# [6] What is the Luminosity of a star with a radius of 7.50 X 10A11 m and a surface temperature of 3000 K? Answer: 3.25 X 10A31 W Student Responsible

I populated L with 3.25×10^31 W and B with 10^-3 W/m^2, however the answer I get is nowhere near 5.09 x 10^16. I’ve also tried using the formula below.

I populated Lsun with the constant from the chart below, 3.83×10^26 W and attempted to calculate the apparent brightness of the sun using the constant for 1 AU and the inverse square law, and using the constant for Lsun… I got bsun=1354.6. So I used bsun in the aforementioned formula and got nowhere near the right answer. I also don’t have a reference to calculate magnitude and use cepheids… so I’m not sure what I’m supposed to do here. I really don’t even need an answer handed to me, but some guidance and explanation would help.

The below image shows the constants that may be used, I posted the formulas I’ve tried above.

- Attachment 1
- Attachment 2

[6] What is the Luminosity of a star with a radius of 7.50 X 10A11 m anda surface temperature of 3000 K? Answer: 3.25 X 10A31 W Student Responsible for Posting Solution: [7] Find the distance to the star in Problem #6 if the apparent brightnessof that star is 10A-3 W/mAZ? Answer: 5.09 x 10A16 m, 5.38 Ly Student Responsible for Posting Solution: