Curt Struck, Physics and Astronomy, (515) 294-3666
Skip Derra, News Service, (515) 294-4917


AMES, Iowa -- An "owlish" image of two galaxies grazing by each other in a cosmic dance fueled by gravitational pull is a featured image this month of the Space Telescope Institute, operator of NASA's Hubble Space Telescope. Curt Struck, an Iowa State physics and astronomy professor, is a member of the team that used the Hubble telescope to take images of the two galaxies, designated NGC 2207 and IC 2163.

"This really is quite gorgeous," said Struck. "The system contains an ocular, or eyelid shaped, galaxy. But the two of them are so close together it looks like two big eyes of an owl surrounded by feathers."

The image is part of the Space Telescope Institute's Heritage project, which has the goal of constructing striking images that act as a bridge between scientists and the public. The images that make up the overall picture of NGC 2207 and IC 2163 were taken in 1996 and 1998, but the overall image is first being released to the public today (Nov. 4).

The Hubble Space Telescope is an orbiting telescope that is free of the distortion caused by Earth's atmosphere. It has returned many spectacular images of stars, galaxies, celestial explosions and colliding galaxies that are not obtainable from Earth based telescopes. The image of NGC 2207 and IC 2163 helps provide insights into the structure and evolution of galaxies, Struck said.

"Part of one galaxy is back lit by the second galaxy," Struck explained. "There are only a few cases where you can study the features of a galaxy that are back lit in this way. It allows us to see star dust, material that eventually could evolve into stars sometime down the road."

Struck said that NGC 2207 and IC 2163 are a relatively nearby colliding galaxy pair, roughly 114 million light years from Earth in the constellation of Canis Major. (A light year is the distance light travels in a year, about 6 trillion miles).

Astronomers believe that colliding galaxies are areas where extremely high rates of star birth and formation take place. But these two galaxies had collided only recently, some 40 million years ago.

"Because it is so recent, the star formation hasn't turned on yet," Struck said.

Dust lanes are clearly visible in the image in the spiral arms of NGC 2207 as it is silhouetted against IC 2163. The image also shows the larger NGC 2207 distorting the smaller IC 2163 galaxy. It is expected that these two galaxies will continue their galactic dance, trapped in a mutual orbit around each other and eventually merge into a single, more massive galaxy several billion years from now.

"We believe that by studying these colliding galaxies we can learn more about how the process of induced star formation works," Struck explained. "We believe that this process may be responsible for a large fraction of all the stars ever formed in our universe."

Struck is part of an eight-person team working to understand the mechanics and inner workings of colliding galaxies. Part of their work was to use the Hubble Space Telescope to observe such galaxies. The team will present their findings at the American Astronomical Society meeting in January 2000.

Access to the image is at http://heritage.stsci.edu.

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