An aging star’s last hurrah is creating a flurry of glowing knots
of gas that appear to be streaking through space in this close-up
image of the Dumbbell Nebula, taken with NASA’s Hubble Space
Telescope.

The Dumbbell, a nearby planetary nebula residing more than
1,200 light-years away, is the result of an old star that has
shed its outer layers in a glowing display of color. The nebula,
also known as Messier 27 (M27), was the first planetary nebula
ever discovered. French astronomer Charles Messier spotted it
in 1764.

The Hubble images of the Dumbbell show many knots, but their
shapes vary. Some look like fingers pointing at the central
star, located just off the upper left of the image; others are
isolated clouds, with or without tails. Their sizes typically
range from 11 – 35 billion miles (17 – 56 billion kilometers),
which is several times larger than the distance from the Sun
to Pluto. Each contains as much mass as three Earths.

The knots are forming at the interface between the hot (ionized)
and cool (neutral) portion of the nebula. This area of temperature
differentiation moves outward from the central star as the nebula
evolves. In the Dumbbell astronomers are seeing the knots soon
after this hot gas passed by.

Dense knots of gas and dust seem to be a natural part of the
evolution of planetary nebulae. They form in the early stages, and
their shape changes as the nebula expands. Similar knots have been
discovered in other nearby planetary nebulae that are all part of
the same evolutionary scheme. They can be seen in Hubble telescope
photos of the Ring Nebula (NGC 6720), the Eskimo Nebula (NGC
2392) and the Retina Nebula (IC 4406). The detection of these
knots in all the nearby planetaries imaged by the Hubble telescope
allows astronomers to hypothesize that knots may be a feature
common in all planetary nebulae.

This image, created by the Hubble Heritage Team (STScI), was
taken by Hubble’s Wide Field Planetary Camera 2 in November
2001, by Bob O’Dell (Vanderbilt University) and collaborators.
The filters used to create this color image show oxygen in blue,
hydrogen in green and a combination of sulfur and nitrogen
emission in red.

Image Credit: NASA and the Hubble Heritage Team (STScI/AURA)
Acknowledgment: C.R. O’Dell (Vanderbilt University)

NOTE TO EDITORS: For additional information, please contact
Dr. C.R. (Bob) O’Dell, Vanderbilt University, Phys. and Ast. Dept.,
Box 1807 Station B, Nashville, TN 37235, (phone) 615-343-1779,
(fax) 615-343-7263, (e-mail) cr.odell@vanderbilt.edu or

Dr. Keith Noll, Hubble Heritage Team, Space Telescope Science
Institute, 3700 San Martin Drive, Baltimore, MD 21218, (phone)
410-338-1828, (fax) 410-338-4579, (e-mail) noll@stsci.edu.

Electronic image files and additional information are available at
http://hubblesite.org/news/2003/06 and
http://heritage.stsci.edu/2003/06.

The Space Telescope Science Institute (STScI) is operated by the
Association of Universities for Research in Astronomy, Inc. (AURA),
for NASA, under contract with the Goddard Space Flight Center,
Greenbelt, MD. The Hubble Space Telescope is a project of international
cooperation between NASA and the European Space Agency (ESA).