Exam-style question
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A star has a brightness measured at Earth of 10^-6 W/m². What does this indicate about the star's luminosity compared to a star with a brightness of 10^-4 W/m²?.
Model answer
What a good answer should say
- The star with a brightness of 10^-6 W/m² is less luminous than the star with a brightness of 10^-4 W/m².
- This is because luminosity is the total power output of a star, and a higher brightness at Earth indicates a higher luminosity.
Explanation
Why this works
The evidence shows that the brightness values are significantly different, with the second star being 100 times brighter. This indicates that luminosity is directly related to brightness as observed from Earth.
The implication is that the first star must either be further away or inherently less powerful than the second star. Thus, we conclude that luminosity is a key factor in understanding a star's characteristics.
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