I'm sure I've mis-used the terms Pop. I and Pop. II stars. What I intended to convey was the concept of the first generation of stars vs. stars that coalesced more recently. IIRC, the first stars to form in the universe had no metalicity. Could they even blow-off an envelope of sulfur, oxygen, iron, and other heavier elements to form a planetary nebula? Assuming they were small enough in mass to fall below the Chandresekhar limit of 1.4(?) solar masses; I had thought that first generation of stars were predominantly massive giants- their end product would be neutron stars or black holes. This is what was making me think that white dwarfs form from a later generation of stars with a higher percentage of heavy elements, such as the sun- which has only been around for something like 1/3 of the lifetime of the solar system.