We are made of star dust - how?

IamtheWalrus

I'm well versed in the creation of heavy elements in the fiery furnaces of stars and we are made of those elements but I don't understand how. We started as a fertilised egg and the cells make copies of themselves. But where does star dust come in to it?

IrishKnight

More or less all elements were formed in the cores of stars. When these stars die, they explode the contents outwards into space. This star dust would then go on to make other stars, form planets and so on and so forth. So when it is said we are made of star dust, we are talking about the elements that make up your every cell...

EDIT:I should point out that no new matter can be made, there is a set about of "stuff" in the universe and all this stuff came from the big bang, but the elements were made within the stars. But the stuff can change form, like ice to water to steam.

JRant

Cells are formed by complex protein structures, which are in turn a result of non-covalent interactions between amino-acids. These amino-acids are made up of the heavier elements found in the periodic table and can only have been formed in the heart of a collapsing star. Hence, we are all made of star-dust

IamtheWalrus

I get all that but how does the element actually get into the cell? Like you have a baby in the womb, growing. There is more material in a 1 month old baby than a 9 month old one. Where does this material come from? Is it that the material is from its mother?

IrishKnight

IamtheWalrus wrote: »

I get all that but how does the element actually get into the cell? Like you have a baby in the womb, growing. There is more material in a 1 month old baby than a 9 month old one. Where does this material come from? Is it that the material is from its mother?

From the food the mother eats, the air that fills her lungs etc. All the elements in the universe get recycled over and over again. Human eats, human craps, crap feeds plants, plants get cooked, human eats and so on

Your question reminded me of an old thread, which asked How do atoms build us? The very last post by kiffer is rather good and you may want to give it a read...

IamtheWalrus

IrishKnight wrote: »

From the food the mother eats, the air that fills her lungs etc. All the elements in the universe get recycled over and over again. Human eats, human craps, crap feeds plants, plants get cooked, human eats and so on

Your question reminded me of an old thread, which asked How do atoms build us? The very last post by kiffer is rather good and you may want to give it a read...

Thanks. Maybe that thread is what I need.

Capt'n Midnight

This graph explains it all including Nuclear Fusion and Nuclear Fission.

Fe56 is one of the elements with the highest binding energy. This means it's most stable.

( For me it helps to imagine this diagram being upside down with Fe at the bottom - it's got the least energy to release - and the others above it. )

In a fusion nuclear reaction you are generally moving to the right while the curve still goes up. When you fuse two lighter elements together to form a heavier one the difference in energy is what is released. Same when you split uranium in two except you are moving to the left, and again while the curve goes up.


There are various nuclear cycles in a star - and in general you are moving to Ion unless it's a supernova where there is so much energy that heavier elements are formed even though they have lower binding energy. That's like when you drop a brick into water and some of the splash is higher than where you dropped the brick from.

https://en.wikipedia.org/wiki/Stellar_nucleosynthesis

The most important reactions in stellar nucleosynthesis:

Hydrogen fusing:
Deuterium burning
The proton-proton chain
The carbon-nitrogen-oxygen cycle
Helium burning:
The triple-alpha process
The alpha process
Burning of heavier elements:
Lithium burning: a process found most commonly in brown dwarfs
Carbon burning process
Neon burning process
Oxygen burning process
Silicon burning process
Production of elements heavier than iron:
Neutron capture:
The R-process
The S-process
Proton capture:
The Rp-process
Photo-disintegration:
The P-process

https://en.wikipedia.org/wiki/Triple-alpha_process
https://en.wikipedia.org/wiki/CNO_cycle