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A Whirlpool 'Warhol' from NASA's Spitzer Telescope Unlike Andy
Warhol's famous silkscreen grids of repeating images rendered in different colors,
the varying hues of this galaxy represent how its appearance changes in
different wavelengths of light - from visible light to the infrared light seen
by NASA's Spitzer Space Telescope.
The Whirlpool
galaxy, also known as Messier 51 and NGC 5194/5195, is actually a pair of
galaxies that are tugging and
distorting each other through their mutual gravitational attraction.
Located approximately 23 million light-years away, it resides in the
constellation Canes Venatici.
The leftmost
panel (a) shows the Whirlpool in visible light, much as our eye might see it
through a powerful telescope. In fact, this image comes from the Kitt Peak
National Observatory 2.1-meter (6.8-foot) telescope. The spiraling arms are
laced with dark threads of dust that radiate little visible light and obscure
stars positioned within or behind them.
The second
panel from the left (b) includes two visible-light wavelengths (in blue and
green) from Kitt Peak but adds Spitzer's infrared data in red. This emphasizes
how the dark dust veins that block our view in visible light begin to light up
at these longer, infrared wavelengths.
Spitzer's
full infrared view can be seen in the right two panels, which cover slightly
different ranges of infrared light.
In the middle-right
panel (c), we see three wavelengths of infrared light: 3.6 microns (shown in
blue), 4.5 microns (green) and 8 microns (red). The blended light from the
billions of stars in the Whirlpool is brightest at the shorter infrared
wavelengths and is seen here as a blue haze. The individual blue dots across
the image are mostly nearby stars and a few distant galaxies. Red features show
us dust composed mostly of carbon that is lit up by the stars in the galaxy.
This glowing
dust helps astronomers see where the densest areas of gas pile up in the spaces
between the stars. Dense gas clouds are difficult to see in visible or infrared
light, but they will always be present where there is dust.
The far-right
panel (d) expands our infrared view to include light at a wavelength of 24
microns (in red), which is particularly good for highlighting areas where the
dust is especially hot. The bright reddish-white spots trace regions where new
stars are forming and, in the process, heating their surroundings.
The infrared
views of the Whirlpool galaxy also show how dramatically different its two
component parts are: The smaller companion galaxy at the top of the image has
been stripped nearly clean of dust features that stand out so brilliantly in
the lower spiral galaxy. The faint bluish haze seen around the upper galaxy is
likely the blended light from stars thrown out of the galaxies as these two
objects pull at each other during their close approach.
The Kitt Peak
visible-light image (a) shows light at 0.4 and 0.7 microns (blue and red). The
rightmost two images (c and d) are from Spitzer with red, green and blue
corresponding to wavelengths of 3.6, 4.5 and 8.0 microns (middle right) and
3.6, 8.0 and 24 microns (far right). The middle-left (b) image blends visible
wavelengths (blue/green) and infrared (yellow/red). All of the data shown here
were released as part of the Spitzer Infrared Nearby Galaxies Survey (SINGS)
project, captured during Spitzer's cryogenic
and warm missions.
The Jet Propulsion Laboratory in Pasadena, California, manages
the Spitzer Space Telescope mission for NASA's Science Mission Directorate in
Washington. Science operations are conducted at the Spitzer Science Center at
Caltech in Pasadena. Space operations are based at Lockheed Martin Space
Systems in Littleton, Colorado. Data are archived at the Infrared Science
Archive housed at IPAC at Caltech. Caltech manages JPL for NASA.
For more information on
Spitzer, visit:
www.nasa.gov/spitzer and www.spitzer.caltech.edu/
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