Betelgeuse in the constellation of Orion is a red supergiant star.

(i) Compare the fate of Aldebaran to that of Betelgeuse.

(ii) Outline, with reference to the Chandrasekhar limit, the circumstances under which the final state of Betelgeuse could be the same as the final state of Aldebaran.

Distances to galaxies may be determined by using Cepheid variable stars.

By considering the nature and properties of Cepheid variable stars, explain how such stars are used to determine galactic distances.

(i) Aldebaran:
it forms a planetary nebula which then becomes a white dwarf;
Betelgeuse:
it forms a supernova which then becomes a neutron star/black hole/pulsar; 
To award [2] both phases are required in both responses.
Award [1 max] if intermediate stages (planetary nebula, supernova) are omitted.

(ii) reference to 1.4 solar mass (Chandrasekhar limit for white dwarfs);
if Betelgeuse blows away sufficient mass (in the supernova stage);
and is left with a core mass below the Chandrasekhar limit;
the core can form a white dwarf

the (outer layers of the star) undergo a (periodic) expansion and contraction;
which produces a (periodic) variation in its luminosity/apparent brightness;
the (average) luminosity depends on the period of variation;
by measuring the period, the luminosity can be found;
by then measuring its apparent brightness, its distance from Earth can be found;