Describe the life cycle of a star that is similar in size to the Sun, starting from a nebula. Include the names of each stage and the key processes involved.

A nebula (cloud of dust and gas) collapses under its own gravity to form a protostar.
The protostar contracts until core temperatures reach ~10^7 K, igniting hydrogen fusion and entering the main‑sequence stage where outward radiation pressure balances gravity.
When core hydrogen is exhausted, the core contracts, heating the shell and the outer layers expand, producing a red giant that fuses helium and heavier elements.
Fusion eventually ceases; the core collapses and the outer layers are shed, leaving a hot core that cools and contracts into a white dwarf.
The correct sequence is: nebula → protostar → main‑sequence star → red giant → white dwarf.