Scientists detect oxygen legacy of first stars

[nitpicker]

http://www.bbc.com/news/science-environment-44129714

Scientists detect oxygen legacy of first stars

By Jonathan Amos
BBC Science Correspondent

57 minutes ago

Astronomers have made the most distant ever detection of oxygen. They observed it in a galaxy of stars that existed just 500 million years after the Big Bang. But what is really fascinating is that this oxygen can only have been produced in an even older group of stars that would have dispersed it when they died and blew themselves apart. That means we could be witnessing the traces of events that occurred a mere 250 million years after the Big Bang.

Scientists reporting in the journal Nature say this takes us back into the theorised epoch known as Cosmic Dawn when the Universe was first bathed in light. The team cannot see this critical period directly - it is beyond the capability of current technology. But it augurs well for future telescopes that will be tuned to see the dawn - namely, the James Webb space observatory, which is due for launch in 2020. This mission, the successor to Hubble, will carry an immense mirror and instruments that are designed specifically to detect the glow coming from the very first population of stars.

The distance to the reported galaxy - called MACS1149-JD1 - was confirmed with the Atacama Large Millimetre/Submillimetre Array (Alma), and the European Southern Observatory's Very Large Telescope (VLT). These facilities studied spectral lines from hydrogen - in the case of the VLT - and from oxygen - in the case of Alma.

They found both these emissions to have been shifted to longer wavelengths by the expansion of the Universe. "The horizon for this particular object is what we call a Redshift 9.1," explained Richard Ellis, a professor of astrophysics at University College London, UK. "That means the Universe has expanded nine to 10 times since the light left this object. We're looking back about 97% of the way to the Big Bang (13.8 billion years ago) when the Universe was only about 500 million years old.
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[Nitram]

1. When I took a course in stars and galaxies I was amazed how astronomers developed techniques

for learning about extremely distant object by by analyzing the only evidence they could observe: electromagnetic radiation: light, X-rays, radio waves, etc. Such a great example of the power of the scientific method.