How long can a planetary nebula remain visible?

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Planetary nebula Southern Ring Nebula as captured by the James Webb Space Telescope in the near-infrared (left) and the mid-infrared (right). The dimmer star at the center of this scene has been sending out rings of gas and dust for thousands of years in all directions. The Southern Ring Nebula is approximately 2,500 light-years away.

A planetary nebula remains visible for a relatively brief period compared to the lifetime of its parent star. As the nebula expands, its gas becomes increasingly dilute.12

The visibility of the nebula depends on the central star providing enough ultraviolet radiation to keep the gas ionized. Eventually, the star becomes less luminous and can no longer maintain this ionization, causing the outer regions of the nebula to become neutral and invisible.13

Typically, these objects remain observable for up to approximately 30,000 years after ejection. Beyond this timeframe, the nebula becomes so tenuous that it can no longer be distinguished from the surrounding interstellar gas, with which it eventually merges.23