Contact: Michele Kaufman Rallis, (614) 292-4464
Written by Pam Frost, (614) 292-9475
[email protected]
HUBBLE HERITAGE PROJECT SHOWCASES STUNNING PHOTO OF GALAXIES
COLUMBUS, Ohio -- More than 100 million light years from earth, two galaxies brush against each other, locked in an eternal dance -- and an Ohio State University physicist and her colleagues have captured the moment.
The striking photo will be showcased through the rest of November 1999 on the World Wide Web site of the Hubble Heritage Project: http://heritage.stsci.edu
Starting December 1, 1999, the photo will be available on the site's archive page (look for NGC2207 & IC2163):
http://heritage.stsci.edu/public/gallery/galindex.html#archive
The Web site provides the public with pictorially stunning images of astronomical objects obtained with the Hubble Space Telescope, and is maintained by the Space Telescope Science Institute, located in Baltimore, MD.
Michele Kaufman Rallis, a scientist in Ohio State's departments of physics and astronomy, explained that the galaxy IC 2163 (on the right) exhibits an unusual eye-shaped structure, depicted in the photo. Fast-moving gas and streams of stars trail along the "eyelids," and two long arms of stars, gas and dust extend outward.
"These features are indicative of a very recent and close encounter with its spiral galaxy companion, NGC 2207," she said.
In 1995, Kaufman Rallis and her collaborators published a detailed study of this galaxy pair based on their observations from ground-based telescopes. The galaxies' distorted shapes indicated that the two had collided and that their mutual gravity created tidal forces that pulled gas, dust, and stars from the galaxies. The researchers simulated the movement on computer, and confirmed that the galaxies' outer regions had grazed against each other; at closest approach, the center of IC 2163 had passed within 100,000 light years of the center of NGC 2207.
In 1996 and 1998, the researchers were able to photograph the pair in more detail with the Hubble Space Telescope, and the resulting image is the one the Hubble Heritage Project has chosen to display.
"The high resolution of the Hubble Space Telescope image revealed an impressive array of parallel dust filaments extending like fine brush strokes on the side of IC 2163 opposite its companion," Kaufman Rallis said. "These are probably shock fronts in the region where the streaming gas meets the tidal arm."
"Furthermore, the silhouetting of a spiral arm of NGC 2207 against IC 2163 in the background provides an unprecedented view of the structure of dust filaments and star formation in a spiral arm," Kaufman Rallis noted.
According to the researchers' computer model, the closest approach between these galaxies occurred 40 million years ago -- about the time the first modern mammals appeared on the earth, but relatively recent by astronomical standards.
The researchers calculated that IC 2163 doesn't possess enough energy to escape the gravity of the larger NGC 2207. They predict it will swing around in its orbit and graze against its partner again in the distant future.
For this work, Kaufman Rallis collaborated with Bruce Elmegreen, a research scientist at IBM's T.J. Watson Research Center; Debra Meloy Elmegreen, professor of astronomy at Vassar College; Elias Brinks, professor of astronomy at Universidad de Guanajuato, Mexico; Curt Struck, professor of astrophysics at Iowa State University; Magnus Thomasson, an astronomer at Onsala Space Observatory, Sweden; Maria Sundin, a lecturer and researcher at Gˆteborg University, also in Sweden; and Mario Klaric, who teaches astronomy and physics in Columbia, SC.
People who visit the Web site may click on the image to learn more about the galaxies and the researchers involved.
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