The origins of gold...
19 Jul 2013 6:32:09 UTC
Topic 197075
(moderation:
I found an interesting Article about a neutron star collision. It produced gold that has 10 times the mass of the moon!
Apparently gold can only be produced at such high energetic events. It's quite cool to know that many of us carry the result of neutron star collisions on their fingers ;)
Btw: For the german speaking user an article in german can also be found here. However, it does not feature as much information as the original one.
The origins of gold...
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I was under the impression that elements heavier than iron was created in super novas.
Whatever the truth is .. I'd rather wear a piece of supernova than collision debris :)
Edit: Hmm .. maybe colliding neutron stars are also classified as supernovas?
Or planets made of mass of
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Or planets made of mass of diamonds and lead.
55 Cancri e
http://www.space.com/18011-super-earth-planet-diamond-world.html
http://en.wikipedia.org/wiki/55_Cancri_e
http://www.space.com/159-strangest-alien-planets.html
Not that we will ever get closer than a space telescope.
RE: I found an interesting
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Wow ... I had always (wrongly) thought only tiny amount of matter could escape a neutron star.
One of my favourite nasa pages.
The amount of energy needed to propel large amounts of matter to escape velocity must be enormous.
How do these events compare to our run of the mill supernova... (in terms of creating useful matter) ?
How does the matter then clump back together after these events?
The numbers are boggling.
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The numbers are boggling. Neutron stars are nearly black holes so the mass/energy densities are enormous.
Iron nuclei* are at the bottom of the binding energy valley ie. maximum stability as there are no more stable nuclei ( in the sense that it takes the most energy of all nuclei to separate all the protons and neutrons to infinite separation ). That's why if you fuse upwards in atomic number from Hydrogen within a star then you eventually reach a point where further fusion requires energy input - to go to higher atomic numbers from Iron. Now if you start from say Uranium then fission ( going to lower atomic numbers ) releases energy and so one can cascade downwards. But this is simplistic as the 'valley' has 'ledges' and 'notches' so that local minima occur. Hence some nuclei need a nudge to get them out of those. Lead is a good example, while it is the end product under most conditions of fission it is still higher up the valley side than Iron.
What's happened with these neutron stars is that kinetic energy of the collision has provided the energy to fuse above Iron. This also happens in supernovae in that the infalling matter during core collapse does much the same.
Note that binding energy is quoted in units of Mev per nucleon - quite high in the general sense of say typical thermal kinetic energies. Also Iron 56 is an even-even nucleus ( multiple of four nucleons - two protons and two neutrons ie. alpha particle ) and there is special stability in that.
*There's a 'nearby' Nickel nucleus which is slightly more tightly bound but : for other reasons either doesn't form, or if it does then under typical conditions of production, decays.
Cheers, Mike.
I have made this letter longer than usual because I lack the time to make it shorter ...
... and my other CPU is a Ryzen 5950X :-) Blaise Pascal