Space Telescope Science Institute

Sun-like stars reach the end of their lives after they have consumed most of the hydrogen in their cores. They enter the red giant phase of their life, and eventually collapse into a white dwarf. During this transition, these stars often eject a shell of thin matter that forms a planetary nebula. These are some of the most beautiful and unusual looking objects in the Universe. Many show symmetric lobes like an hourglass which form at the poles of the star.

How do planetary nebulae form?

This movie combines scientific images with an artist's imagination, showing one possible mechanism for the formation of these types of planetary nebulae. A key clue comes from the gas flowing out from the center of the nebula. The gas is ejected in what astronomers call jets at over 700,000 miles per hour (1.1 million kilometers per hour). From telescopic observations, we also know that the central star in some of these nebulae is one of a very closely orbiting pair; one star may even be engulfed by the other's gaseous stellar atmosphere.

Forming jets

Astronomers theorize that the gravity of one star pulls some of the gas from the surface of the other and funnels it into a thin, dense disk extending into space. The disk acts like a nozzle, pushing the stellar wind into the jets. This is similar to the process that takes place in a jet engine on a commercial airliner.

Gordon Myers