Star Crust 10 Billion Times Stronger Than Steel

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drwayne

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ScienceDaily (May 6, 2009) — Research by a theoretical physicist at Indiana University shows that the crusts of neutron stars are 10 billion times stronger than steel or any other of the earth's strongest metal alloys.

Charles Horowitz, a professor in the IU College of Arts and Sciences' Department of Physics, came to the conclusion after large-scale molecular dynamics computer simulations were conducted at Indiana University and Los Alamos National Laboratory in New Mexico.

Exhibiting extreme gravity while rotating as fast as 700 times per second, neutron stars are massive stars that collapsed once their cores ceased nuclear fusion and energy production. The only things more dense are black holes, as a teaspoonful of neutron star matter would weigh about 100 million tons.

Scientists want to understand the structure of neutron stars, in part, because surface irregularities, or mountains, in the crust could radiate gravitational waves and in turn may create ripples in space-time. Understanding how high a mountain might become before collapsing from the neutron star's gravity, or estimating the crust's breaking strain, also has implications for better understanding star quakes or magnetar giant flares.

"We modeled a small region of the neutron star crust by following the individual motions of up to 12 million particles," Horowitz said of the work conducted through IU's Nuclear Theory Center in the Office of the Vice Provost for Research. "We then calculated how the crust deforms and eventually breaks under the extreme weight of a neutron star mountain."

Rest of the story:

http://www.sciencedaily.com/releases/20 ... 110202.htm
 
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Saiph

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Very interesting, not surprising, but interesting all the same. I wonder how cohesive the stuff is without gravity holding it together, as its just a bunch of neutrons you don't have electrostatic forces holding it together...the strong force is whats in play right?


Are they bound well enough to avoid being "free neutrons" with a ~20 min half life?
 
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origin

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Saiph":m54dt8x9 said:
Are they bound well enough to avoid being "free neutrons" with a ~20 min half life?

Interesting quesiton. 20 minutes ain't very long, and having a bazillion neutrons beta decay would not be a very healthy situation to be exposed to!
 
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silylene

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Seems like Larry Niven got it right, when he described the incredibly strength of General Products hulls.
 
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Saiph

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I have heard mention of people working out the 'radiation pressure' due to neutrons tunneling off the surface of a neutron star. Mainly in respect to the possibility of a neutron star being the core of an otherwise typical star. The idea was dismissed not as impossible, but incredibly rare and of no real value other than a mental exercise.
 
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summoner

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petet":3cpryjru said:
Seems like Larry Niven got it right, when he described the incredibly strength of General Products hulls.


My exact same thought when I was reading the article. Now only to find a way to use it.
 
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origin

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summoner":3gd3x9y2 said:
My exact same thought when I was reading the article. Now only to find a way to use it.

I see a few problems a crucible of the material would weigh as much as the moon. Another problem is the mining ships would have a one way trip only to a nuetron star.
 
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CalliArcale

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I suspect that if you could mine neutron star material your technology would be so advanced that you wouldn't need to. ;)
 
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DrRocket

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drwayne":24jkqug6 said:
ScienceDaily (May 6, 2009) — Research by a theoretical physicist at Indiana University shows that the crusts of neutron stars are 10 billion times stronger than steel or any other of the earth's strongest metal alloys.


Scientists want to understand the structure of neutron stars, in part, because surface irregularities, or mountains, in the crust could radiate gravitational waves and in turn may create ripples in space-time. Understanding how high a mountain might become before collapsing from the neutron star's gravity, or estimating the crust's breaking strain, also has implications for better understanding star quakes or magnetar giant flares.

"We modeled a small region of the neutron star crust by following the individual motions of up to 12 million particles," Horowitz said of the work conducted through IU's Nuclear Theory Center in the Office of the Vice Provost for Research. "We then calculated how the crust deforms and eventually breaks under the extreme weight of a neutron star mountain."

