* For stars less massive than the Sun (less than 0.5 solar masses): The red giant phase is followed by the planetary nebula stage. In this stage, the star's outer layers are ejected into space, creating a beautiful, expanding shell of gas. The remaining core collapses into a white dwarf, a dense, hot remnant that slowly cools over billions of years.
* For stars similar to the Sun (0.5 to 8 solar masses): The red giant phase is followed by the horizontal branch stage, where the star briefly stabilizes before becoming a asymptotic giant branch (AGB) star. This stage is marked by a second period of expansion and cooling. Finally, after a final pulse of mass loss, the star forms a planetary nebula and leaves behind a white dwarf.
* For stars more massive than the Sun (8 to 25 solar masses): These stars skip the horizontal branch and AGB stages and directly enter the supergiant phase. They eventually experience a supernova explosion, leaving behind either a neutron star or a black hole.
So, while planetary nebula is the most common next stage after red giant for stars like our Sun, the path can vary depending on the star's mass.
