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Followup on the star torn apart by a black hole: Hubble picture (discovermagazine.com)
110 points by wglb on April 11, 2011 | hide | past | favorite | 20 comments


Back when I studied astrophysics at uni, I also found that the sheer scale of events like supernovaes, black holes, and other similar things, was just mind-boggling and fascinating. So I can totally relate to the author's excitement!

What happens when stars go "boom" in some way is just insanely huge compared to anything we're familiar with.


I'm fascinated by the way physicists are able to blend experimental data with theory to explain what that little dot probably means.

Makes me think of some guy like Feynman sitting in a room with others thinking up and arguing over accretion discs, tides, and how much solar units of mass _that_ black hole must have.

We've come a long way since Copernicus and still have so very far to go.


[deleted]


> It seems like we would truly be looking back in time.

Anything we look at in space is us looking back in time.


and it’s happening 3.8 billion light years away! I'll go with 3.8x10^9 years, which is consistent with the "one digit precision" 40,000,000,000,000,000,000,000 kilometers number.


This proves once again, and on an immense scale I can't even begin to comprehend, that Mother Nature will always win.


The key part:

As it happens, the disk that formed around the black hole was face-on to us, so one of those beams was essentially aimed directly at us.

Anyone know just how focused these beams are?


IIRC it depends on the black hole. Right now there isn't a precise formula for it.

The breakup of the star would form an accretion disc, the jets would form at the axis of rotation. The formation of the jets are classically mechanical (conservation of angular momentum by various means) and so the focus of the jet depends on the speed of the matter being ejected, the amount of matter being ejected and the mass of the black hole.

Moreover, the matter falling into the black hole is heated to plasma level and so there is very strong magnetic activity. As the accretion disc spins, the magnetic field lines twist along the axis of rotation - the same axis as the ejected matter. This has the upshot of focusing the jets very tightly.

http://en.wikipedia.org/wiki/Black_hole#Accretion_of_matter


I'm not sure about these beams, but at least GRBs from collapsing stars come from a relativistic shock wave with gamma of ~1000, IIRC. Such high gamma gives a very collimated beam of radiation, of order 1/gamma, due to relativistic beaming. So taking 1/1000 radians as a ballpark value, 1mrad is about the divergence of a typical laser. (Laser pointers have slightly higher divergence due to the short cavity, but things like He-Ne lasers are typically 1mrad.)


Somebody on one of the blogs mentioned about 5 degrees, make that 3.6 degrees, which is a hundredth of the full circle or 0.06 rad, and since for such values x is approximately tan(x), it would be about 4 billion times 0.06 or 240 million lightyears narrow at our distance.


Octillions, trillions, billions, and a dot in my screen.


Only visible because the ripped apart star particles created "the light of a trillion suns"!!


I am both amused and slightly fearful that the blog for Discover Magazine would use "embiggen" in lieu of enlarge.


I don't see why, its a perfectly cromulent word.

[ http://en.wikipedia.org/wiki/Cromulent#Embiggen_and_cromulen... ]


This certainly can't bode well for the planets that sun supported.


A GRB plays an important part in the novel Diaspora by Greg Egan. I'd recommend it if you're interested in learning what would actually happen were we to be closer. (Without being a trained astrophysicist, the events in the novel seemed plausible, so I assume Mr. Egan did his homework).


Just read this book. One of the most mind-melting things I've ever read. Every other page introduces a new concept even more staggering than the last. It deserves its own thread here to be honest.

It's about a posthuman society's reaction to a GRB in their vicinity, and its basically one long thought experiment about the various consequences of the human race abandoning corporeal existence.


These planets were torn apart long time ago - when that black hole was formed. Before forming that black hole stars were exploding, so all ~nearby planets were most likely blown away.


Even if there somehow were planets orbiting the star, they would have been sucked in as soon as they got the black hole side of their orbit.


My god - it's full of... star


Mayan prophecie, anyone?




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