An observer on Earth measures the apparent brightness of two luminous stars

PHYSICS · Single correct · A Level · Physics · Astrophysics · Astrophysics

Problem

An observer on Earth measures the apparent brightness of two luminous stars. • Star A: radius

1.5R_{\odot}

, surface temperature

7000\,\text{K}

, distance

10\,\text{pc}

. • Star B: radius

3.0R_{\odot}

, surface temperature

5000\,\text{K}

, distance

40\,\text{pc}

. Which statement correctly describes which star appears brighter to the observer and by approximately what factor? (a) Star A appears brighter, by roughly

15

times. (b) Star A appears brighter, by roughly

4

times. (c) Star A appears brighter, by roughly

8

times. (d) Star B appears brighter, by roughly

17

times.

Related theory

Stellar Physics
Heat Transfer

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