Final answer:
The lifetime of a star depends primarily upon its mass. Massive stars have shorter lifetimes than low-mass stars because they burn their fuel faster.
Step-by-step explanation:
The lifetime of a star depends primarily upon its mass. Massive stars have shorter lifetimes than low-mass stars because they burn their fuel faster. The more massive a star is, the more fuel it has to burn, but it also uses up the fuel at a faster rate. Therefore, the mass of a star determines how long it will shine and what its ultimate fate will be.
Additionally, the chemical composition of a star can affect its lifetime to some extent. However, the primary factor is the star's mass.
Size or the object's shape are not the primary determinants of a star's lifetime.