Distant galaxy hints at universe's earliest stars

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Atacama Large Millimeter/submillimeter Array (ALMA) and ESO's Very Large Telescope (VLT) have captured the evidence on star formation in the very distant galaxy MACS1149-JD1 suggesting that the formation started at an unexpectedly early stage, only 250 million years after the Big Bang.

Astronomers published their research on 16 May in the journal Nature.

Bouwens emphasised that it was still not clear whether the stellar activity detected in MACS1149-JD1 occurred in other regions in the early Universe, but he added that the discovery would spur similar studies of other galaxies.

This image shows the huge galaxy cluster MACS J1149.5+223, whose light took over 5 billion years to reach us. Here, the oxygen distribution detected with ALMA is depicted in green.

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"The mature stellar population in MACS1149-JD1 implies that stars were forming back to even earlier times, beyond what we can now see with our telescopes", says Nicolas Laporte, an astronomer on the research team.

The distance to the galaxy determined from this observation is consistent with the distance from the oxygen observation.

Oxygen, carbon, and nitrogen will only form in the universe after stars first fusion and then die, spewing these elements into interstellar space. That gives us an indication of how much earlier in the history of the Universe - which we can't now probe with our telescopes - that this object actually formed.

Scientists have described the detection of such distant oxygen as a discovery that fundamentally changes our understanding of the origin of the universe, and is a major breakthrough in space exploration. But for the galaxy to have enough oxygen to be visible, it must have been creating stars for around 250 million years before that, making it one of the earliest known star-producing galaxies.

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For the new study, both teams collaborated to discover the signal at 13.28 billion light years - the furthest distance yet. That gives us an indication of how much earlier in the history of the Universe - which we can't now probe with our telescopes - that this object actually formed.

The scientists also reconstructed the earlier history of MACS1149-JD1 using infrared data taken with the NASA/ESA Hubble Space Telescope and NASA's Spitzer Space Telescope.

For the first few hundred million years after the Big Bang, the universe was a very cold, dark place.

The results demonstrate the usefulness of ALMA as a tool for measuring the red shift of distant galaxies, Rychard Bouwens, an astrophysicist at Leiden University, said in another article in Nature. With MACS1149-JD1, we have managed to probe history beyond the limits of when we can actually detect galaxies with current facilities.

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The team is quite not finished with MACS1149-JD1. But the precision of that distance measurement with is significantly lower than that of MACS1149-JD1 which is based on the use of two independent emission lines from atoms of hydrogen and oxygen.