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How does dust inside a planetary nebula reveal itself to astronomers?
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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.
In the context of planetary nebulae, dust generally cannot be observed directly. Instead, it reveals its presence to astronomers through the infrared radiation it emits after being heated by the surrounding nebular and stellar radiation.1
While some planetary nebulae contain this internal dust, it is often difficult to detect because it is obscured by other materials or simply does not emit visible light. By measuring infrared emissions, astronomers can confirm the presence of dust, which also serves as an indicator that these nebulae are more enriched in heavy elements than studies of the gas phase alone might suggest.12