What would you need to measure about a planetary nebula to determine how long ago its parent star died?
A) the mass of the white dwarf
B) the mass and radius of the white dwarf
C) the nebula's temperature and radius
D) the nebula's radius and expansion velocity
E) the composition of the gas in the nebula

Question

Quizplus · Accepted Answer

By measuring the radius and expansion velocity of the planetary nebula, astronomers can calculate how long ago the nebula was formed. This information can be used to determine the age of the parent star at the time of its death. The other options may be useful for other studies of planetary nebulae but do not provide information on the age of the parent star.

What Would You Need to Measure About a Planetary Nebula