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Star Cluster Ejected From Galaxy At 2,000,000 MPH 133

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

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  • by bjorniac ( 836863 ) on Friday May 02, 2014 @10:26AM (#46898951)

    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.

  • Towards Us (Score:5, Informative)

    by Infiniti2000 ( 1720222 ) on Friday May 02, 2014 @10:29AM (#46898977)

    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.

  • by CreatureComfort ( 741652 ) on Friday May 02, 2014 @10:39AM (#46899071)
    Nah, at a constant 1 G acceleration you could get to 2 M mph in under 51 hours.
  • Re:12 Parsecs (Score:5, Informative)

    by stjobe ( 78285 ) on Friday May 02, 2014 @11:30AM (#46899611) Homepage


    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.

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