Rest of the story:

http://www.sciencedaily.com/releases/20 ... 110202.htm

It would be nice once to see a story in which there was some small indication that the reporter understood the words that he was writing.

"Squeezed together by gravitational force, the crust can withstand a breaking strain 10 billion times the pressure it would take to snap steel." -- from the magazine article

Here is the pre-print of the real journal article. http://arxiv.org/PS_cache/arxiv/pdf/090 ... 1986v1.pdf

The journal article talks abut a breaking strain of 10% which is fairly high, but certainly not a billion times greater than steel. Moreover, it is a sheer strain, which is a rather unusual quantity for use in a material failure criteria, since shear is dependent on the coordinate system, and in principle strain coordinates strain is always zero. To round out the bizarre report, strain is not expressed in units of pressure, but rather is a pure number (sometimes reported as in/in). Stress is expressed in units of pressure, but no stress was evaluated in the journal article.

The objective of the researchers was to determine the potential for asymmetries in the structure of a neutron star that could result in the radiation of gravity waves. So the shear strength is important in the ability to form "piles". But the reporter's contrast with steel is basically meaningless. Well, why let science louse up a good story.
 
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xXTheOneRavenXx

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Isn't that always the way. Reporters take a guess at what scientists mean without actually speaking to the scientists themselves. But you are right Dr. Rocket, perhaps they should have a reporter that has some background or basic knowledge of the subject to which they are writing about.
 
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derekmcd

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Saiph":xbgdlmjv said:
Very interesting, not surprising, but interesting all the same. I wonder how cohesive the stuff is without gravity holding it together, as its just a bunch of neutrons you don't have electrostatic forces holding it together...the strong force is whats in play right?


Are they bound well enough to avoid being "free neutrons" with a ~20 min half life?


IIRC, the "surface" of a neutron star is mostly iron...


Just as an aside, this has nothing to do with the surface of the sun being iron. Some real physics tells us the surface of a neutron star is iron.
 
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DrRocket

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derekmcd":287x45fq said:
Saiph":287x45fq said:
Very interesting, not surprising, but interesting all the same. I wonder how cohesive the stuff is without gravity holding it together, as its just a bunch of neutrons you don't have electrostatic forces holding it together...the strong force is whats in play right?


Are they bound well enough to avoid being "free neutrons" with a ~20 min half life?


IIRC, the "surface" of a neutron star is mostly iron...


Just as an aside, this has nothing to do with the surface of the sun being iron. Some real physics tells us the surface of a neutron star is iron.

This Wiki article indicates that the crust may be composed of iron nuclei, though there are apparently other possibilities.
http://en.wikipedia.org/wiki/Neutron_star
 
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DrRocket

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DrRocket":2xxtrt12 said:
derekmcd":2xxtrt12 said:
Saiph":2xxtrt12 said:
Very interesting, not surprising, but interesting all the same. I wonder how cohesive the stuff is without gravity holding it together, as its just a bunch of neutrons you don't have electrostatic forces holding it together...the strong force is whats in play right?


Are they bound well enough to avoid being "free neutrons" with a ~20 min half life?


IIRC, the "surface" of a neutron star is mostly iron...


Just as an aside, this has nothing to do with the surface of the sun being iron. Some real physics tells us the surface of a neutron star is iron.

This Wiki article indicates that the crust may be composed of iron nuclei plus other stuff including some electrons, though there are apparently other possibilities.
http://en.wikipedia.org/wiki/Neutron_star
 
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derekmcd

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I have no illusions I can maintain a topical discussion about neutron stars and their structure... no shame here. I recall, Saiph, myself, an others had an interesting discussion about "neutronium" and how it would react in Earth's gravitational environment.
 
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SpeedFreek

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Ahh, the old "teaspoonful of neutronium" thread... fond memories! :mrgreen:
 
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thebigcat

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MeteorWayne":2qyggecd said:
Just a spoonful of neutronium makes everything go down... :)

'Scuse me while I wipe coffee off my monitor and keyboard. :lol:
 
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