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| Visible-light/Infrared Composite | Visible-light Image |
This infrared image from NASA's Spitzer Space Telescope shows a galaxy
that appears to be sizzling hot, with huge plumes of smoke swirling around
it. The galaxy, known as Messier 82 or the "Cigar galaxy," is in fact,
smothered in smoky dust particles (red) blown out into space by the
galaxy's hot stars (blue).
The visible-light picture of Messier 82, shows only a bar of light against
a dark patch of space. Longer exposures of the galaxy (not pictured here)
have revealed cone-shaped clouds of hot gas above and below the galaxy's
plane. It took Spitzer's three sensitive instruments to show that the
galaxy is also surrounded by a huge, hidden halo of smoky dust (red in
infrared image).
Of those instruments, Spitzer's infrared spectrograph told astronomers
that the dust contains a carbon-containing compound, called polycyclic
aromatic hydrocarbon. This smoky molecule can be found on Earth in
tailpipes, barbecue pits and other places where combustion reactions have
occurred.
The image composite compares a visible-light view (left) of the
"Cigar galaxy" to an infrared view from NASA's Spitzer Space Telescope of
the same galaxy. The movie "Cigar Galaxy up in Smoke" begins with the visible image of the galaxy
looking cool as a cucumber, then fades into the infrared image, revealing
a smokin' hot "cigar."
Messier 82 is located about 12 million light-years away in the Ursa Major
constellation. It is viewed from its side, or edge on, so it appears as a
thin cigar-shaped bar. The galaxy is termed a starburst because its
shrouded core is a fiery hotbed of stellar birth. A larger nearby galaxy,
called Messier 81, is gravitationally interacting with Messier 82,
prodding it into producing the new stars.
This picture was taken by Spitzer's infrared array camera as a part of
the Spitzer Infrared Nearby Galaxy Survey. Blue indicates infrared light
of 3.6 microns, green corresponds to 4.5 microns, and red to 5.8 and 8.0
microns. The contribution from starlight (measured at 3.6 microns) has
been subtracted from the 5.8- and 8-micron images to enhance the
visibility of the dust features.
The visible-light picture is from the National Optical Astronomy
Observatory, Tucson, Ariz.
Note: The size of the Full-Res TIFF for the still image is 1484 samples x 1484 lines.
