(a(i))[2]
State what the luminosity of a star means.
(a(ii))[3]
Explain how a standard candle in a distant galaxy can be used to find the galaxy’s distance from an observer.
(b)
The Sun’s radius is $6.96 \times 10^{8}\,\text{m}$ and its surface temperature is $5780\,\text{K}$. The Sun’s light is observed to have peak intensity at a wavelength of $501\,\text{nm}$.
(b(i))[2]
Calculate the Sun’s luminosity. Include a unit in your answer.
(b(ii))[2]
A different star has radiation with a peak intensity at a wavelength of $624\,\text{nm}$. Determine this star’s surface temperature.