Question

A planetary nebula is created

A) over several hundred years, during mass transfer in a close binary star system.
B) over a few thousand years or more, in a slow expansion away from a low-mass star, driven by a series of thermal pulses from helium fusion.
C) in hours or less, during the explosion of a massive star.
D) in seconds, during the helium flash in a low-mass star

Answer 1

Planetary nebulae are created in a slow expansion away from low-mass stars driven by thermal pulses from helium fusion. Hence, the correct answer is option B.

Step-by-step explanation:

A planetary nebula is created in a slow expansion away from a low-mass star, driven by a series of thermal pulses from helium fusion.

As stars evolve, they swell up to become red giants. These red giants have very large radii and low escape velocities. At this stage, radiation pressure, pulsations, and events like the helium flash drive atoms in the outer atmosphere away from the star, causing it to lose a substantial fraction of its mass into space. This mass loss leads to the formation of one or more expanding shells of gas, known as planetary nebulae. These shells are made up of the ejected material from the star, and they expand away from the star over a few thousand years or more.