So, how far from a “normal” supernova do you have to be to avoid burning up/burning out the local atmosphere of your own planet?
How many supernova’s are required to create each of the common elements? A “regular” and a regular nova burns (combines) H-H->He, He_> Li and higher as it implodes later in life, and a little bit higher weight .. But those cannot leave the star. They are trapped inside the star’s gravity field.
So, only a supernova cab low elements (isotopes) outside to another star. Can a supernova create several tiers of element-isotope building in its own collapse?
Or are we limited by stellar fusion to “one-nuclei+one-nuclei fusion mass gain per supernova?
The heavier elements were (in the various closely related commonly discussed model of formation) built in the activity of early stars, pretty much all of which have ceased to exist.
Theory says if there's a supernova in your stellar neighborhood, you might as well kiss your behind goodbye. All of the planets in the star's orbitary family will be cinders. Any nearby stars will be washed with deadly radiation for several tens of light years, perhaps even up to a couple of hundred light years. Lesser radiation will have deleterious mutational effects even farther away, say several thousand light years.
Every time scientists, and especially astrophysicists, think they have all the answers, God throws them a curve ball..............................