Jurassic space: Ancient galaxies come together after billions of years
Feb 18, 2010 - 5:00:00 AM
|
|
|
The analysis was bolstered by infrared data from NASA's Spitzer Space Telescope and ultraviolet observations from the Galaxy Evolution Explorer (GALEX) and NASA's Swift satellite. Those data helped the astronomers measure the total amount of star formation in the system. Hubble has the sharpness to resolve individual star clusters, which allowed us to age-date the clusters, Gallagher adds.
|
By University of Western Ontario,
[RxPG] Imagine finding a living dinosaur in your backyard. Astronomers have found the astronomical equivalent of prehistoric life in our intergalactic backyard: a group of small, ancient galaxies that has waited 10 billion years to come together. These late bloomers are on their way to building a large elliptical galaxy.
Such encounters between dwarf galaxies are normally seen billions of light-years away and therefore occurred billions of years ago. But these galaxies, members of Hickson Compact Group 31, are relatively nearby, only 166 million light-years away.
New images of this foursome by NASA's Hubble Space Telescope offer a window into the universe's formative years when the buildup of large galaxies from smaller building blocks was common.
Astronomers have known for decades that these dwarf galaxies are gravitationally tugging on each other. Their classical spiral shapes have been stretched like taffy, pulling out long streamers of gas and dust. The brightest object in the Hubble image is actually two colliding galaxies. The entire system is aglow with a firestorm of star birth, triggered when hydrogen gas is compressed by the close encounters between the galaxies, and collapses to form stars.
The Hubble observations have added important clues to the story of this interacting group, allowing astronomers to determine when the encounter began and to predict a future merger.
We found the oldest stars in a few ancient globular star clusters that date back to about 10 billion years ago. Therefore, we know the system has been around for a while, says astronomer Sarah Gallagher of The University of Western Ontario in London, Ontario, leader of the Hubble study. Most other dwarf galaxies like these interacted billions of years ago, but these galaxies are just coming together for the first time. This encounter has been going on for at most a few hundred million years, the blink of an eye in cosmic history. It is an extremely rare local example of what we think was a quite common event in the distant universe.
Everywhere the astronomers looked in this group they found batches of infant star clusters and regions brimming with star birth. The entire system is rich in hydrogen gas, the stuff of which stars are made. Gallagher and her team used Hubble's Advanced Camera for Surveys to resolve the youngest and brightest of those clusters, which allowed them to calculate the clusters' ages, trace the star-formation history, and determine that the galaxies are undergoing the final stages of galaxy assembly.
The analysis was bolstered by infrared data from NASA's Spitzer Space Telescope and ultraviolet observations from the Galaxy Evolution Explorer (GALEX) and NASA's Swift satellite. Those data helped the astronomers measure the total amount of star formation in the system. Hubble has the sharpness to resolve individual star clusters, which allowed us to age-date the clusters, Gallagher adds.
Advertise in this space for $10 per month.
Contact us today.
|
 |
|
Subscribe to Latest Research Newsletter
|
|
|
|
Feedback
|
For any corrections of factual information, to contact the editors or to send
any medical news or health news press releases, use
feedback form
|
Top of Page
|
