Image: Primordial gas
Ceverino, Dekel and Primack
An artist's conception shows gas around a forming galaxy in a large computer simulation. The pristine gas detected by astronomers could lie in one of the filamentary regions.
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updated 11/10/2011 2:00:02 PM ET 2011-11-10T19:00:02

After decades of scouring the universe, astronomers finally have found two immense clouds of gas that are pristine — free of the metals fired out into the cosmos by stars.

The findings, published Thursday on the journal Science's website, provide the first solid detection of primitive, uncontaminated gas and support the longstanding theory as to how the chemical elements were formed in the early universe. It is these types of pure gas clouds that formed the first stars.

The research also suggests that stars have not succeeded at distributing metals throughout the entire cosmos; astronomers consider metals to be heavier elements like carbon, silicon, iron, even oxygen.

A separate study, also published by Science, concludes that the early stars were much smaller than thought — tens of times bigger than our sun, versus hundreds of times bigger.

"There's kind of been this missing link in this picture of how elements form. We haven't been able to detect what we expect to be out there, which is otherwise primordial material, stuff that would be metal-free," said co-author J. Xavier Prochaska, an astronomer at the University of California at Santa Cruz.

"This is the first solid detection of such gas," he said in a phone interview. "It's something we expected to find at some level, but it has been challenging to find it."

The two pristine gas clouds were formed 2 billion years after the big bang that gave rise to the universe.

Prochaska, along with lead author Michele Fumagalli, a graduate student at Santa Cruz, and John O'Meara, an astronomer at Saint Michael's College in Colchester, Vt., discovered the two clouds by analyzing light from quasars. They used the Keck Observatory in Hawaii.

Nothing heavier than hydrogen and its heavier isotope deuterium was found, in any sizable amount, in the two clouds. The researchers did not have the means to detect helium, but suspect it's there in abundance. The virtual absence of heavier elements or so-called metals — which they did have the ability to see — confirms the clouds are pristine, they said.

Many more are out there "for sure," Prochaska noted. These two particular clouds are not dense enough to become stars — yet. They would have to fall into a galaxy and transform into a cloud of molecular hydrogen, before giving birth to new stars.

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The researchers identified 50 potential candidates, of which just these two clouds were essentially metal-free.

"We've just started," Prochaska said. "I expect even today, in our current universe, there should be regions that are completely unpolluted" because of the vast expanse of so-called empty space between galaxies, he added.

"Galaxies and stars really don't fill up much of the volume of the universe. We're rare," he said. "Our Milky Way is an island, if you will, in the vast expanse of the universe, so there's plenty of volume in the universe which is far, far away from galaxies."

The study that concluded the first stars were not nearly as big as envisioned was conducted by a Japanese-U.S. team led by Takashi Hosokawa of NASA's Jet Propulsion Laboratory in Pasadena, Calif., and Kyoto University.

University of Texas astronomer Volker Bromm, who was not involved in either study, said the separate results may well tie together.

The smaller the early stars, the smaller the explosions, Bromm noted, and the less capability for dispersing heavy elements — that is, metals — into the universe via end-of-life stellar explosions, or supernovas.

His own team at Austin reached similar findings, recently, on the diminished size of early stars.

"Ten times the solar mass. Still, by all standards, very massive," Bromm said, "but a little less massive" than initially thought.

Copyright 2011 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Photos: Month in Space: January 2014

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  1. Southern stargazing

    Stars, galaxies and nebulas dot the skies over the European Southern Observatory's La Silla Paranal Observatory in Chile, in a picture released on Jan. 7. This image also shows three of the four movable units that feed light into the Very Large Telescope Interferometer, the world's most advanced optical instrument. Combining to form one larger telescope, they are greater than the sum of their parts: They reveal details that would otherwise be visible only through a telescope as large as the distance between them. (Y. Beletsky / ESO) Back to slideshow navigation
  2. A balloon's view

    Cameras captured the Grandville High School RoboDawgs' balloon floating through Earth's upper atmosphere during its ascent on Dec. 28, 2013. The Grandville RoboDawgs’ first winter balloon launch reached an estimated altitude of 130,000 feet, or about 25 miles, according to coaches Mike Evele and Doug Hepfer. It skyrocketed past the team’s previous 100,000-feet record set in June. The RoboDawgs started with just one robotics team in 1998, but they've grown to support more than 30 teams at public schools in Grandville, Mich. (Kyle Moroney / AP) Back to slideshow navigation
  3. Spacemen at work

