star cluster went back in time and saved the whales from extinction.

  6. Can anyone explain... by mark-t · · Score: 2

    ... if two spaceships counterclockwise in a circular path such that they are always on opposite side of the circle at relativistic speeds, looking out of the window at the other spaceship, because it appears to be travelling in the opposite direction, its speed is going to appear to be $\sqrt{2*v^2}/c$, and its clock should appear to be going more slowly than your own, right? So if both spaceships perceive that the other's clock is moving more slowly, what will they perceive if the spaceships come together to compare clocks? Will the clock on the other ship suddenly appear to be going faster than normal?

    --
    File under 'M' for 'Manic ranting'
    1. Re:Can anyone explain... by wonkey_monkey · · Score: 3, Interesting

      You say it "appears to be travelling in the opposite direction," but does it? It never gets any closer or any further away. Both ships are travelling around a common center, but relative to each other, are they in fact (as far as time dilation is concerned) stationary?

      So if both spaceships perceive that the other's clock is moving more slowly, what will they perceive if the spaceships come together to compare clocks?

      You can simplify (or in the light my above thought, perhaps even "make valid") this particular question a bit by considering the twin paradox instead. The same thing happens - the twin who stays at home considers the travelling twin's clock to be slower, but so does the traveller. And it's the same on the home trip, too, even though the traveller is now moving towards the stay-at-home. What breaks the symettry of the situation is that only one of them undergoes acceleration at the start, turnaround, and end points.

      If the traveller had stayed at Alpha Centauri and his lazy twin had ventured out to follow him at the same speed, their clocks would match.

      I suspect that the same applies to the circling ships - the clocks will match if neither breaks symmetry, otherwise they won't. And if the symmetry break is done only at non-relativistic speeds - i.e., both twins slow to a stop, then one tootles over to the other at 10km/h - the clocks will practically match.

      --
      systemd is Roko's Basilisk.
    2. Re:Can anyone explain... by bjorniac · · Score: 4, Informative

      Well, there are a few things that would have to happen for them to compare clocks, and a key thing you're overlooking in your analysis:

      1) For circular motion, the two ships would not have constant velocity in their _own_ reference frames - they're both accelerating towards the center (I'm assuming a flat space-time here for simplicity, but in GR things don't change much). Acceleration causes time dilation too!

      2) For the ships to come together, they would have to maneouver. This will require further accelerations. Its during these that the other ship's clock will always appear to be moving faster.

      What you've really got here is a reworking of the classical twin paradox - if one twin goes to Alpha Centauri (AC) and back, and the other stays on Earth, from _each_ perspective, the other one moves away then comes back. Yet the one who went to AC and back comes back younger - why? Well, what you're missing is that _at_ AC you have to slow down and then accelerate back towards Earth. This is the missing segment of the space-time picture, as the surfaces of simultaneity change during this acceleration.

      I hope that clarifies things a bit.

  7. 2 million miles an hour ? by aepervius · · Score: 2

    Why not just use per second (I won't even harp on using 900 km.s-1 at that point it seems neigh useless) and compare to speed of light (that's about 0.3% of speed of light by the way) or other astronomical measurement.

    --
    C. Sagan : A demon haunted world:
    http://www.amazon.com/gp/product/0345409469/
    visit randi.org
  8. For the last time by Lucas123 · · Score: 3, Funny

    Don't come back!

  9. Another Question by Mapleperson · · Score: 4, Interesting

    Another questions is what happens to the speeding cluster if is was flung out by a bigger galaxy. One would assume the the dark matter that originally present in the cluster would not take the same track. Without the supporting dark matter the radial velocities are too great for the outer stars of the cluster to continue orbiting the system. One would think that there should be trail of stars left behind. Could be a great way to investigate dark matter interaction with galaxies.

  10. Towards Us by Infiniti2000 · · Score: 5, Informative

    The Virgo Cluster galaxy, M87, has ejected an entire star cluster, throwing it toward us at more than two million miles per hour.

    I can imagine people getting alarmed at this, but they shouldn't. If it's truly directly towards us (unlikely), and never veers off course (unlikely), it would still take about 18.3 million years to reach us.

  11. They know something by utoddl · · Score: 2

    Sounds like M87's Puppeteers know something and are heading for higher ground.

  12. Hard to imagine cluster holding together... by Thagg · · Score: 3, Interesting

    For a three-body slingshot to work, the object would have to get pretty close to one or both of the black holes -- considerably closer than the size of a globular cluster. At that distance, the tidal forces around the black holes would rip the cluster apart. I just can't see this happening.

    I suppose it's time to do some simulations :)

    --
    I love Mondays. On a Monday, anything is possible.
  13. Re:12 Parsecs by stjobe · · Score: 4, Informative

    Whoosh.

    That was the sound of the Millenium Falcon - the only ship to ever do the Kessel Run in under 12 Parsecs - passing over your head.

    --
    "Total destruction the only solution" - Bob Marley
  14. In other words by Tablizer · · Score: 2

    it got cluster fscked

    --
    Table-ized A.I.
  15. The Cluster replies, by PPH · · Score: 3, Funny

    "I've been thrown out of classier places than this!"

    --
    Have gnu, will travel.