Astronomers measure helium from the Universe's first five minutes

An international team has measured primordial helium abundance with 0.5% precision, three times better than previous estimates. The result rests on 130 hours of Large Binocular Telescope observations of 15 pristine distant galaxies and appears in five papers in The Astrophysical Journal.

• Primordial helium abundance measured to 0.5% precision, three times better than before
• Based on 130 hours of Large Binocular Telescope observations of 15 ancient galaxies
• More than 10 helium and 15 hydrogen spectral lines analyzed simultaneously
• Helium data used to calculate the number of neutrino families in the early Universe