Spitzer Spies Parallelogram-Shaped Galactic Meal

[photo: This image taken by NASA's Spitzer Space Telescope shows in unprecedented detail the galaxy Centaurus A's last big meal: a spiral galaxy seemingly twisted into a parallelogram-shaped structure of dust. Spitzer's ability to see dust and also see through it allowed the telescope to peer into the center of Centaurus A and capture this galactic remnant as never before.An elliptical galaxy located 10 million light-years from Earth, Centaurus A is one of the brightest sources of radio waves in the sky. These radio waves indicate the presence of a supermassive black hole, which may be "feeding" off the leftover galactic meal.A high-speed jet of gas can be seen shooting above the plane of the galaxy (the faint, fuzzy feature pointing from the center toward the upper left). Jets are a common feature of galaxies, and this one is probably receiving an extra boost from the galactic remnant.Scientists have created a model that explains how such a strangely geometric structure could arise. In this model, a spiral galaxy falls into an elliptical galaxy, becoming warped and twisted in the process. The folds in the warped disc create the parallelogram-shaped illusion.]

Release: June 1, 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.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 11 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.



[photo: This image taken by NASA's Spitzer Space Telescope shows in unprecedented detail the galaxy Centaurus A's last big meal: a spiral galaxy seemingly twisted into a parallelogram-shaped structure of dust. An elliptical galaxy located 10 million light-years from Earth, Centaurus A is one of the brightest sources of radio waves in the sky. These radio waves indicate the presence of a supermassive black hole, which may be "feeding" off the leftover galactic meal.This spectacular image combines 5.8 micron and 8.0 micron data obtained by an infrared array camera aboard Spitzer. These wavelengths emphasize the emission from dust rather than the light produced by stars in the galaxy. The resulting image shows with greater clarity the strange parallelogram-shaped feature embedded near the center of the galaxy. Scientists have created a model that explains how such a strangely geometric structure could arise. In this model, a spiral galaxy falls into an elliptical galaxy, becoming warped and twisted in the process. The folds in the warped disc create the parallelogram-shaped illusion. ]

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.