Ancient gas cloud may be a relic from the death of first stars

January 8, 2016
Ancient gas cloud may be a relic from the death of first stars
A simulation of the first stars in the Universe, showing how the gas cloud might have become enriched with heavy elements. The image shows one of the first stars exploding, producing an expanding shell of gas (top) which enriches a nearby cloud, embedded inside a larger gas filament (centre). The image scale is 3,000 light years across, and the colourmap represents gas density, with red indicating higher density. Credit: Britton Smith, John Wise, Brian O'Shea, Michael Norman, and Sadegh Khochfar

Researchers from Australia and the USA have discovered a distant, ancient cloud of gas that may contain the signature of the very first stars that formed in the universe.

The gas cloud has an extremely small percentage of , such as carbon, oxygen and iron – less than one thousandth the fraction observed in the Sun.

It is many billions of light years away from Earth, and is observed as it was just 1.8 billion years after the Big Bang. The observations were made by the Very Large Telescope in Chile.

"Heavy elements weren't manufactured during the Big Bang, they were made later by stars," says lead researcher, Dr Neil Crighton, from Swinburne University of Technology's Centre for Astrophysics and Supercomputing.

"The first stars were made from completely pristine gas, and astronomers think they formed quite differently from stars today."

The researchers say that soon after forming, these first stars – also known as Population III stars – exploded in powerful supernovae, spreading their heavy elements into surrounding pristine clouds of gas. Those clouds then carry a chemical record of the first stars and their deaths, and this record can be read like a fingerprint.

"Previous clouds found by astronomers show a higher enrichment level of heavy elements, so they were probably polluted by more recent generations of stars, obscuring any signature from the first stars," Dr Crighton says.

"This is the first cloud to show the tiny heavy element fraction expected for a cloud enriched only by the first stars," co-author Swinburne's Professor Michael Murphy says.

The researchers hope to find more of these systems, where they can measure the ratios of several different kinds of elements.

"We can measure the ratio of two elements in this cloud - carbon and silicon. But the value of that ratio doesn't conclusively show that it was enriched by the first stars; later enrichment by older generations of stars is also possible," another co-author, Professor John O'Meara from Saint Michael's College in Vermont, USA, says.

"By finding new where we can detect more elements, we will be able to test for the unique pattern of abundances we expect for enrichment by the first ."

The paper will be published in the Monthly Notices of the Royal Astronomical Society Letters on 13 Jan 2016, and is available as a pre-print at http://arxiv.org/pdf/1512.00477v1 .

Explore further: Chemical fingerprints of ancient supernovae found

More information: Possible Population III Remnants at Redshift 3.5. arXiv:1512.00477 [astro-ph.GA] arxiv.org/abs/1512.00477

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Tuxford
2.6 / 5 (5) Jan 08, 2016
"This is the first cloud to show the tiny heavy element fraction expected for a cloud enriched only by the first stars," co-author Swinburne's Professor Michael Murphy says.

Yea, previous observations of early galaxies have already shown an unexpected abundance of metals. So finally, at least one contrary observation to support the fantasy. Whew!

Gas clouds form naturally even now deep within intergalactic space, albeit very slowly. Since the spontaneous generation of new matter in empty space is mostly of hydrogen ions, these clouds would be largely devoid of metals. This is likely simply a distant example.

See, there are alternatives to consider. No need to rush back to the safety of the fantasy so quickly.
HannesAlfven
2 / 5 (4) Jan 08, 2016
I am struck by the confident tone of the article. Such a tone is not appropriate for a topic that truthfully exists at the very edge of (if not beyond) empirical science. We can formulate alternative explanations if we decide to create a protected path for their elaboration. Until then, people have nothing that exists at a similar level of elaboration to compare this against, and therefore no meaningful ability to judge the information.
my2cts
3.7 / 5 (3) Jan 08, 2016
Gas clouds form naturally even now deep within intergalactic space, albeit very slowly. Since the spontaneous generation of new matter in empty space is mostly of hydrogen ions,

Fantasy indeed.
these clouds would be largely devoid of metals. This is likely simply a distant example.

Confirmational bias.

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