What would you need to measure about a planetary nebula to determine how long ago its parent star died?

Question

Quizplus · Accepted Answer

To determine how long ago a planetary nebula's parent star died, we need to measure the nebula's radius and expansion velocity. This would allow us to calculate how long it has taken for the nebula to expand to its current size, providing an estimate of the age of the system. The mass and radius of the white dwarf can give us information about the star that formed the planetary nebula, but not necessarily its age. The nebula's temperature may provide some clues about its composition and evolution, but it is not a direct measure of the star's age.

What Would You Need to Measure About a Planetary Nebula