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Space Science

Fast-Moving Black Hole 49

Posted by michael 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."
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Fast-Moving Black Hole More

Fast-Moving Black Hole

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  • Here is more cool black hole news: (Score:4, Interesting)

    by Neil Blender ( 555885 ) <neilblender@gmail.com> on Tuesday November 19, 2002 @03:37PM (#4709765)
    Merging Black Holes [thestar.com]
  • If we ever get close enough to one... does a Black Hole have any practical use? Or are they like potholes in the road? Great movie though - any sign of a DVD?

    • Re:I wonder... (Score:5, Funny)

      by GigsVT ( 208848 ) on Tuesday November 19, 2002 @03:48PM (#4709852) Journal
      Yep, if we ever got close enough to a black hole, it would be the solution to global warming, corruption in government, freedom on the Internet, minority rights, energy production, and pretty much every other petty human problem you can think of.

    • Re:I wonder... (Score:2, Interesting)

      by Cs.Ender ( 615148 )
      I can think of a couple ways to use a black hole to generate power. Rotating black holes have huge amounts of kinetic energy, and such a hole that had an electric charge could be used as a huge generator, if we could get an electric field large enough to surround it.

      The other method uses very small holes, about the size of a proton with the mass of a mountain. Due to Hawking radiation [ucr.edu], such a hole would put out more power than a six nuclear power plants (if I remember the statistic).
    • I've read that if you could get close enough to a black hole, and you threw something into it that was attached to a cord strong enough, the black hole will pull the matter into in, thereby pulling the cord, which in turn can be hooked to a turbine to produce electricity. The book (The Last Three Minutes) says that theoretically, you could get energy consistant with e=mc^2 this way.
      • This is just gravity. If you took a bit of rope with a wieght on it to the top of a bridge, and threw it down, you could use the moving rope to generate electricity.

        • 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.

    • Time Travel (Score:3, Interesting)

      by Merlin42 ( 148225 )
      Im not so sure that this is really practical in the sense you meant, but just being near a large enough blackhole would provide a simple one way time machine (cf twins paradox).
    • If a large (star-like mass) black hole ever gets close enough to the solar system for us to seriously contemplate doing cool things with it, then the solar system will be destroyed without any wormhole, time-travel, super-electricity-generation or other cool things happening. Further, no technology we can plausably forecast could possibly let any humans survive the event.

      Executive summary: we ain't near old enough to play with this kinda toy.
    • Did you ever see that one Pinky and the Brain? They created miniature Black Holes in a jar and sold them as garbage disposals, i don't remember how this tied into their plot to take over the world, bum bum bum... [insert theme song]

  • This doesn't make sense to me. (Score:4, Insightful)

    by Peter T Ermit ( 577444 ) on Tuesday November 19, 2002 @05:35PM (#4710766)
    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?

    • Re:This doesn't make sense to me. (Score:1, Informative)

      by Anonymous Coward
      Supernova lose about 10% of the mass of the final neutron_star/BH. In this case, final mass is 7 solar mass, so the energy released is 0.7 * solar_mass * c^2 which is about 10^54 ergs.

      • Re:This doesn't make sense to me. (Score:4, Insightful)

        by Peter T Ermit ( 577444 ) on Tuesday November 19, 2002 @07:07PM (#4711436)
        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.

    • Nice to see that this bothers people who have detailed understanding of the physics.

      Seems there are several problems unresolved questions here.

      Is the black hole moving with a campanion star? Or, just skimming off some mass as it passes by? If it is actually moving *with* the companion star, what kept them together? Assuming a SN explosion accelerated the black hole to 400,00 kph, how did it drag along another star? Even if they were a close binary pair before the SN explosion, wouldn't the black hole now have system escape velocity?

      Another question, how off balance does the explosion have to be to generate this kind of speed? If the explosion is 1% of balance, how much mass energy was released in the total explosion to get this speed? How do you get a SN explosion that is that off balance?

      Could this pair have been accelerated by another mechanism such as a close pass to a tight binary star system? How tight would it have to be? What kind of stars (neutron, black holes...) to get a pair with enough energy to speed something up like that?

      Like you said. this doesn't make sense.

      Stonewolf

  • We need to launch the Cygnus [imdb.com] immediately! Paging Dr. Reinhardt...

  • J1655 (Score:2)

    by suss ( 158993 )
    I wish stars like this could have a more exciting name than GRO J1655-40 though.

    Yeah, J1655 is such a jerky middle name!
    • more exciting name than GRO J1655-40

      How about the Oh Shit Everything's Getting Sucked Into It and We're All Gonna Die Star of Death?

  • Black Hole fastly moves you. And just about everything else in the vicinity...

  • Crap. (Score:2)

    by grub ( 11606 )

    I've always liked the slow black holes. They come meandering towards you like a sloth and are easy to sidestep around.

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