What is the glowing shell of gas ejected from a low- to medium-mass star at the end of its life called?

What is the glowing shell of gas ejected from a low- to medium-mass star at the end of its life called?

• A. Nebula
• B. Accretion disk
• C. Supernova remnant
• D. Planetary nebula

Answer: (D)

Low- to intermediate-mass stars shed their outer layers at the end of their lives, and the ejected gas forms a glowing shell around the hot core. The central remnant emits ultraviolet radiation that ionizes this gas, causing it to glow in emission lines. This specific glowing shell is called a planetary nebula. The name is historical and not related to planets. Nebula is a general term for any interstellar cloud, while a planetary nebula is a particular type produced by these stars. A supernova remnant comes from the explosive death of a massive star, and an accretion disk is material orbiting a compact object, not a shell ejected by a dying low- to intermediate-mass star.

Low- to intermediate-mass stars shed their outer layers at the end of their lives, and the ejected gas forms a glowing shell around the hot core. The central remnant emits ultraviolet radiation that ionizes this gas, causing it to glow in emission lines. This specific glowing shell is called a planetary nebula. The name is historical and not related to planets. Nebula is a general term for any interstellar cloud, while a planetary nebula is a particular type produced by these stars. A supernova remnant comes from the explosive death of a massive star, and an accretion disk is material orbiting a compact object, not a shell ejected by a dying low- to intermediate-mass star.