Suppose a white dwarf is gaining mass because of accretion from a binary companion. what happens if its mass reaches the 1.4 solar mass limit?

The white dwarf undergoes a catastrophic collapse, leading to a type of supernova that is somewhat different from that which occurs in a massive star but is comparable in energy.

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multiple allele inheritance is traits controlled by more than 2 alleles (ex: pigeons having 3 alleles of one gene govern their feather color).