Far-Off Oxygen Proves These Ancient Stars Formed Just After the Big Bang

Thursday, 17 May 2018 - 7:46PM
Space
Astronomy
Thursday, 17 May 2018 - 7:46PM
Far-Off Oxygen Proves These Ancient Stars Formed Just After the Big Bang
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ALMA (ESO/NAOJ/NRAO), NASA/ESA Hubble Space Telescope, W. Zheng (JHU), M. Postman (STScI), the CLASH Team, Hashimoto et al.
We're fairly used to oxygen here on Earth, so it may not be initially clear why it's so exciting that astronomers found some out on the fringes of observable space.

But it is deeply unusual, and it comes with some fascinating implications: a team of astronomers using the ALMA telescope in Chile have detected a faint glow coming from oxygen about 13.3 billion lightyears away. Oxygen is released by dying stars, and considering that the universe is only about 13.8 billion years old, this would mean the light started traveling extremely early in the universe's life.

So essentially the team, who just published their research in Nature, have found evidence of aging stars which dates back to 500 million years after the Big Bang, which is extremely short when talking about the universe. And since stars generate oxygen during their initial fusion, but only release it when they die out, it would mean that the universe already had stars that lived full lives this early in cosmic history.



The ionized oxygen was found while the team were looking at the ancient galaxy MACS1149-JD1, which is already known to be one of the farthest galaxies in the known universe at 13.2 billion lightyears away. Once they found evidence of aging stars, the next question was fairly straightforward: when did those stars first form?

By using computer models based on the observable brightness from the oxygen, it would make sense that the stars had formed about 250 million years after the Big Bang. According to the study's co-author Richard Ellis, this is a big deal - he said the following in a statement from the European Southern Observatory (who co-manages the ALMA telescope):

Opening quote
"Determining when cosmic dawn occurred is akin to the Holy Grail of cosmology and galaxy formation. 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."
Closing quote


We'd found some previous indications of stellar activity dating back to 13.6 billion years old, but this is much more direct evidence. Now, it's still not as direct as it could be, as we're looking at the oxygen left behind after these first stars died.

But as Ellis said, we're getting a lot closer to finding that "cosmic dawn".
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