Heavy elements in stars

[julian_c]

Hi,<br /><br />Am I right in thinking that there will be higher levels of heavy elements in the outer layers of younger stars than older stars? <br /><br />Am I also right in thinking that the composition of the outer layers of stars is down to the fact that older stars were formed primarily from helium and hydrogen and therefore their outer layers contain little or no heavy elements. However, because of steller processing of heavier elements, younger stars are formed from material containing higher levels of heavy metals?<br /><br />Are there any other less important processes that affect the composition of the outer layers of stars?<br /><br />Many thanks in advance!<br /><br />Juilan

 

[wick07]

It depends on what you mean by "heavy elements". The fusion process in stars can only produce up to iron. After that there is no more energy to be had in fusion. It is my understanding the elements heavier that iron are made via supernovae.<br /><br />Older stars should have very little, if any elements larger than iron, since they were formed prior to other stars going supernova. Younger stars would be more likely have these elements present.<br /><br />As for where in the stars these elements can be found I would expect to find the heavier elements in the middle, since they will tend to "sink". But I could be wrong about that. <div class="Discussion_UserSignature"> <p><font color="#3366ff"><strong>_______________________________<em> </em></strong></font></p><p><font color="#0000ff"><em>"</em>If you are surrounded by those who constatly agree with you, then you're in an intellectual vacuum.  If you feel like trying to make a difference, you have to BE different.  How can you do that without interacting with those who are different from yourself?"</font></p><p><font color="#0000ff">-  a_lost_packet_</font></p> </div>

 

[mindmute]

agreed, the heavier elements should be close to the core.<br /><br />however, it is my understanding that iron is the heaviest element that can fuse in a star of 1 solar mass.<br />heavier elements can be fused in stars of greater mass.<br /><br />yes, young stars of any mass can have heavy elements absorbed during their creation. anyone care to postulate what 10th generation stars may be composed of?

 

[Saiph]

Julian: You are correct.<br /><br />There are some odd stars out there that may have some wierd mixing mechanisms, called "Helium Stars" they have an absurdly high helium content which may indicate the core mixing with the envelope.<br /><br />After star formation, and before star death, I can't think of anything that really affects the envelope and surface composition in any significant fashion. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>