(a(i))[1]
State what the luminosity of a star means.
(a(ii))[3]
Explain how standard candles are used to find the distance to a galaxy.
(b)
The Sun spins about its axis. The points X, Y and Z lie on the Sun’s equator, as shown in Fig. 10.1. The wavelengths of the light from points X and Y are measured and tabulated in Table 10.1.
(b(i))[3]
The Sun has a rotation period of $2.07 \times 10^{6}\ \text{s}$. Show that the Sun’s radius is $6.93 \times 10^{8}\ \text{m}$.
(b(ii))[2]
State and explain how the wavelength of the light observed from Z is expected to compare with the emitted wavelength.
(b(iii))[2]
The Sun’s luminosity is $3.8 \times 10^{26}\ \text{W}$. Use the data in (b)(i) to work out the surface temperature of the Sun.