Spitzer Spies Parallelogram-Shaped Galactic Meal
A Spitzer image showing galaxy Centaurus A's last big meal: a spiral galaxy twisted into a parallelogram-shaped structure of dust.
June 01, 2004
Peering into the "gut" of the galaxy Centaurus A, NASA's
Spitzer Space Telescope has captured in unprecedented detail
this massive galaxy's last big meal: a spiral galaxy twisted
into a parallelogram-shaped structure of dust.
The findings were presented today at the American
Astronomical Society annual meeting in Denver, Colo. A
stunning image of the galaxy and its bizarre dust structure
can be found at
http://www.spitzer.caltech.edu/Media/releases/ssc2004-09/index.shtml.
While previous observations with other telescopes have
revealed this galactic remnant, it appeared as one long and
irregular bar of dust. Spitzer's uniquely sensitive infrared
eyes allowed the telescope to see clearly this strangely
geometric structure for the first time.
"Now we can actually see the shape of this structure, which
helps us explain how it arose," said Dr. Jocelyn Keene,
principal investigator for the new research and an
astronomer at NASA's Jet Propulsion Laboratory and the
California Institute of Technology, both in Pasadena, Calif.
Located 10 million light-years away, Centaurus A is a type
of galaxy known as "elliptical." It is one of the brightest
sources of radio waves in the sky, which suggests the
presence of a supermassive black hole at its center. About
200 million years ago, this galaxy is believed to have
consumed a smaller spiral galaxy - the contents of which
appear to be churning inside Centaurus A's core, triggering
new generations of star birth.
Resolving this unusual parallelogram structure has helped
astronomers finally put together a picture of its history.
The geometric shape can be explained using a model that
describes a flat spiral galaxy falling into an elliptical
galaxy and becoming twisted and warped in the process. The
folds in the warped disc, when viewed nearly edge on, take
on the appearance of a parallelogram. The model predicts
that the leftover galaxy will ultimately flatten into a
plane before being entirely devoured by Centaurus A. Warped
discs like this are the "smoking guns" of galactic
cannibalism, providing proof that one galaxy once made a
meal of another.
Such galactic feeding has long thought to be a mechanism by
which giant elliptical galaxies form and grow, and likely
provides the fuel that drives the strong radio activity
surrounding Centaurus A's central black hole.
Other authors of this research include Dr. Alice Quillen of
the University of Rochester, N.Y., and Drs. Daniel Stern,
Varoujan Gorjian, Karl Stapelfeldt, Charles Lawrence, Peter
Eisenhardt and Michael Werner of JPL.
For more information about the Spitzer Space Telescope,
visit www.spitzer.caltech.edu.
Launched on August 25, 2003, from Cape Canaveral, Fla., the
Spitzer Space Telescope is the fourth of NASA's Great
Observatories. This program includes the Hubble Space
Telescope, Chandra X-ray Observatory and Compton Gamma Ray
Observatory. JPL manages the Spitzer Space Telescope mission
for NASA's Office of Space Science, Washington. Science
operations are conducted at the Spitzer Science Center. The
California Institute of Technology manages JPL.
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