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Supernovae, the Fate of our Sun, and the Distribution of Heavy Elements in the Earth

-- Carl Judd | March 31, 2021

Question:

“So is it safe to assume all the star’s potential fuel was burned in very short time (during a supernova) instead of millions of years?

Also, can you answer two more questions please- when a star like our sun collapses in on itself as a red giant and disperses its outer shell/becomes a white dwarf, is there no nova (burst of light) and forced quick fusion of the remaining mass like in a larger mass star? I would think there has to be some for a sort of mini-nova.

Finally, I understand all the heavier elements come from star death, but does anyone know how they get dispersed so perfectly throughout the Earth? I think when the Earth is forming and so hot every element naturally accumulates in certain places based on their structure. Kind of like when everything settles in different places in water based on their makeup.”

-- Carl Judd

Answer:

To answer your first question, I believe that the answer is yes, in that almost all of the nuclear fuel available for fusion reactions in a star gets suddenly used in the fusion reactions which take place in the supernova explosion. For a specific example calculation for a Type Ia supernova, which results from a white dwarf star being driven over its critical mass limit, see the nice Physics Stack Exchange answer to this particular example.

Regarding your second question about the fate of our Sun, our current understanding of the evolution of stars like our Sun is that it will not produce a nova. Nova events are associated with stars more massive than our Sun.

As for your third question about the distribution of heavy elements in the Earth, I believe that a very detailed answer to this question has been provided on the Physics Stack Exchange. There is some condensation of elements in specific areas on the Earth (which is where we often build mines to extract those elements), but in general the formation process, and subsequent geological processes, tend to distribute elements somewhat uniformly throughout the Earth.

-- Jeff Mangum

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