The figure below is an incomplete Hertzsprung-Russell (HR) diagram of stars.
a.[2]
State the type of stars found in regions X and Y.
b.[3]
Sirius A is a main-sequence star. Its surface temperature is 9900 K and the wavelength of the emitted light at maximum intensity is 293 nm293\text{ nm}293 nm. 61 Cygni B is also a main-sequence star. The wavelength of the emitted light at maximum intensity from this star is 720 nm720\text{ nm}720 nm.
Calculate the surface temperature of 61 Cygni B. Give your answer to 3 significant figures.
c.[2]
State and explain whether the position of 61 Cygni B on the HR diagram is to the left or to the right of Sirius A along the main sequence.