Question

Stars change considerably during their lifetimes. The process through which they change is known as stellar evolution. Since stellar evolution occurs too slowly to be detected, scientists often study numerous stars in different phases of their lives to infer what happens to them over time.

One observation that scientists have made is that the initial mass of a star determines its evolution. How does the evolution of a low-mass star differ from that of a more massive star?
A.
Low-mass stars develop more slowly than more massive stars; their lifetimes can last trillions of years as opposed to only a few million years.
B.
Stars with masses less than 1.6 × 1029 kg become brown dwarfs because they are unable to reach high enough temperatures for hydrogen fusion to take place.
C.
Extremely massive stars are able to produce supernovas, or stellar explosions, when they cease to undergo nuclear fusion or when they undergo a sudden gravitational collapse.
D.
all of the above

Answer 1

D.

All three statements are correct:
- Low-mass stars (especially red dwarfs) evolve much more slowly and can live for trillions of years, whereas very massive stars exhaust their fuel in millions of years.
- The hydrogen-fusion minimum mass is about 0.08 M☉ ≈ 1.6 × 10^29 kg; objects below this become brown dwarfs.
- Very massive stars can end their lives in core-collapse supernovae when fusion stops and the core undergoes sudden gravitational collapse.