Tuesday, June 14, 2016

‘Wasteful’ galaxies don’t recycle as much as we thought 
Without heavy elements you couldn’t read this because you wouldn’t exist. In fact no life would, or any planets anywhere in the universe.
Vital heavy elements such as carbon, oxygen and zinc are made by fusing lighter elements together under incredible conditions of intense heat, pressure and energy found inside the heart of stars, or during violent supernova explosions.
It’s amazing that many of the atoms in your body were forged during nuclear explosions deep within stars and then blasted into space when they died. But it turns out that this process is pretty wasteful, and that enormous quantities of these precious elements are lost when explosions from supernovae and supermassive black holes propel them far beyond galaxies - sometimes up to a million light years into deep space.
An international research team showed that more oxygen, carbon and iron atoms exist in the sprawling, gaseous halos outside of galaxies than within them, depriving galaxies of raw materials for stars and planets.
The near-invisible reservoir of gas that surrounding a galaxy is called the circumgalactic medium (CGM). Using a $70m instrument on board the NASA Hubble Space Telescope the researchers analysed the composition of the CGM, which is near-invisible to human eyes. They were surprised to see so many heavy elements in the CGM as the assumption had been that these elements would be reused to new planets and stars more efficiently.
But as lead author Benjamin Oppenheimer, a research associate in the Center for Astrophysics & Space Astronomy at CU-Boulder, said: “As it turns out, galaxies aren’t very good at recycling.”  

Images: Adrien Thob, LJMU, and NASA

The paper is published in Monthly Notices of the Royal Astronomical Society

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