October 19, 1999
Photo No: H99-39
The "Rotten Egg" Nebula - A Planetary Nebula in the Making
The object shown in this NASA/ESA Hubble Space Telescope image 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 this
infrared picture 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 .
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 center. 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.
This 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
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
These NICMOS data pose a serious challenge to astrophysical theorists:
How can a star generate such tightly collimated streams of gas and dust
and accelerate them to such very high velocities? William B. Latter from
the California Institute of Technology and his group are using these
data to obtain a better understanding of the detailed structure in the
outflowing material, look for evidence for the origin of the thin
streamers and jets, and learn more about the star itself. This
information will give astronomers a more complete understanding of the
final stages in the lives of stars like our Sun.
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).