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Fast-Moving Black Hole

Posted by michael on from the vacuum-cleaner dept.

otisaardvark writes "New Scientist story about a very fast moving Black Hole in our very own Galaxy. Seems it was formed from a supernova explosion. I wish stars like this could have a more exciting name than GRO J1655-40 though. More at the BBC."

4 of 49 comments (clear)

  1. Re:What should I believe? by NineBall · · Score: 3, Insightful

    Remember, in science, no theory is ever actually correct, merely proven to be beyond reasonable doubt.

    --
    You may not agree with what I'm saying but I'll kill you for my right to say it
  2. Re:I wonder... by Santos+L.+Halper · · Score: 2, Insightful

    Of course it is just gravity. The important thing is that it has *a lot* of gravity. Drop your weight from 1000 feet over a black hole (if you could get that close) and you'll get a lot more energy than if you dropped the same weight off a 1000 foot cliff here on Earth.

    --

    "Ask not for whom the bone bones. It bones for thee." --Bender
  3. This doesn't make sense to me. by Peter+T+Ermit · · Score: 4, Insightful
    Can anyone help me understand? Two problems:

    1) The black hole has a companion star, so wouldn't a kick of that magnitude tear it away from its companion and preclude it from acquiring another until it slows?

    2) Even ignoring the mass of the companion, the estimates are that the BH is about 7 solar masses. That means that the BH has acquired a kinetic energy of 1/2 * 7 * (2^30 kg) * (10^5 m/s)^2 = about 10^41 J of energy, which is about 1/1000 of the energy of the SN explosion (10^51 erg = 10^44 J). To me, that seems like an exceedingly large fraction of a roughly isotropic explosion converted into motion. It gets even worse if you throw in the mass of the companion.

    Anyone have any insights into how this can happen?

    1. Re:This doesn't make sense to me. by Peter+T+Ermit · · Score: 4, Insightful
      10^54 ergs would resolve a lot of the difficulty, but I thought that SNs couldn't produce anything much more than 10^51 or so ergs; anything significantly greater than that is a "hypernova" and is thought to have a different origin. (Or that the SN is beamed, which gives the illusion of higher energies.)

      Even so, I'm still confused about the companion, as the system's binding energy is probably rather less than its kinetic energy.