Two stars, one classified A4 V and the other A4 III, have the same apparent magnitude. There is no significant amount of absorption of starlight by interstellar material. From this information one knows that the A4 V star is _____ than the A4 III star.

Question

Quizplus · Accepted Answer

The A4 V star is closer to the Sun than the A4 III star because the Roman numeral V indicates a main sequence star, which is less luminous than a star classified as III, a giant star. Since both stars have the same apparent magnitude but the giant star is inherently more luminous, the main sequence star must be closer to compensate for its lower luminosity.

Two Stars, One Classified A4 V and the Other A4