(a(i))[2]
State the meaning of the luminosity of a star.
(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(i))[2]
The Sun has a radius of $6.96 \times 10^{8}\,\text{m}$ and a surface temperature of $5780\,\text{K}$. Radiation from the Sun is observed to peak at a wavelength of $501\,\text{nm}$. Calculate the luminosity of the Sun. Include a unit in your answer.
(b(ii))[2]
A different star gives radiation with a peak intensity at a wavelength of $624\,\text{nm}$. Determine this star’s surface temperature.