Stellar Evolution and Death -- The Ejection of Planetary Nebulae

Stellar Evolution and Death header

2. The Ejection of Planetary Nebulae

The evolution and eventual fate of stars in the late stages of their lives are critically dependent on the amount of matter they have at birth:

Stars with initial masses of less than about eight solar masses end their lives by ejecting planetary nebulae. The stellar remnants are white dwarfs.
Stars with initial masses greater than about eight solar masses end their lives by exploding as supernovae. The stellar remnants are neutron stars or black holes.

In this section, we discuss the evolution and final fate of stars that form planetary nebulae. In the next section, we'll discuss the evolution and final demise of the more massive stars:

Planetary Nebula Formation
Central Stars of Planetary Nebulae

The Ring Nebula

The Ring Nebula in the constellation Lyra was the first planetary nebula discovered. The discoverer, Antoine Darguier, described it in 1779 as being "as large as Jupiter and resembling a fading planet." It is this resemblance to planets viewed through small telescopes that gave rise to the label "planetary nebulae," even though they have nothing to do with planets.

The Ring Nebula is a nearly spherical shell of gas with a diameter of slightly less than two light-years. It lies at a distance of 5,500 light-years. The whitish star at its center is the progenitor star.

Image Credit: Nordic Optical Telescope.

Back Next
Back to Contents