Thread: Do Dying Stars Really Give Birth To Other Stuff?

We hear it all the time, it seems a cliche' now. Dying stars give birth to other things, nothing dies it merely changes, but is this all philosophical mumbo jumbo? Does it mean anything?

Stars shine by fusing light elements like Hydrogen and Helium into heavier elements like, say, carbon, Oxygen, Argon... for heavier stars, Iron... etc - effectivley they are turning Hydrogen into other stuff through nuclear fission. E=MC^2 and all that.

Of course when a star is doing this during it's life, all that other stuff stays inside the star's core area where it was formed. It is not until the star is unable to hold itself together due to a higher energy fission taking place under increased pressure that those new materials - literal billions of years in the making - are able to be released into the space around the star.

While a star forming Nebula would be mostly Hydrogen, a planetary (star death) nebula contains many more different elements. Small stars much less variety of elements (and not as many heavy elements) compared to large stars.

Stars literally are turning Hydrogen into other things in the act of forming light and heat.

When a star dies by going supernova and expelling it's gasses into the surrounds as the fusion process runs away due to the cessation of the flow of hydrogen in the core and the lack of easy fusion due to that, it throws all the byproducts of Fusion (Helium, Oxygen, Argon, Carbon, Iron, etc etc) out into the space around it.

If there were no stars in the Universe, the universe would consist of basically only Hydrogen gas.

of course if the universe only consisted of Hydrogen gas, the natural action due to gravity would be the formation of stars.

I take it your answer is YES?

yes

+ it's not philosophical mumbo jumbo if you receive the nobel prize for it

I'm not sure if this is correct or not, but i do remember reading somewhere that carbon can only be created at certain temperatures. The big bang (apparently) would have been too hot and it has never been warm enough on earth to create it, the one place it would have been just right would have been a supernova, so in theory, dieing stars gave birth to our planet and all living things here including us, seeing as much of our body is made of carbon.

All this would need to be confirmed by one of the more knowledgeable members of the forum though.

Musicalaviator summed it up. Heavier elements are created when they are fused in a star. Of course, when elements like iron are fused... well, the energy is enormous; so big it essential blows the star up, AKA a supernova.

The sun is a third generation star. Only third generation stars have sufficient metals (in astrophysical terms, these are any elements heavier thn helium) to allow formation of planetary systems and potential biosphers.
So the answer to the poll question is a resounding yes.

so what are 2nd generation stars - enriched with metals, but not to the extent that a planetary sytems forms ?

This reply is off the top of my head since I have neither the time nor the inclination to check it out in detail.

At an early stage in observational spectroscopy it was noted that stars fell into two groupings. Population I stars, similar to the sun with high levels of metallicity, and Population II stars composed almost exclusively of hydrogen and helium. The Population II stars seemed to dominate the globular clusters that surround the galaxy and those portions of the galaxy away from the spiral arms. Population I stars were most common in the spiral arms.

As our understanding of stellar evolution improved we realised that the Population II stars were the older group.

More recently, our investigations of the early Universe have led to the recognition of what are called Population 0 stars. These were the first stars that formed not long after the Big Bang. They were composed entirely of hydrogen and helium. (OK, there might have been a tad lithium, or beryllium. ). These contained many giant, and therefore short lived stars, that went supernova, and produced the material for the formation of the second generation, Population II stars.

The metallicity of these second generation stars was low. The consensus appears to be that it was too low to provide enough material for the formation of planets. (Personally, I suspect there may have been enough in isolated instances, but as an overall tendency it is probably valid.)

Hope that wasn't too long winded.

Ophoiolite, good reply. Hope you don't mind my repeating what you said, but I think it can't be repeated too often.

The early universe was composed mainly of hydrogen gas as you say. The earliest stars formed from these gasses. Hydrogen is the fuel for nuclear fusion in stars, and nuclear fusion is the process which is responsible for the creation of new elements...stellar nucleosynthesis. All the chemical elements heavier than hydrogen were created by this process inside stars. These stellar-created chemical elements are then spread throughout the galaxy as these early stars exploded. These elements then are included in the process of the creation of new stars and their proto-planetary systems which result in heavy element rich planets like the earth.

Every atom in your body besides hydrogen or helium were created by nuclear fusion inside stars that existed before our solar system was born. So every atom you're made of was created by and once existed inside a star. Every atom of everything you look at each day was created in this way, or was created by chemical processes based on these stellar-created elements.

as the laws of the conservation of matter states: Matter can neither be created or destroyed only changed. New stars and formed out of the remains of dead ones whoich is why we have such elemants such as Uranium etc.