What is a planetary nebula?
A)the expanding shell of gas that is no longer gravitationally bound to the remnant of a low- mass star
B)the expanding shell of gas that is left when a white dwarf explodes as a supernova
C)the molecular cloud from which protostars form
D)a disk of gas surrounding a protostar that may form into planets
E)what is left of its planets after a low- mass star has ended its life

Question

Quizplus · Accepted Answer

A planetary nebula is the expanding shell of gas that is no longer gravitationally bound to the remnant of a low-mass star. As the star runs out of fuel, it will shed its outer layers into space, creating a nebula that can be observed. The inner core of the star will collapse down to form a white dwarf.

What Is a Planetary Nebula