Using Supercomputers To Predict Signs of Black Holes Swallowing Stars

aarondubrow (1866212) writes "A 'tidal disruption' occurs when a star orbits too close to a black hole and gets sucked in. The phenomenon is accompanied by a bright flare with a unique signature that changes over time. Researchers at the Georgia Institute of Technology are using Stampede and other NSF-supported supercomputers to simulate tidal disruptions in order to better understand the dynamics of the process. Doing so helps astronomers find many more possible candidates of tidal disruptions in sky surveys and will reveal details of how stars and black holes interact."

Comments

Re:Impossible

[Suki I]

How can a black hole swallow a star if the star's clock slows to a stop as it approaches the event horizon?

Just be thankful that this breakthrough is coming just in the nick of time dilation.

Re:Impossible

[wonkey_monkey]

How can a black hole swallow a star if the star's clock slows to a stop as it approaches the event horizon?

Because it doesn't.

The star's clock may slow to a stop relative to ours, sitting safely outside, but as far as the star is concerned, its clock continues to tick happily away. If the black hole is big enough, the star wouldn't be in the least perturbed by the experience.

Ah! Now it makes sense.

[140Mandak262Jamuna]

There was a electromagnetic simulation software called Ansoft-HFSS. Most structures it dealt with were IC chips, packages, PCBs and antennae. Most of these were drawn in microns, or mils (milli inches, don't ask), mm or at the most in meters. But the drop down box for unit selection went all the way to light years. I thought must be some inside joke, some user must have complained some unit was not available and the developer, in a fit of indignation, must have added every damned length units he/she could find. Now it makes sense. You can use that software to simulate black holes gobbling up stars.

Re:Impossible

[wonkey_monkey]

I think you might have that the wrong way around. From the star's perspective - if the black hole is big enough - nothing untoward occurs. It certainly won't see its own clock slowing down. From an outside perspective, objects approaching an event horizon undergo time dilation and fade from view, but are never seen to cross the horizon.

Re:Impossible

[Neil Boekend]

Correct me if I am wrong, but my limited knowledge of what happens tells me this:
Probably, assuming the observer is infinitely strong and can survive the gravity shear and immense pressure of the black hole:
From the observers POV the universe speeds up, until the surroundings (except for the black hole itself) become a bright light, because time dilation causes the cosmic background radiation to appear like visible light.
Then the black hole evaporates due to Hawking radiation and the observer is free again. When checking an outside ("absolute") clock billions of years have passed but the observer only felt a relative short while. The observer never encountered anything that could be considered a black hole. Time dilation reached near infinite before it could get there. The observer did encounter a lot of mass, mass that was falling into the black hole, never reaching it because time dilation didn't allow it to reach anything.
This mass has unknown properties. It is far denser than neutronium. It is still falling towards the core, only slowed down by time dilation.
The star itself was torn apart way before the "visible cosmic background" part. It kept falling towards the black hole as part of that mass with unknown properties.

From the outside an object doesn't exactly fall into the event horizon. It falls towards it but slows down before it. The light reflected or emitted by the object gets redshifted to nothingness. The event horizon does grow to meet the object.
Assuming the event horizon doesn't grow extremely fast the object will be invisible due to extreme redshift. Whether it is torn apart by gravity shear before that depends on the mass of the black hole and the strength of the object.