Which of the following statements is true of the spectral sequence?
A) It is classified in groups labeled A through Q.
B) M stars are cooler and fainter than L dwarfs.
C) Y dwarfs are a class of objects with temperatures above 500 K.
D) O stars are the hottest, and M stars are the coolest.
Question 2
In the context of main-sequence stars, which of the following statements is true of a mass-luminosity relation?
A) The main-sequence stars in a Hertzsprung-Russell diagram are not ordered according to their masses.
B) The lowest-mass stars are the hottest and brightest main-sequence stars.
C) It is followed by giants, supergiants, and white dwarfs.
D) The more massive a star is, the more luminous it is.
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