Figure 12-3Evolution from Red Supergiants to White Dwarfs The evolutionary tracks of three intermediate-mass supergiants are shown as they eject planetary nebulae. The table gives their masses as supergiants, the amount of mass they lose as planetary nebulae, and their remaining (white dwarf) masses. The loops indicate periods of instability and adjustment for the white dwarfs. The dots on this graph represent the central stars of planetary nebulae whose surface temperatures and luminosities have been determined. The crosses are white dwarfs for which similar data exist.