of C,N,0 



rm 



( from diffuse 



Ejection of new 

 nuclides to the rA 

 interstellar W 

 medium 





XT 



chemistry _n 

 in dense L> 

 interstellar ^ 

 clouds 



Creation' of : 

 7H?He uxx " 



Collgpse L c/ . 

 cloud material 

 to form solar 

 System 



chemistry in 

 the nebufc 



Incorporation^— 

 of bioqenic elements: 



chemist™ durinq 

 entry into ma 



-. ^ 



\-J cKSniSMf 



during collapse 



in nockM 

 esw 



Reentry of 

 some/'iCH/ , 

 Xn icu ^Eiection x ptoetesiflttis 



planeteslmals" planetfesimals Qfrom Das comets 

 in inner solar in outer solar v solar ^ //// 

 ^system • system sustem /// 



• Vl • do JJ4 



i >C incorporation of . 



chemistru mQst v>ianetesimate 



during internal ineuanets p. nr ,p tnnj 



heating of 0^[A G P ^ r r 



Preservation of # # rA Fraqments of asteroids 



some material L/ r„,rt^ „„ +u 



from this stage ^ tall to earth 



as asteroids os meteorites 



F/gure 3-7. The cosmic history of the biogenic elements and compounds— from 

 the Big Bang to the formation of planets. 



21 



