Exam-style question
Try this first
If a star's apparent brightness is measured at 5 x 10^-5 W/m² and its distance from Earth is 10 parsecs, how would you interpret this data in terms of its luminosity?.
Model answer
What a good answer should say
- To interpret the luminosity, we can use the inverse-square law of brightness.
- The luminosity can be calculated as L = 4πd²B, where d is the distance in meters and B is the apparent brightness.
- Given the distance of 10 parsecs (1 parsec = 3.086 x 10^16 m), the luminosity will be significantly high due to the distance factor.
Explanation
Why this works
The evidence shows the apparent brightness and distance, which are crucial for calculating luminosity. This indicates that the star's luminosity is influenced by its distance from Earth, as brightness decreases with distance.
The implication is that a star can appear dimmer if it is far away, even if it is intrinsically luminous. Therefore, we conclude that understanding both brightness and distance is essential for accurately interpreting a star's luminosity.
Common mistake
No common mistake is linked to this question yet.