Where do the heavier elements come from, such as those found in planets?

In summary, the sun is primarily composed of hydrogen and helium, with a small percentage of heavier elements. The planets in our solar system have different compositions due to the process of planet formation, which does not allow for terrestrial planets to have the same composition as the sun. Heavier elements are produced in supernovae, but there are still details that need to be filled in. The objects in the asteroid belt are composed of similar materials to the planets, but have been subjected to different processes.
  • #1
Kaldanis
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Something similar to this came up in a lecture but it wasn't explained very well. From wikipedia it seems that our sun is made up of 74.9% Hydrogen and 23.8% Helium. The final 1.3% is made up of heavier elements such as oxygen, carbon, neon, and iron.

If the the entire solar system condensed out of the same cloud of matter, how come the planets are composed of such different materials to the sun? Where do the other elements come from?

I heard that heavier elements were thought to be made in supernovae, but then also heard that that was just a theory made to hide the fact that no one really knows. Does this mean that there would have been a previous star in this general area in space we occupy that went supernova, then our current solar system was created out of the remains?
 
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  • #2
Kaldanis said:
Does this mean that there would have been a previous star in this general area in space we occupy that went supernova, then our current solar system was created out of the remains?

Pretty much, yes. Sol is a recent Population I star. The heavier elements were fused in the supernovae of more ancient Population II stars. (larger number = earlier star)

http://en.wikipedia.org/wiki/Star_population
 
  • #3
Kaldanis said:
If the the entire solar system condensed out of the same cloud of matter, how come the planets are composed of such different materials to the sun? Where do the other elements come from?
Good question. The answer is in planet formation---you couldn't make planets the size of Earth ('terrestrial planets') with the same composition as the sun, because they wouldn't stay bound together. The 'gas-giants' are basically the smallest objects you can form in this environment that are gas dominated, but they still require a more dense core to have formed.

Kaldanis said:
I heard that heavier elements were thought to be made in supernovae, but then also heard that that was just a theory made to hide the fact that no one really knows.
Heavier elements are definitely produced in supernovae, and the numbers do work out quite well. That isn't to say that all of the details are worked out, for example, the exact contribution of different types of supernovae aren't perfectly worked out... This isn't my field of expertise, but I'm sure there are lots of details that need to be filled in.
 
  • #4
The sun has plenty of heavy elements, but, captured the majority of the hydrogen and helium available in the primordial solar system. This gives it a higher fraction of these elements - especially compared to the terrestrial planets.
 
  • #5
Thank you. So should all the objects in the asteroid belts be composed of similar materials to the planets?
 
  • #6
Kaldanis said:
Thank you. So should all the objects in the asteroid belts be composed of similar materials to the planets?
Welllll, similar, yes. They came from the same gas and dust that formed the solar system, but have been subjected to different processes.

eg. the inner planets are all rocky, the outer planets are (mostly) gaseous due to these different processes too.

But yes, the asteroids are thought to be a planetoid that might never have formed due to Jupiter's interference.
 

1. Where do the heavier elements come from?

The heavier elements, such as those found in planets, are formed through a process called nucleosynthesis. This involves the fusion of lighter elements in the cores of stars, as well as in supernova explosions. These elements are then dispersed into space and can eventually form into new stars and planets.

2. How are heavier elements formed in stars?

In stars, the fusion of lighter elements into heavier ones occurs through a series of nuclear reactions. These reactions require extremely high temperatures and pressures, which can only be achieved in the cores of stars. As the star ages and runs out of lighter elements to fuse, it begins to fuse heavier elements until it eventually reaches iron, which cannot be fused any further.

3. What happens to heavier elements when a star explodes in a supernova?

When a star explodes in a supernova, it releases a tremendous amount of energy and pressure, causing the fusion of elements to occur at an even faster rate. This leads to the creation of even heavier elements, such as gold and silver. These elements are then dispersed into space, where they can eventually form into new stars and planets.

4. Are all elements in the periodic table formed in stars?

No, not all elements in the periodic table are formed in stars. Elements like hydrogen and helium, the most abundant elements in the universe, were formed during the Big Bang. Heavier elements, such as those found in planets, are formed through the fusion of lighter elements in stars and supernovas.

5. Can heavier elements be formed in other ways besides fusion in stars?

Yes, heavier elements can also be formed through cosmic ray spallation, which is the process of high-energy particles colliding with atoms and breaking them apart to form new elements. This occurs naturally in space, and can also be artificially induced in particle accelerators on Earth. However, the majority of heavier elements in the universe are formed through fusion in stars.

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