Passage VI
A star's brightness is described by its magnitude. As magnitude increases, brightness decreases. A star's apparent magnitude is measured from Earth. A star's absolute magnitude is the magnitude that would be measured 10 parsecs from the star (1 parsec [pc] = 3.1 x 1016 m). V represents the apparent magnitude of a star's visible light. MV and MB represent the absolute magnitudes of a star's visible light and blue light, respectively.
Table 1 lists V, MV, V - MV, and MB - MV for particular stars in each of 4 hypothetical star clusters (SCs). Figure 1 shows SC age versus MB - MV. Figure 2 shows SC distance from Earth versus V- MV. Table 2 lists a star's power output of visible light for a given MV.
34. As MB - MV increases, stellar surface temperature decreases. Based on Table 1, is the surface temperature lower for the particular stars in SC III or for the particular stars in SC IV ?
Your Answer is
Correct Answer is J
Explanation
If you want to know which one has the lower temperature, SC III or SC IV, you have to look at which has a higher MB-MV value, so see table 1 shows that SV IV is bigger, so the temperature is lower