When they are viewed by the best earthbound telescopes, the entwined Antennae galaxies (left) do not look like much more than two joined blobs trailing curious spirals of light. But when the orbiting Hubble Space Telescope pointed its Wide Field Planetary Camera 2 at the pale center of the colliding galaxies (inset), an astonishingly beautiful--and surprising--picture emerged.
The Hubble's vastly superior resolving power enabled it to peer into the inferno ignited by the collision of the two galaxies. The image below is a composite of four snapshots taken by Hubble astronomers on January 20, 1996. Detailed examination reveals more than 1,000 bright, young star clusters bursting in a brief, intense celestial "fireworks show." "The sheer number of these young star clusters is amazing," says Brad Whitmore, who headed the team that made the images at the Space Telescope Science Institute.
The cores of the twin galaxies, designated NGC 4038 and NGC 4039, appear as two orange blobs, crisscrossed by filaments of dark dust. A wide band of turbulent dust, called the overlap region, spans the space between the cores of the two galaxies. The sweeping spirals, traced by bright blue star clusters, are the result of a firestorm of star birth triggered by the collision.
(To zoom in, click on insets)
The Hubble astronomers did not stop with the creation of this composite. They zoomed in on even smaller areas to pinpoint the key stages of star formation (insets). The two larger, orange areas are close-ups of clouds of interstellar dust and hydrogen gas that are being funneled into the center of the galaxy, where enormous forces cause them to coalesce into new stars. The two bright blue areas are regions filled with newly formed "globular clusters," the nurseries of celestial infants.