Abstract
Stars with masses of less than 8 solar masses do not have sufficient temperature to ignite carbon fusion, and end their lives as white dwarfs, compact cores after ejection from their envelopes in planetary nebulae. The core is stabilized against gravitational collapse by the Pauli quantum pressure, where electrons are degenerated. Recently, GAIA has been able to identify the various stages of white prenasae in the HR diagram. Planetary nebulae have very varied morphologies, and their size and ionized oxygen lines make them a valuable tracer of potential in galaxies.
