Thursday, September 29, 2016

Astronomers Make 1st Accurate Measurement of Oxygen In a Distant Galaxy

Astronomers Make 1st Accurate Measurement of Oxygen In a Distant Galaxy

Ryan Sanders and the CANDELS team

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Astronomers from the University of California Los Angeles made the first accurate measurement of oxygen in a distant galaxy called COSMOS-1908. Using the MOSFIRE (Multi-Object Spectrometer for Infra-Red Exploration) installed on the Keck I telescope, they found that the galaxy contains about 20 percent the amount of oxygen our sun has.

As stated in the Astrophysical Journal Letters, COSMOS-1908 is the most distant galaxy with oxygen we have seen so far. It contains 1 billion stars, significantly fewer than the 100 billion stars in the Milky Way.

They assert that measuring the oxygen is crucial to determining how galaxies form and evolve, the cause of their structural differences and how they interact with the environment. With the help of the telescope located in Hawaii, UCLA professor of astronomy and study co-author Alice Shapley describes the research as looking back in time as COSMOS-1908 was born 12 billion years ago.

The total amount of oxygen in a galaxy relies on the total amount of oxygen from its stars, the oxygen produced by super winds and the oxygen from the intergalactic environment that enters it. Shapley explains that the only way to understand these processes is to measure how much oxygen the galaxy contains.

The Multi-Object Spectrometer for Infra-Red Exploration is a five-ton spectrograph designed to study the farthest and faintest galaxies. This instrument collects visible-light photons from cosmic objects located billions of light years away.

A spectograph also allows astronomers to assess the chemical contents of distant galaxies. These contents include oxygen, iron, hydrogen or carbon, all of which can help experts understand the unique characteristics of a galaxy.

The observation was a difficult task, but the team hopes they could still find more galaxies with oxygen.

“Close galaxies are much brighter, and we have a very good method of determining the amount of oxygen in nearby galaxies,” points out the study’s lead author Ryan Sanders, who is also an astronomy graduate student at the university.