Algol consist of a 3.7 MSun main-sequence star and a 0.8 MSun subgiant. Why does this seem surprising, at least at first?
A. The two stars in a binary system should both be at the same stage of life; that is, they should either both be main-sequence stars or both be subgiants.
B. It doesn't make sense to find a subgiant in a binary star system.
C. The two stars should be the same age, so we'd expect the subgiant to be more massive than the main-sequence star.
D. A star with a mass of 3.7 MSun is too big to be a main-sequence star.
Answer:C
Algol consist of a 3.7 MSun main-sequence star and a 0.8 MSun subgiant. Why does this seem surprising, at least at first?
A. The two stars in a binary system should both be at the same stage of life; that is, they should either both be main-sequence stars or both be subgiants. B. It doesn't make sense to find a subgiant in a binary star system. C. The two stars should be the same age, so we'd expect the subgiant to be more massive than the main-sequence star. D. A star with a mass of 3.7 MSun is too big to be a main-sequence star.