(6) (2 + 2 = 4 points.) Suppose Blackhody Edgar peaks at 9,000 A. Blackhody Neil, of the same surface area, peaks at 3,000 A. (a) (2 points.) Which one emits more radiation per second at 3,000 A? (b) (2 points.) Which one emits more radiation per second at 9,000 A? (Again, note that 10 A = 1 nm, in case you prefer 11111.) (7) (3 points.) If a star has a surface temperature three times higher than that of the Sun, and a radius four times that of the Sun, by what factor is the star more luminous than the Sun? (8) (2 + 2 = 4 points.) (a) (2 points.) What is the distance of a star whose parallax is 0.03 seconds of arc? (b) (2 points.) What is the parallax of a star whose distance is 150 pc? (9) (3 points.) If the Sun were 25 times farther from us than it is, how bright would it appear to be, relative to its current brightness? (10) (3 points.) Suppose you nd a binary system in which one star is 5 times as massive as the other star. Which one is closer to the center of mass, and by what factor? (11) (2 + 2 = 4 points.) (a) (2 points.) If main-sequence star Alex is four times as massive as main- sequence star Savannah, what is the ratio of their luminosities? (b) (2 points.) What is the ratio of their main-sequence lifetimes? Be sure to state which one is more luminous and which one lives longer