First stars get 150 million years younger overnight

By Jacob Aron THEY’RE old but not that old. The first stars were born nearly 150 million years later than we thought, according to new data from the European Space Agency’s Planck space telescope. Planck spent three years – between 2009 and 2012 – measuring the cosmic microwave background (CMB). This is the first light released in the universe, 380,000 years after the big bang 13.8 billion years ago. It is leftover radiation released as the hot and dense universe cooled, and is now spread across the entire sky. At the end of its mission, the Planck team released the highest-resolution map ever of the CMB’s temperature, revealing new measurements of all kinds of cosmological details. Since then, the Planck team has been analysing readings of the CMB’s polarisation, which provides another way to study this light. “It’s like having an independent experiment to confirm our results,” says project scientist Jan Tauber. One major finding is that a period called the cosmic dark ages lasted longer than we thought. After the CMB was released, the universe was dominated by a fog of opaque hydrogen gas. It stayed dark for hundreds of millions of years until gravity clumped matter together into the first stars and galaxies, which produced enough radiation to ionise the hydrogen and make it transparent. Astronomers are still short on details about how this lighter period, known as the reionisation era, began and ended. Planck’s predecessor, WMAP, pegged the start of the era to about 420 million years after the big bang, but simulations suggested that wouldn’t give gravity enough time to work its magic and produce stars. Now Planck, like a cosmic bouncer scrutinising a fake ID, has decided that the dates don’t add up. It has pushed back the start of reionisation to about 550 million years after the big bang, making the first stars younger by nearly 150 million years. “Planck, like a cosmic bouncer scrutinising a fake ID, has decided that the dates don’t add up” “If the problem had not been resolved, we would have had to think of weird ways to start the formation of stars,” says Tauber. This article appeared in print under the headline “First stars get 150 million years younger” More on these topics:
  • 首页
  • 游艇租赁
  • 电话
  • 关于我们