Question

What would you need to measure about a planetary nebula (see the image below) to determine how long ago its parent star died?

1) The mass of the white dwarf
2) The mass and radius of the white dwarf
3) The nebula's radius and expansion velocity
4) The nebula's temperature and radius

Answer 1

To determine how long ago a parent star died, you would need to measure the nebula's radius and expansion velocity.

Step-by-step explanation:

To determine how long ago a parent star died, you would need to measure the nebula's radius and expansion velocity. By knowing the expansion velocity and assuming it has been constant, you can use the equation distance = velocity x time to calculate the time it took for the gas to leave the star. The radius of the nebula is also important for understanding the size and stage of the star's evolution.