How does star-making pollutes the cosmos?

Galaxies pump out contaminated exhausts.


Using a new imaging system at the WM Keck Observatory in Hawaii, astronomers reveal that galaxies pollute the environment they exist in. They found that the inside of the galaxy is much cleaner than what flows out. 

The team used the Keck Cosmic Web Imager to confirm that the enormous gas used in making stars eventually drive a huge amount of material back out of the system. This stuff is not clean, instead, it contains several elements like oxygen, carbon, and iron.

For this study, a team of astronomers at ARC Centre of Excellence for All-Sky Astrophysics in 3 Dimensions (ASTRO 3D) focused on a galaxy called Mrk 1486. Mrk 1486 is located about 500 million light-years from the Sun.

Astronomers found the galaxy as the perfect source for observation as it lies ‘edge-on to Earth. It means the outflowing gas could be easily viewed and its composition measured.

Galaxies pump out contaminated exhausts
Credit: James Josephides, Swinburne Astronomy Productions

Dr. Alex Cameron, who has recently moved from the University of Melbourne in Australia to the UK’s University of Oxford, said, “We found there is a very clear structure to how the gases enter and exit. Imagine the galaxy is a spinning frisbee. The gas enters relatively unpolluted from the cosmos outside, around the perimeter, and condenses to form new stars. When those stars later explode, they push out other gas – now containing these other elements – through the top and bottom.”

Co-lead author Deanne Fisher, associate professor at the Centre for Astrophysics and Supercomputing at Swinburne University in Australia, said, “The elements – comprising more than half the Periodic Table – are forged deep inside the cores of the stars through nuclear fusion. When the stars collapse or go nova, the results are catapulted into the Universe – where they form part of the matrix from which newer stars, planets, asteroids, and, in at least one instance, life emerges.”

“This work is important for astronomers because, for the first time, we’ve been able to put limits on the forces that strongly influence how galaxies make stars. It takes us one step closer to understanding how and why galaxies look the way they do – and how long they will last.”

Journal Reference:
  1. Alex J. Cameron et al. The DUVET Survey: Direct Te-based Metallicity Mapping of Metal-enriched Outflows and Metal-poor Inflows in Markarian 1486. DOI: 10.3847/2041-8213/ac18ca
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