ATLANTA — In observations looking back to the edge of time, astronomers have captured images of the oldest and most distant galactic clusters ever seen, a discovery that shows immense numbers of stars formed less than 2 billion years after the birth of the cosmos.
The finding, to be presented this week at a meeting of the American Astronomical Society, suggests that the raw materials needed to create life may have formed far earlier than astronomers once believed, researchers say.
“We are coming to the realization that stars and galaxies formed very quickly after the Big Bang,” said Marc Postman, an astronomer at the Space Telescope Science Institute in Baltimore. “This means that galaxy and star formation was a rapid process. It was not something that took billions and billions of years to get under way.”
“Since it is true that stars formed very early after the Big Bang, then it is also true that life could have formed very early,” said John Blakeslee of Johns Hopkins University in Baltimore.
Other studies have established that the Big Bang, the birth of the cosmos, was about 13.7 billion years ago. For years, most astronomers believed that it took many billions of years for stars to form galaxies and then for those galaxies align themselves in vast structures called galactic clusters that could include thousands of galaxies.
The sun’s home galaxy, the Milky Way, is part of cluster that is, in turn, moving toward an even larger cluster of galaxies, each with hundreds of billions of stars like the sun.
“Our whole galaxy and its two dozen neighbors are falling into the Virgo cluster at a speed of about 300 kilometers a second (about 671,000 mph),” said Postman. “Now we have a good example of this sort of thing happening in very early time.”
Galaxies in ancient clusters
A series of studies by the Hubble Space Telescope focused on an area of the sky where radio telescopes had suggested the presence of very old galaxies. The Hubble detected mature, fully formed galaxies aligned in a vast cluster. Astronomers estimated that stars in the cluster formed more than 11 billion years ago.
Another observation detected a “proto-cluster,” a collection of young galaxies formed just 1.5 billion years after the Big Bang and just starting the process of forming a cluster. It is the most distant cluster ever seen. The galaxies were so young, the researchers found evidence of a burst of stars still being born.
“The stars in these galaxies are likely to be the second generation of stars,” said Postman.
Ingredients of life?
This suggests that even at an early moment in time, millions of stars already gone through their life cycle, forming, burning out, exploding and spewing into space the basic heavy elements, such as carbon and oxygen, needed for the formation of life.
“In these galaxies are all the basic building blocks for life,” said Postman. “Whether you can say that life follows a similar rapid time scale is a bit of a leap, but not a ridiculous one.”
With billions of stars in those early galaxies, a certain percentage may have planets “capable of sustaining life,” Postman suggested. “There is no proof, but it certainly is a possibility.”
The existence of the very early galactic clusters was supported by studies at the Chandra X-Ray Observatory and by observations by the European Southern Observatory. Postman and Blakeslee are co-authors, along with others, of reports last week in the journal Nature. Related studies were published in the Astrophysical Journal.
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