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Hubble Space Telescope Witnesses the
Final Blaze of Glory of Stars Like Our Sun
The end of a Sun-like star's life was once thought to be simple. The star gracefully would cast off a shell of glowing gas and then settle into a long retirement as a burned-out white dwarf.
However, a dazzling new collection of detailed views of stars strewn across deep space reveals surprisingly intricate glowing patterns spun into space by aging stars -- pinwheels, lawn-sprinkler style jets, elegant goblet shapes, and even some that look like a rocket engine's exhaust. The breathtaking pictures were made by teams of astronomers using NASA's Hubble Space Telescope.
The eerie fireworks offer a preview of the final stage of our own Sun's life. More than simply a stellar light show, the stars' outbursts provide a way for heavier elements -- mostly carbon cooked in the stars' cores -- to be ejected into interstellar space as raw material for successive generations of stars, planets and life.
The astronomers say the incandescent sculptures have forced them to re-think stellar evolution. In particular, the star outburst patterns may be woven by an aging star's interaction with unseen companions, such as planets, brown dwarfs or smaller stars.
Surprising new details revealed by the Hubble pictures include:
How do these nebulae shape themselves? A long-standing puzzle is how they acquire their complex shapes and symmetries. The red giant stars that preceded their formation should have ejected simple spherical shells of gas. Hubble's ability to see very fine structural details -- usually blurred beyond recognition in images made by telescopes on Earth -- enables astronomers to look for clues to the puzzle.
- Unexplained disks and donuts of dust girdling a star and pinching outflowing gas. They may be linked to the presence of invisible companions.
- Remarkably-sharp inner bubbles of glowing gas -- like a balloon inside a balloon -- blown out by the violently outflowing gases called a "fast wind" (1000 miles/second) ejected during the final stages of a star's death.
- Strange glowing red blobs placed along the edge of some nebulae may be chunks of older gas caught in the stellar gale of hot material flowing from the dying star.
- Jets of high-speed particles that shoot out in opposite directions from a star, and plow through surrounding gas, like a garden hose stream hitting a sand pile.
- Pinwheel patterns formed by symmetrical ejection of material so that intricate structures are mirrored on the opposite side of a star.
New instruments for recording infrared light were installed on the Hubble Space Telescope in February 1997. Several teams of astronomers, using those instruments to observe planetary nebulae, are able to glimpse the ejection of material at a very early stage long before the expelled nebula starts to become visible optically.
Given Hubble's high resolution, astronomers hope to revisit the same nebulae in a few years to see how their shells have expanded farther into space. Those observations will be compared with predictions to refine or dismiss ideas on the mass ejection mechanisms of dying stars.
The nebulae observed by Hubble give astronomers a preview of our own Sun's fate. Five billion or so years from now, after our Sun has become a red giant and burned the Earth to a cinder, it will eject its own beautiful nebula and then fade away as a white dwarf star.
The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency (ESA). The Space Telescope Science Institute (STScI) at Baltimore is operated for NASA by the Association of Universities for Research in Astronomy, Inc. (AURA) under contract with the Goddard Space Flight Center, Greenbelt, Maryland.
Images of these exploding stars are available on the World Wide Web at:
Dying Star Becomes a Diamond »
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