February 14, 2012
Cluster Of Stars Survived Massacre 13 Billion Years Ago
Astronomers have found a cluster of stars that they say survived a massacre 13 billion years ago.
The team used computer simulations to look at how the compact groups of stars surrounding our Milky Way galaxy were formed.
There are about 200 compact groups sitting close to our galaxy, each containing up to a million stars.
The researchers ran simulations of isolated and colliding galaxies, in which they included a model for formation and destruction of stellar clusters.
Once a galaxy collides, they often generate bursts of star formations and a wealth of young stellar clusters of many different sizes.
However, the team found that while the very brightest and largest clusters were capable of surviving the galaxy collision, the numerous smaller clusters were effectively destroyed by the rapidly changing gravitational forces that occur during these starbursts.
According to the team, the wave of stardust came to an end after about 2 billion years, and only clusters with high numbers of stars survived.
These clusters had all the characteristics of a young population of global clusters as they would have looked 11 billion years ago.
"It is ironic to see that starbursts may produce many young stellar clusters, but at the same time also destroy the majority of them," Dr Diederik Kruijssen of the Max Planck Institute for Astrophysics in Garching, Germany said in a press release.
"This occurs not only in galaxy collisions, but should be expected in any starburst environment."
He said in the early Universe, it makes perfect sense that all globular clusters have about the same large number of stars. He said their smaller brothers and sisters that did not contain as many stars were destroyed.
The team found that most of the star clusters were destroyed shortly after their formation, when the galactic environment was still very hostile to the young clusters.
"In the nearby Universe, there are several examples of galaxies that have recently undergone large bursts of star formation," Kruijssen said in the press release. "It should therefore be possible to see the rapid destruction of small stellar clusters in action.
"If this is indeed found by new observations, it will confirm our theory for the origin of globular clusters."
He said he believes because global clusters are comparable everywhere, they can be used as fossils to help shed more light on the conditions in which the first stars and galaxies were born.
The research is published in the journal Monthly Notices of the Royal Astronomical Society.
Image Caption: This image of the Antennae galaxies shows a multitude of bright young star clusters, groups of stars associated with regions of intense star formation. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration
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