Creation of elements heavier than Iron

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Creation of elements heavier than Iron

Postby Gryllo » Thu Dec 07, 2017 11:11 am

Does the recent discovery that elements heavier than Iron are created when two neutron stars collide mean that the earlier belief that heavy elements are created in a supernova explosion is wrong, or do both process lead to the creation of elements heavier than iron?

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Re: Creation of elements heavier than Iron

Postby Gfamily2 » Thu Dec 07, 2017 12:43 pm

An excellent question.
It certainly seems to me that the recent observation of a NS/NS collision has made a difference to our understanding, and seems to have introduced a new pathway for creation of heavier elements.

I was recently at a talk that was partially about Black Holes (it was mostly about Gravitational Wave detection), where the speaker suggested that a core collapse supernova of ultra massive stars may be so big that the entire interior of the star is dispersed, with nothing left in the core, so no Pulsar/Neutron Star or Black Hole left behind. In this case, I suppose, the pathway to create heavy elements may well be the same as NS/NS merger - i.e. from a degenerate 'neutron star' material that is created and expelled during the supernova.

It's interesting to compare two "where were elements created" diagrams that have featured on APOD recently.
January 2016
https://apod.nasa.gov/apod/ap160125.html

October 2017
https://apod.nasa.gov/apod/ap171024.html

Spot the difference.
Anyhow, although the latter diagram includes NS/NS merger as a major source, it continues to suggest that at least SOME of the heavy elements are created in SN events.
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Re: Creation of elements heavier than Iron

Postby Gryllo » Thu Dec 07, 2017 1:09 pm

Dear Gfamily2,

thanks for the quick reply and especially to the links to the two periodic tables.

The 2016 version is in line with what I have understood previously, for example from Brian Cox's 'Wonders of the Universe', but the 2017 table puts the origin of the elements into a whole new context.

Best wishes

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Re: Creation of elements heavier than Iron

Postby EIZO » Thu Dec 07, 2017 3:32 pm

I have just been watching "the universe" this afternoon, and it was interesting to see that when a star creates Iron it is then the death of that star literally within seconds
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Re: Creation of elements heavier than Iron

Postby The Man with the Corrugated Iron Roof » Sun Jan 14, 2018 8:59 pm

I suspect that there is a lot more that we don't know than what we do. Mergers between white dwarves and neutron stars could be rather interesting and so could a merger of two white dwarves that creates an object heavier than the Chandresakar limit (about 1.3 to 1.4 solar masses). A white dwarf heavier than this cannot exist and would create a neutron star and supernova.

It is true, though, that nuclear reactions in regular stellar cores cannot create any elements heavier than iron, unless there's something we haven't discovered yet.
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