Planetary Nebula NGC 3918
Depicts: NGC 3918, IRAS 11478-5654
Copyright: Robert Rubin (NASA Ames Research Center), Reginald Dufour and Matt Browning (Rice University), Patrick Harrington (University of Maryland), and NASA
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Studying images of proto-planetary nebulae is important to understanding
the process of star death. A star begins to die when it has exhausted
its thermonuclear fuel - hydrogen and helium. The star then becomes
bright and cool (red giant phase) and swells to several tens of times
its normal size. It begins puffing thin shells of gas off into space.
These shells become the star's cocoon. In the Hubble images, the shells
are the concentric rings seen around each nebula.
Last Update: 1 September 2019