Evidence for Stars Forming Just 250 Million Years After The Big Bang

This image shows the galaxy cluster MACS J1149.5+2223 the inset image is the distant galaxy MACS1149-JD1 with the oxygen distribution depicted in red. Image ALMA NASA  ESA HST W. Zheng

"The presence of oxygen in MACS1149-JD1 therefore indicates that a previous generation of stars had already formed and died at an even earlier time".

The Atacama Large Millimeter/submillimeter Array (ALMA) is not your standard, run-of-the-mill telescope. It was then revived at the epoch of the ALMA observations: 500 million years after the Big Bang.

Astronomers have observed a galaxy 13.3 billion light years away that includes stars that must have been shining just 250 million years after the Big Bang.

Pinpointing this period of star birth - which gave rise to oxygen, carbon and other elements in the Universe - is a holy grail for astronomers chasing down the beginning of everything.

To determine when these earlier stars were formed, the team used infrared data taken with the Hubble Space Telescope and the Spitzer Space Telescope and discovered that the observed brightness of the galaxy is well-explained by a model where the onset of star formation corresponds to only 250m years after the universe began. As this infrared light traversed space, the extension of the Universe extended it to wavelengths in excess of ten times longer when it achieved Earth and was identified by ALMA.

"These results demonstrate the ability of ALMA as a tool to measure the redshift of distant galaxies", says Richard Bouwens, of the University of Leiden in the Netherlands, in the paper issued in the Nature journal. This is because stars are the burning crucibles that convert hydrogen and helium into larger elements - without stars, there is no oxygen."I was thrilled to see the signal of the distant oxygen in the ALMA data", said lead author Takuya Hashimoto, a researcher at Osaka Sangyo University and the National Astronomical Observatory of Japan, in a press release.

Nicolas Laporte, a researcher at University College London (UCL) in the United Kingdom said, "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".

The real breakthrough was the detection of oxygen in the galaxy, which is observable in the Leo constellation, though not with the naked eye.

"With MACS1149-JD1, we have managed to probe history beyond the limits of when we can actually detect galaxies with current facilities". This makes MACS1149-JD1 the most distant galaxy with a precise distance measurement.

"This has very exciting implications for finding "cosmic dawn" when the first galaxies emerged", he added. "With these new observations of MACS1149-JD1 we are getting closer to directly witnessing the birth of starlight". 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". "It is truly remarkable that ALMA detected an emission line - the fingerprint of a particular element - at such a record-breaking distance", Zheng said.



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