Image credit: NASA-ESA/STScI/AURA/JPL-Caltech
This image of distant interacting galaxies, known
collectively as Arp 142, bears an uncanny resemblance to a penguin
guarding an egg. Data from NASA's Spitzer and Hubble space telescopes
have been combined to show these dramatic galaxies in light that spans
the visible and infrared parts of the spectrum.
This dramatic pairing shows two galaxies that couldn't look more
different as their mutual gravitational attraction slowly drags them
closer together.
The "penguin" part of the pair, NGC 2336, was probably once a
relatively normal-looking spiral galaxy, flattened like a pancake with
smoothly symmetric spiral arms. Rich with newly-formed hot stars, seen
in visible light from Hubble as bluish filaments, its shape has now been
twisted and distorted as it responds to the gravitational tugs of its
neighbor. Strands of gas mixed with dust stand out as red filaments
detected at longer wavelengths of infrared light seen by Spitzer.
The "egg" of the pair, NGC 2937, by contrast, is nearly featureless.
The distinctly different greenish glow of starlight tells the story of a
population of much older stars. The absence of glowing red dust
features informs us that it has long since lost its reservoir of gas and
dust from which new stars can form. While this galaxy is certainly
reacting to the presence of its neighbor, its smooth distribution of
stars obscures any obvious distortions of its shape.
Eventually these two galaxies will merge to form a single object,
with their two populations of stars, gas and dust intermingling. This
kind of merger was likely a significant step in the history of most
large galaxies we see around us in the nearby universe, including our
own Milky Way.
At a distance of about 23 million light-years, these two galaxies are
roughly 10 times farther away than our nearest major galactic neighbor,
the Andromeda galaxy. The blue streak at the top of the image is an
unrelated background galaxy that is farther away than Arp 142.
Combining light from across the visible and infrared spectrums helps
astronomers piece together the complex story of the life cycles of
galaxies. While this image required data from both the Spitzer and
Hubble telescopes to cover this range of light, NASA's upcoming James
Webb Space Telescope will be able to see all of these wavelengths of
light, and with dramatically better clarity.
The Hubble Space Telescope is a project of international cooperation
between NASA and ESA (European Space Agency). NASA's Goddard Space
Flight Center in Greenbelt, Maryland, manages the telescope. The Space
Telescope Science Institute (STScI) in Baltimore, Maryland, conducts
Hubble science operations. STScI is operated for NASA by the Association
of Universities for Research in Astronomy, Inc., in Washington, D.C.
NASA's Jet Propulsion Laboratory, Pasadena, California, manages the
Spitzer Space Telescope mission for NASA's Science Mission Directorate,
Washington. Science operations are conducted at the Spitzer Science
Center at Caltech in Pasadena, California. Spacecraft operations are
based at Lockheed Martin Space Systems Company, Littleton, Colorado.
Data are archived at the Infrared Science Archive housed at the Infrared
Processing and Analysis Center at Caltech. Caltech manages JPL for
NASA.
Editor: Tony Greicius
Source: NASA/Spitzer Telescope
