COSMOS 1908: The Galaxy Filled With Abundant Oxygen
September 29, 2017
Astronomers have measured oxygen levels in a galaxy called COSMOS 1908. The findings could help to unravel more about the evolution of galaxies.
A new study suggests a key ingredient needed to support life is in short supply in some distant reaches of the universe.
Astronomers have for the first time accurately measured the amount of oxygen in a distant galaxy around 12 billion light years from Earth.
They found the galaxy, called COSMOS 1908, contains just 20 percent of abundance of oxygen found in our sun.
This gives the oxygen levels relative to other materials in the galaxy.
Our sun currently contains just trace levels of oxygen, suggesting levels of this gas in this relatively young galaxy are still extremely low.
Oxygen is created inside stars and released into the interstellar gas when these stars die.
The findings promise to help reveal new details about distant galaxies, which, due to the time it takes light from them to reach Earth, astronomers are seeing early in the life of the universe.
Researchers say their study could help them understand how galaxies have evolved through time since the Big Bang as oxygen levels have increased.
See Also: Scientists Have Detected Oxygen On Mars!
Early in the universe’s history, there was relatively little oxygen in young galaxies as only the lightest elements – such as hydrogen and helium – were abundant.
Possibly the Oldest Galaxy with Measured Oxygen
Professor Alice Shapley, an astronomer at the University of California Los Angeles, said: ‘This is by far the most distant galaxy for which the oxygen abundance has actually been measured.
‘We’re looking back in time at this galaxy as it appeared 12 billion years ago.’
COSMOS 1908 contains around 1 billion stars, making it far smaller than the Milky Way, which contains around 100 billion.
While measuring oxygen in nearby galaxies has been possible for some time, working out the levels in distant galaxies has not been possible before.
Astronomers instead have to rely on indirect and imprecise techniques for estimating oxygen abundance in far off galaxies.
But in the new study, which is published in the Astrophysical Journal Letters, the researchers have used a direct measurement for the first time.
Mechanism for Measurement
The researchers used an advanced instrument called the Multi-Object Spectrometre for Infrared Exploration (MOSFIRE) at the Keck Observatory in Hawaii.
This collects visible light from distant galaxies to produce a spectrograph, allowing astronomers to determine the chemical contents of galaxies due to the spectral fingerprints they create.
To characterise the chemical contents of COSMOS 1908, the researchers analysed a particular wavelength in the MOSFIRE spectrum of this galaxy that is sensitive to the amount of oxygen.
Professor Shapley said this technique should help to reveal new information about how oxygen is created in distant and very ancient galaxies.
Oxygen largely produced by large stars that explode violently in supernova, sending the gas across the galaxy.
However, oxygen can also be lost to ‘super winds’, which propel the interstellar gases out of galaxies at hundreds of thousands of miles per hour.
‘If we can measure how much oxygen is in a galaxy, it will tell us about all these processes,’ said Shapley.
‘Measuring the oxygen content of galaxies over cosmic time is one of the key methods we have for understanding how galaxies grow, as well as how they spew out gas into the intergalactic medium.’
Universe’s First Oxygen?
Scientists have glimpsed the earliest oxygen ever seen in the universe, in a galaxy 13.1 billion light years away, giving an insight in the universe’s first stars.
Studying heavy elements from this era provides clues about what triggered the nature of the first stars, and how galaxies were born.
Various elements are found around us in the present universe, but just after the Big Bang 13.8 billion years ago only the lightest elements, hydrogen, helium, and lithium, existed.
Heavier elements, such as carbon and oxygen, have been formed in stars and accumulated in the Universe over time.
The researchers found evidence for the oxygen in SXDF-NB1006-2, a galaxy discovered in 2012.
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