, ▁forming ▁about ▁ 9 8 % ▁of ▁its ▁mass . ▁The ▁remaining ▁ 2 % ▁of ▁the ▁mass ▁consisted ▁of ▁heav ier ▁elements ▁that ▁were ▁created ▁by ▁nucle os yn thesis ▁in ▁earlier ▁gener ations ▁of ▁stars . ▁Late ▁in ▁the ▁life ▁of ▁these ▁stars , ▁they ▁e ject ed ▁heav ier ▁elements ▁into ▁the ▁inter stell ar ▁medium . ▁ ▁The ▁oldest ▁inclus ions ▁found ▁in ▁meteor ites , ▁thought ▁to ▁trace ▁the ▁first ▁solid ▁material ▁to ▁form ▁in ▁the ▁pres olar ▁ne b ula , ▁are ▁ 4 5 6 8 . 2   mill ion ▁years ▁old , ▁which ▁is ▁one ▁definition ▁of ▁the ▁age ▁of ▁the ▁Sol ar ▁System . ▁Studies ▁of ▁ancient ▁meteor ites ▁reve al ▁traces ▁of ▁stable ▁daughter ▁nuc lei ▁of ▁short - l ived ▁is ot op es , ▁such ▁as ▁iron - 6 0 , ▁that ▁only ▁form ▁in ▁expl oding , ▁short - l ived ▁stars . ▁This ▁indicates ▁that ▁one ▁or ▁more ▁super nov ae ▁occurred ▁near ▁the ▁Sun ▁while ▁it ▁was ▁forming . ▁A ▁shock ▁wave ▁from ▁a ▁super n ova ▁may ▁have ▁triggered ▁the ▁formation ▁of ▁the ▁Sun ▁by ▁creating ▁relatively ▁dense ▁regions ▁within ▁the ▁cloud , ▁causing ▁these ▁regions ▁to ▁collapse . ▁Because ▁only ▁massive , ▁short - l ived ▁stars ▁produce ▁super nov ae , ▁the ▁Sun ▁must ▁have ▁formed ▁in ▁a ▁large ▁star - form ing ▁region ▁that ▁produced ▁massive ▁stars , ▁possibly ▁similar ▁to ▁the ▁Or ion ▁Neb ula . ▁Studies ▁of ▁the ▁structure ▁of