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June 2003

Planetary Nebulae - Stellar Death Shrouds

These images show four fine examples of "planetary nebulae" - glowing gas that surrounds a very hot compact stars that represents the distant future of our Sun.

Once stars like our Sun have exhausted all of their available fuel, they expand to huge diameters (as big as the orbit of the Earth). Then, their outer layers are gently ejected into space. The remnant hot core energizes the surrounding gas, producing the planetary nebula. This is a very brief phase - lasting just 100,000 years, after which the nebula disperses and the core cools. In these images, the greenish tinge is given by the light of glowing oxygen gas, while red signifies the light from hydrogen.

These four examples show the variety of shapes and sizes that planetary nebulae can display. The reason why they are so asymmetrical remains a mystery... the solution to which will give us details on the circumstances surrounding their central stars' demise.