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Credit:
NASA, ESA,
William B. Latter (SIRTF Science Center/California Institute of Technology),
John H. Bieging (University of Arizona), Casey Meakin (University of Arizona),
A.G.G.M. Tielens (Kapteyn Astronomical Institute), Aditya Dayal (IPAC/NASA
Jet Propulsion Laboratory), Joseph L. Hora (Center for Astrophysics), and
Douglas M. Kelly (University of Arizona). |
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object shown in these NASA/ESA Hubble Space Telescope images is a remarkable
example of a star going through death throes just as it dramatically transforms
itself from a normal red giant star into a planetary nebula. This process
happens so quickly that such objects are quite rare, even though astronomers
believe that most stars like the Sun will eventually go through such a phase.
This star, with the prosaic name of OH231.8+4.2, is seen in these infrared
pictures blowing out gas and dust in two opposite directions. So much
dust has been cast off and now surrounds the star that it cannot be seen
directly, only its starlight that is reflected off the dust. The flow
of gas is very fast, with a velocity up to 450,000 mph (700,000 km/h).
With extreme clarity, these Hubble Near Infrared Camera and Multi-Object
Spectrometer (NICMOS) images reveal that the fast-moving gas and dust
are being collimated into several thin streamers (on the right) and a
jet-like structure (on the left), which can be seen extending away from
the centers of both pictures. On the right, wisps of material in jet-like
streamers appear to strike some dense blobs of gas. This interaction must
produce strong shock waves in the gas.
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The
pictures represent two views of the object. The color image is a composite
of four images taken with different NICMOS infrared filters on March 28,
1998. It shows that the physical properties of the material, both composition
and temperature, vary significantly throughout the outflowing material.
The black-and-white image was taken with one NICMOS infrared filter. That
image is able to show more clearly the faint detail and structure in the
nebula than can be achieved with the color composites.
Observations by radio astronomers have found many unusual molecules
in the gas around this star, including many containing sulfur, such as
hydrogen sulfide and sulfur dioxide. These sulfur compounds are believed
to be produced in the shock waves passing through the gas. Because of
the large amount of sulfur compounds, this object has earned the nickname
"The Rotten Egg" Nebula. It resides in the constellation Puppis.
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