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"Long
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May 18, 2012
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Life might have formed as early as 10-12 billion years ago
May 18, 2012
Courtesy of the Niels Bohr Institute -
University of Copehhagen
and World
Science staff
“A long time ago in a galaxy far, far away” is the famous introductory line to the movie Star Wars, but it may be taking on a new real-life meaning. All objects in the image are distant galaxies –
not stars. Early galaxies from the infancy of the
universe more than 12 billion years ago evolved much more quickly than previously thought, new
research suggests. This could mean that already in the early history of the Universe, there was potential
for planet formation and life. (Image: Hubble Space
Telescope)
Physicists are reporting that conditions allowing life to form could have existed in some galaxies as early as 10 billion to 12 billion years ago—in the first quarter of the history of our universe.
The researchers drew the conclusions after studying galaxies that are so far away, those huge lengths of time are how long their light has taken to
reach us. “So we see the galaxies as they were then,” said physicist Johan
Fynbo at the University of Copenhagen, who worked on the research.
“For one of the galaxies,” he added, an analysis of the spectrum—or breakdown by color—of its light suggested
much of it is “enriched with a high content of heavier elements,” he went on. This creates “potential for planet formation and life.”
Earth-like planets can’t form with only the lightest elements, hydrogen and helium. But because accepted astronomical theories hold that it took some time for cosmic processes to generate heavier elements, this means that planet formation and life would face a corresponding delay in getting started.
That delay, however, may have been smaller than previously thought, if
Fynbo and colleagues are correct.
For several thousand years after the Big Bang—an explosion-like event
13.7 billion years ago that astronomers believe gave birth to the universe—everything was a hot, dense soup of gases and particles, scientists say. But the universe expanded, causing this soup to spread out and cool down. It remained thicker in some areas than others, though, and these parts, thanks to their own gravity, condensed instead of expanding. They ultimately became stars and galaxies.
The earliest of these probably consisted of primitive, giant stars made of only hydrogen and helium, according to astronomers. Heavier elements didn’t exist. These appeared later, created by nuclear processes in the stars. A star is a giant ball of gas that produces energy by combining hydrogen and helium into heavier and heavier elements, with some energy released each time. When this process can no longer go on, the star dies and flings huge clouds of dust and gas into space. The clouds are recycled into new stars, with a higher content of heavier elements.
As this process continues, generations of stars are born with progressively more heavy elements and metals. These elements, especially carbon and oxygen, are crucial for planets and life as we know it.
Until now, researchers thought that it took billions of years for stars to form and with that, galaxies with a high content of elements heavier than hydrogen and helium. But the new work indicates this process went surprisingly quickly in some galaxies.
“We have studied 10 galaxies in the early universe and analysed their light,” said
Fynbo. “Our expectation was that they would be relatively primitive and poor in heavier elements, but we discovered somewhat to our surprise that the gas in some of the galaxies and thus the stars in them had a very high content of heavier elements. The gas was just as enriched as our own Sun.”
The galaxies are so far away that they normally can’t be seen directly, but the researchers used a special method. “There are some extreme objects in the
universe called quasars. Quasars are gigantic black holes that are active and when matter falls into them, they emit light that is as strong as thousands of galaxies. They are like a kind of lighthouse that lights up in the
universe and can be seen very far away,” explained Jens-Kristian Krogager, a doctoral student at the university who participated in the research.
You can use a quasar as a light source if it’s behind a galaxy you want to observe, he went on. “We then look at the light from the quasar and can see that some light is missing. The missing quasar light in the image has been absorbed by the chemical elements in the galaxy in front of it,” he
said. The team’s findings were published online May 15 in the journal
Monthly Notices of the Royal Astronomical Society Letters.
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“A long time ago in a galaxy far, far away” is the famous introductory line to the movie Star Wars, but it may be taking on a new real-life meaning. Physicists are reporting that conditions allowing life to form could have existed in some galaxies as early as 10 billion to 12 billion years ago—in the first quarter of the history of our universe. The researchers drew the conclusions after studying galaxies that are so far away, those huge lengths of time are how long their light has taken to get there. “So we see the galaxies as they were then,” said physicist Johan Fynbo at the University of Copenhagen, who worked on the research. “For one of the galaxies,” he added, an analysis of the spectrum—or breakdown by color—of its light suggested “large parts of the galaxy are enriched with a high content of heavier elements,” he went on. This creates “potential for planet formation and life.” Earth-like planets can’t form with only the lightest elements, hydrogen and helium. But because accepted astronomical theories hold that it took some time for cosmic processes to generate heavier elements in any substantial quantities, this means that planet formation and life would face a corresponding delay in getting started. That delay, however, may have been smaller than previously thought, if Fynbo and colleagues are correct. For several thousand years after the Big Bang 13.7 billion years ago—an explosion-like event that astronomers believe gave birth to the universe—everything was a hot, dense soup of gases and particles, scientists say. But the universe expanded, causing this soup to spread out and cool down. It remained thicker in some areas than others, though, and these parts, thanks to their own gravity, condensed instead of expanding. They ultimately became stars and galaxies. The earliest of these probably consisted of primitive, giant stars made of only hydrogen and helium, according to astronomers. Heavier elements didn’t exist. These appeared later, created by nuclear processes in the stars. A star is a giant ball of glowing gas that produces energy by combining hydrogen and helium into heavier and heavier elements, with some energy released each time. When this process can no longer go on, the star dies and flings huge clouds of dust and gas into space. The clouds are condensed and recycled into new stars, with a higher content of heavier elements. As this process continues, generations of stars are born with progressively more heavy elements and metals. These elements, especially carbon and oxygen, are crucial for planets and life as we know it. Until now, researchers thought that it took billions of years for stars to form and with that, galaxies with a high content of elements heavier than hydrogen and helium. But the new work indicates this process went surprisingly quickly in some galaxies. “We have studied 10 galaxies in the early Universe and analysed their light,” said Fynbo. “Our expectation was that they would be relatively primitive and poor in heavier elements, but we discovered somewhat to our surprise that the gas in some of the galaxies and thus the stars in them had a very high content of heavier elements. The gas was just as enriched as our own Sun.” The galaxies are so far away that they normally can’t be seen directly, but the researchers used a special method. “There are some extreme objects in the Universe called quasars. Quasars are gigantic black holes that are active and when matter falls into them, they emit light that is as strong as thousands of galaxies. They are like a kind of lighthouse that lights up in the Universe and can be seen very far away,” explained Jens-Kristian Krogager, a doctoral student at the university who participated in the research. You can use a quasar as a light source if it’s behind a galaxy you want to observe, he went on. “We then look at the light from the quasar and can see that some light is missing. The missing quasar light in the image has been absorbed by the chemical elements in the galaxy in front of it,” he saod. The team’s findings were published online May 15 in the journal Monthly Notices of the Royal Astronomical Society Letters.