ESO: Best Observational Evidence of First Generation Stars

[bystander]

Best Observational Evidence of First Generation Stars in the Universe
ESO Science Release | VLT | 2015 Jun 17

VLT discovers CR7, the brightest distant galaxy, and signs of Population III stars

Artist’s impression of CR7 (Credit: ESO/M. Kornmesser)

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Astronomers using ESO’s Very Large Telescope have discovered by far the brightest galaxy yet found in the early Universe and found strong evidence that examples of the first generation of stars lurk within it. These massive, brilliant, and previously purely theoretical objects were the creators of the first heavy elements in history — the elements necessary to forge the stars around us today, the planets that orbit them, and life as we know it. The newly found galaxy, labelled CR7, is three times brighter than the brightest distant galaxy known up to now.

Astronomers have long theorised the existence of a first generation of stars — known as Population III stars — that were born out of the primordial material from the Big Bang. All the heavier chemical elements — such as oxygen, nitrogen, carbon and iron, which are essential to life — were forged in the bellies of stars. This means that the first stars must have formed out of the only elements to exist prior to stars: hydrogen, helium and trace amounts of lithium.

These Population III stars would have been enormous — several hundred or even a thousand times more massive than the Sun — blazing hot, and transient — exploding as supernovae after only about two million years. But until now the search for physical proof of their existence had been inconclusive. ...

Scientists Discover Brightest Early Galaxy and Likely First Generation Stars
W.M. Keck Observatory | 2015 Jun 17

Evidence for Pop III-like stellar populations in the most luminous Lyman-α
emitters at the epoch of re-ionisation: spectroscopic confirmation - David Sobral et al

• arXiv.org > astro-ph > arXiv:1504.01734 > 07 Apr 2015 (v1), 04 Jun 2015 (v2)

Identification of the brightest Lyα emitters at z=6.6: Implications for the
evolution of the luminosity function in the re-ionisation era - Jorryt Matthee et al

• Monthly Notices of the RAS 451(1) 400 (2015 July 21) DOI: 10.1093/mnras/stv947
  arXiv.org > astro-ph > arXiv:1502.07355 > 25 Feb 2015 (v1), 29 May 2015 (v2)

[bystander]

CR7 Is Not Alone: A Team of Super Bright Galaxies in the Early Universe
Royal Astronomical Society | NAM2016 | 2016 Jun 27

This illustration of reionisation shows a timeline summarising the evolution of the Universe
running from left to right, where the Big Bang is on the left and the age of the Universe is
about two billion years on the right. It shows how the cosmic “fog" of neutral (uncharged)
hydrogen pervading the early Universe is cleared by the first objects to emit radiation.
Credit: NASA / CXC / M.Weiss.

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Astronomers have identified a family of incredible galaxies that could shed further light on the transformation of the early Universe known as the ‘epoch of reionisation’. Dr David Sobral of Lancaster University will present their results on Monday 27 June at the National Astronomy Meeting in Nottingham.

About 150 million years after the Big Bang, some 13 billion years ago, the Universe was completely opaque to high energy ultraviolet light, with neutral hydrogen gas blocking its passage. Astronomers have long realised that this situation ended in the so-called ‘epoch of reionisation’, where ultraviolet light from the earliest stars broke open neutral hydrogen atoms, and could start to travel freely through the cosmos. This reionisation period marks a key transition between the relatively simple early cosmos, with normal matter made up of hydrogen and helium, and the universe as we see it today: transparent on large scales and filled with heavier elements.

In 2015 Sobral led a team that found the first example of a spectacularly bright galaxy within the epoch of reionisation, named Cosmos Redshift 7 or CR7, which may harbour first generation stars. The team also discovered a similar galaxy, MASOSA, which, together with Himiko, discovered by a Japanese team, hinted at a larger population of similar objects, perhaps made up of the earliest stars and/or black holes. ...