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17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
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A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
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The Dawn of Light
2 November 2005 (All day)
Astronomers have detected the collective glow from the universe's first stars, providing the first direct observation of a class of stars that hasn't existed for billions of years.
The earliest generation of stars, called population III, formed a few hundred million years after the big bang out of gas that was essentially only hydrogen and helium. Simulations have shown that the lack of heavier elements such as carbon and oxygen required these first stars to be huge--more than 100 times the mass of our sun. Such behemoths would have burned brighter than 10,000 typical modern stars, but only for a few million years. When they died, their ashes seeded the next generation of stars.
Now, astrophysicist Alexander Kashlinsky of Goddard Space Flight Center in Greenbelt, Maryland, and colleagues have found what they believe is a signature of these stars in infrared data from the Spitzer Space Telescope. The scientists analyzed the pattern of light in three small patches of sky, subtracting light from known stars and galaxies and accounting for dust in our own galaxy and solar system. Scattered throughout these patches, the astronomers found several bright spots, which appear to be imprints from the dawn of starlight, the authors conclude 3 November in Nature.
The bright clumps are not individual stars, which are too small to be seen, but regions of increased gas density. Just as tall mountains are more likely to be found in a mountain range, stars are more likely to be found in these denser places in space, Kashlinsky explains. However, these clumps could be confused with clusters of faint galaxies not detected by Spitzer, cautions astronomer Richard Ellis of the California Institute of Technology in Pasadena. Still, he believes the researchers make a reasonable argument that the spots are too bright to be anything but light from the first stars.
The fact that astronomers have not observed minigalaxies of population III stars in other surveys concerns Andrea Ferrara of SISSA/International School for Advanced Studies in Trieste, Italy. But Ellis notes that the first stars may have signed off well before galaxy formation--timing that will need to be confirmed by future observations.