The image shows the planetary nebula IC 289, located in the northern constellation of Cassiopeia. Formerly a star like the sun, it is now just a thin cloud of ionized gas being pushed out into space by the remnants of the star's core, visible as a small bright dot in the middle of the cloud, NASA said Friday.
Planetary nebulae have nothing to do with planets -- the term is a relic from a time when early observers with small telescopes could only see undefined, hazy objects they thought looked like gaseous planets.
Stars are powered by nuclear fusion reactions in their cores that convert hydrogen to helium. The star remains stable in a process that balances the inward squeeze caused by its gravity with the outward thrust from the inner fusion reaction in its core.
When all the hydrogen is consumed, as in IC 289, the equilibrium is broken. The gravitational forces become more powerful and crush the star's core into a helium-burning phase that is highly unstable, and eventually blows the whole star's atmosphere away, resulting in the state captured in the Hubble image.