    Russian cosmonauts Oleg Kotov, right, and Sergey Ryazanskiy perform maintenance on the International Space Station on Jan. 27. During the six-hour, eight-minute spacewalk, Kotov and Ryazanskiy completed the installation of a pair of high-fidelity cameras that experienced connectivity issues during a Dec. 27 spacewalk. The cosmonauts also retrieved scientific gear outside the station's Russian segment. (NASA) Back to slideshow navigation
  4. Special delivery

    The International Space Station's Canadian-built robotic arm moves toward Orbital Sciences Corp.'s Cygnus autonomous cargo craft as it approaches the station for a Jan. 12 delivery. The mountains below are the southwestern Alps. (NASA) Back to slideshow navigation
  5. Accidental art

    A piece of art? A time-lapse photo? A flickering light show? At first glance, this image looks nothing like the images we're used to seeing from the Hubble Space Telescope. But it's a genuine Hubble frame that was released on Jan. 27. Hubble's team suspects that the telescope's Fine Guidance System locked onto a bad guide star, potentially a double star or binary. This caused an error in the tracking system, resulting in a remarkable picture of brightly colored stellar streaks. The prominent red streaks are from stars in the globular cluster NGC 288. (NASA / ESA) Back to slideshow navigation
  6. Supersonic test flight

    A camera looking back over Virgin Galactic's SpaceShipTwo's fuselage shows the rocket burn with a Mojave Desert vista in the background during a test flight of the rocket plane on Jan. 10. Cameras were mounted on the exterior of SpaceShipTwo as well as its carrier airplane, WhiteKnightTwo, to monitor the rocket engine's performance. The test was aimed at setting the stage for honest-to-goodness flights into outer space later this year, and eventual commercial space tours.

    More about SpaceShipTwo on PhotoBlog (Virgin Galactic) Back to slideshow navigation
  7. Red lagoon

    The VLT Survey Telescope at the European Southern Observatory's Paranal Observatory in Chile captured this richly detailed new image of the Lagoon Nebula, released on Jan. 22. This giant cloud of gas and dust is creating intensely bright young stars, and is home to young stellar clusters. This image is a tiny part of just one of 11 public surveys of the sky now in progress using ESO telescopes. (ESO/VPHAS team) Back to slideshow navigation
  8. Fire on the mountain

    This image provided by NASA shows a satellite view of smoke from the Colby Fire, taken by the Multi-angle Imaging SpectroRadiometer aboard NASA's Terra spacecraft as it passed over Southern California on Jan. 16. The fire burned more than 1,863 acres and forced the evacuation of 3,700 people. (NASA via AP) Back to slideshow navigation
  9. Where stars are born

    An image captured by NASA's Spitzer Space Telescope shows the Orion Nebula, an immense stellar nursery some 1,500 light-years away. This false-color infrared view, released on Jan. 15, spans about 40 light-years across the region. The brightest portion of the nebula is centered on Orion's young, massive, hot stars, known as the Trapezium Cluster. But Spitzer also can detect stars still in the process of formation, seen here in red hues. (NASA / JPL-Caltech) Back to slideshow navigation
  10. Cygnus takes flight

    Orbital Sciences Corp.'s Antares rocket rises from NASA's Wallops Flight Facility on Wallops Island, Va, on Jan. 9. The rocket sent Orbital's Cygnus cargo capsule on its first official resupply mission to the International Space Station. (Chris Perry / NASA) Back to slideshow navigation
  11. A long, long time ago...

    This long-exposure picture from the Hubble Space Telescope, released Jan. 8, is the deepest image ever made of any cluster of galaxies. The cluster known as Abell 2744 appears in the foreground. It contains several hundred galaxies as they looked 3.5 billion years ago. Abell 2744 acts as a gravitational lens to warp space, brightening and magnifying images of nearly 3,000 distant background galaxies. The more distant galaxies appear as they did more than 12 billion years ago, not long after the Big Bang. (NASA / NASA via AFP - Getty Images) Back to slideshow navigation
  12. Frosty halo

    Sun dogs are bright spots that appear in the sky around the sun when light is refracted through ice crystals in the atmosphere. These sun dogs appeared on Jan. 5 amid brutally cold temperatures along Highway 83, north of Bismarck, N.D. The temperature was about 22 degrees below zero Fahrenheit, with a 50-below-zero wind chill.

    Slideshow: The Year in Space (Brian Peterson / The Bismarck Tribune via AP) Back to slideshow navigation
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