http://news.bbc.co.uk/2/hi/science/nature/3083875.stm

Was I the only one not exactly bowled over by this? Yeah, if you go back far enough, the elements to create planets didn't exist yet.

Or is it just a case of "Oh, boy! An actual observation matched theory!"?

this is kind of neat! it almost implies that the first stars were only composed of light elements. (ok, so that is stated outright. the rest is somewhat implied). someone correct me on this, but wht it sounds like is that these stars took the hydrogen, helium etc and fused (fissioned? what's the right word here?) into heavier elements. lithium, carbon, oxygen, neon, etc. a generation or two of stars building on the previous would have taken the former's expelled elements and used them create still heavier iron, copper, zinc...

if this is true, and each generation creates a series of heavier elements (perhaps one row on the periodic table? it's an easy reference if nothing else. :-? ) then could there be elements in existence that we are unaware of? from stars that may be a generation or two ahead of our sun? essentially saying that stars are not only nuclear reactors, but elemental factories?

how cool would that be?

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None to speak of

Plausable in theory but unlikely. I don't have the info handy but elements above #103 (?) have so far found to be very unstable and last fractions of a second. Most (all?) of the elements above uranium are radioactive and would decay. Stellar spectroscopy would be able to tell if stars contained any of these heavier elements so if anyone has references to such 'very heavy' stars please share.

yeah...that was my thought too. figured it wouldn't hurt to ask though! and yeah, if anyone knows more...

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None to speak of

As far as I remember, none of the elements above Uranium are considered 'naturally occurring'. Nor is Technetium. I also seem to recall that fusion reactions in stars don't create elements heavier than iron, but I wouldn't be able to explain why not, nor where the other elements come from. But hopefully someone else on this board can either correct me or explain why. :-?

Bismuth, element 83 (one higher than lead) is the heaviest element with at least one stable isotope. Some of the heavier elements such as uranium (92U238 - 4.7 billion years) and thorium (90Th232 - 1.4 trillion years) are so long lived that they are almost stable.

Fusion is an exothermic reaction for elements up to iron (Fe56). For iron and above, fusion is endothermic. Therefore, all elements above iron are only formed in supernovae.

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Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson

Well, if I remember correctly...

Fusion of elements to form elements up to iron gives out more energy than it requires to initiate. As I recall, the initial fusion reactions in a star start up when the collapse of the gas cloud causes hydrogen to fuse. This begins the reaction which maintains the balance between the star's collapse under its own gravity and the expansion due to the release of energy from nuclear fusion. Once iron is made, fusion requires more energy than it releases, so the star is no longer able to generate the energy needed to prevent itself collapsing under its own weight. The collapse now provides the energy for the fusion of iron to form heavier elements, but this process does not produce the energy to stop the collapse, so the outer layers of the star go speeding towards the core and rebound, producing the supernova which scatters the elements produced in the star across the universe.

I'm sure someone better versed in astronomy than me (i.e. most of this community I expect!) will correct any mistakes I made, but that's my understanding of the process.

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"The very powerful and the very stupid have one thing in common: They don't alter their views to fit the facts, they alter the facts to fit their views." The Doctor, Doctor Who: The Face of Evil.

Wouldn't this theory be wrong if its determined that gas giants are formed from knots of material in the dust disk, as opposed to having a massive rock core? Even those early monsters must have had accretion disks.

I've read that Technetium isn't naturally ocurring on earth... they're found traces of it being craeted in stars.

It isn't found naturally, except in stars, because it does not have any stable isotopes. Its radioactive isotopes all have short half-lives so any formed in a star would eventually vanish. Fusion reactions in a star would produce small amounts of it.

Francium is another element that is not found on Earth due to not having any stable or long lived isotopes. Isaac Asimov once estimated that at any given time, there are less than 100 atoms of it in the Earth's crust!

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Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson