First stars formed 250 million years after Big Bang

Pablo Tucker
May 17, 2018

The galaxy, MACS1149-JD1, is 13.28 billion light years away and contains the most distant detected source of oxygen. The VLT helped in studying the "spectral lines from hydrogen" and the Alma helped in studying the "spectral lines from oxygen".

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.

"This is an exciting discovery as this galaxy is seen at a time when the Universe was only 500 million years old and yet it already has a population of mature stars", added Dr. Nicolas Laporte, a postdoctoral researcher at University College London. This period, commonly referred to as "cosmic dawn, ' is of particular interest because it marked the transition from a hot, dense, and almost homogeneous universe to the universe we are more familiar with today - one filled with stars, planets, nebulae, and people".

A team of astronomers using high-precision optical instruments were able to explore the galaxy under the code name MACS1149-JD1, which is considered the most remote from Earth, finding in it the presence of oxygen.

As this infrared light traveled across space, the expansion of the Universe stretched it to wavelengths more than 10 times longer by the time it reached Earth and was detected by ALMA.

"This galaxy is seen at a time when the universe was only 500m years old and yet it already has a population of mature stars", said Nicolas Laporte, a researcher at University College London in the United Kingdom and second author of the new paper.

Astronomers have observed a galaxy a very distant 13.28 billion lightyears away, zooming in closer than ever to the "cosmic dawn" of the Universe's first stars, they said Wednesday.

A weaker hydrogen emission also was observed by the VLT, indicating a distance consistent with the oxygen observation.

The real breakthrough was the detection of oxygen in the galaxy, which is observable in the Leo constellation, though not with the naked eye. They measured the frequency of a peak in the galaxy's spectrum that comes from ionized oxygen gas.

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 a period after the Big Bang, there was no oxygen in the Universe; it was made by the combination procedures of the primary stars and afterward discharged when these stars kicked the bucket.

By establishing the age of MACS1149-JD1, the team has effectively demonstrated the existence of early galaxies to times earlier than those where we can now directly detect them. Whether MACS1149-JD1 is just an outlier or the tip of an iceberg will have to wait for more observations. "With these new observations of MACS1149-JD1 we are getting closer to directly witnessing the birth of starlight".

'Since we are all made of processed stellar material, this is really finding our own origins'.

"With this discovery we managed to reach the earliest phase of cosmic star formation history", said Hashimoto.

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