I ran across some article that pointed to this research: http://www.omatumr.com/picpages/snexplo.html The theory states that Sun formed from accretion of supernova remnants back into/onto its core. Now, my scientific background is quite limited but this theory seems to me more realistic than an idea that a near supernova contributed to such large amount of heavy elements in our solar system. The theory would then maybe make more sense into observations that gaseous planets are generally found much closer to their stars because I assume that most other stars do not form in such way. If this turned out to be an accepted theory it would limit the amount of possible candidates for intelligent civilizations because it may imply that only such events generate enough heavy element to sustain civilizations. Also, I would like to get some clarification to what happens to a SN core usually. Wikipedia states that under 20 solar masses on SN type II you get a neutron star, which contradicts with the theory.