Heavy elements?

[bdewoody]

How many cycles of star formation does it take before significant amounts of the heavy elements are created? For instance, how many generations of stars needed to have run to provide the elements that are present in our system? <div class="Discussion_UserSignature"> <em><font size="2">Bob DeWoody</font></em> </div>

 

[docm]

Until a large star goes supernova or a smaller star like the sun blows off its outer layers. Accumulations of the debris provides the raw materials for complex solar systems, plus its thought that a supernova shock wave provides the impetus that causes proto-stars to form in interstellar clouds. <div class="Discussion_UserSignature"> </div>

 

[heyscottie]

The sun is considered a "2nd generation" star.

 

[yevaud]

The two other mechanisms are Big-Bang Nucleosynthesis (significant amounts of heavy elements created during the BB), and Stellar Nucleosynthesis (continual creation of amounts of heavy elements in each star). <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[lukman]

I dont know how it is related, but the present of heavy element in a star is not good for the star itself, star may only consist light element like helium and hidrogen, right? <div class="Discussion_UserSignature"> </div>

 

[heyscottie]

That is more or less true. Fusion of elements to a product heavier than iron consumes rather than releases energy. A star with a large percentage of heavier elements will not live as long, as it will not have as much fusable fuel.

 

[majornature]

How was that determine the sun's generation. I need more details. <div class="Discussion_UserSignature"> <font size="2" color="#14ea50"><strong><font size="1">We are born.  We live.  We experiment.  We rot.  We die.  and the whole process starts all over again!  Imagine That!</font><br /><br /><br /><img id="6e5c6b4c-0657-47dd-9476-1fbb47938264" style="width:176px;height:247px" src="http://sitelife.space.com/ver1.0/Content/images/store/14/4/6e5c6b4c-0657-47dd-9476-1fbb47938264.Large.jpg" alt="blog post photo" width="276" height="440" /><br /></strong></font> </div>

 

[heyscottie]

The fact that the sun's metallic content is relatively high, and that its protoplanetary disc clearly contained enough heavy elements to allow formation of rocky planets shows that it must be a second generation star formed at least in part from the ashes of earlier supernovae.

 

[nexium]

If you prefer, you can think of our sun as third or 4 th generation. I don't see anything compelling about second. Some stars were born 8 billion years before our sun so 3 generations of O, B, and A stars could have provided most of the heavy elements in our solar system. Neil

 

[heyscottie]

I've not really heard a distinction made between 2nd and higher generations. Generally, a star seems to be classified as first or second generation, which means "not first generation", at least as far as I have seen.

 

[yevaud]

That would be precisely correct. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>

 

[Saiph]

the distinction between generations as I'm familiar with it is:<br /><br />1st: Pure hydrogen helium stars, the primordial first stars. We've found a couple of stars very close to this.<br /><br />2nd: Low, low metal content, basically the first stars formed after the primordial giants died. These tend to be the older stars in globular clusters (among other places).<br /><br />3rd: "modern" stars, with significant metal contents. Massive O & B stars actually require a significant metal content in order for their particular brand of fusion to work (the CNO cycle uses C, N, and O atoms as catalysts). <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>

 

[MeteorWayne]

Saiph, long time no see!<br /><br />Glad we are around a "modern" star, or we wouldn't be here <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[heyscottie]

Thanks.<br /><br />And it's good to see you again!