Hubble images of dying stars force cosmic reconsideration
December 17, 1997
Web posted at: 5:51 p.m. EST (2251 GMT)
WASHINGTON (CNN) -- New data gathered by NASA's Hubble Space
Telescope reveal that sun-like stars are dying in a much more
spectacular way than previously assumed, forcing scientists
to rethink their theories on the process.
The images also cast new light on the final moments of our
own sun, which is expected to die about 5 billion years from
now.
Astronomers on Wednesday revealed pictures showing
surprisingly intricate glowing patterns spun into space by
dying stars. The shapes are reminiscent of pinwheels, lawn
sprinkler-style jets, elegant goblet shapes, and rocket
engine exhausts.
The new pictures show the dying stars emitting nebulous
gasses in what scientists have dubbed a "final blaze of
glory" as a star expands before burning out and becoming what
is known as a white dwarf.
Scientists say that the new Hubble pictures completely
overturn the current assumption that sun-like stars
gracefully cast off a shell of glowing gas and then settle
into a long retirement as a burned-out white dwarf.
"The first time we looked at the Hubble's breathtaking
pictures, we knew that our older and simpler ideas of how
these objects are formed had to be overhauled," said Howard
Bond of the Space Telescope Science Institute.
Scientists point out that while the data are predominantly
about stars dying, they are also about cosmic rebirth, since
the heavier elements (like carbon) cooked in the stars are
ejected into interstellar space as raw material for
successive generations of stars, planets and, potentially,
life.
Among the surprising new details revealed by the Hubble
pictures:
- Unexplained disks and "donuts" of dust girdling a star,
which pinch outflowing gas.
- Remarkably sharp, inner bubbles of glowing gas blown out by
the violently outflowing gasses. This is called a "fast wind"
(1,000 miles/sec) ejected during the final stages of a star's
death.
- 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.
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This photo compares a ground-based image (L) taken
under optimum conditions with a new image from Hubble
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Bond said that these nebulae depicted in the new Hubble
pictures also give a preview of our own sun's fate: "Some 5
billion years from now, after the sun has become a red giant
and burned the Earth to cinder, it will eject its own
beautiful nebula and then fade away as a white dwarf star."