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Dying Stars Create New Frontiers in Space Research

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When William Herschel looked through his telescope in the 1780s he observed what he thought were giant gas clouds in the night sky that he and his sister Caroline documented in the Catalogue of One Thousand New Nebulae and Clusters of Stars.

In fact Herschel, as other early astronomers had, was looking at stellar winds of ionized gas and other materials that were ejected from dying stars in a process lasting tens of thousands of years. He invented the term planetary nebula to describe the expanding gas shell.

These massive, multi-coloured eruptions frequently form spectacular butterfly shapes and have since been documented in fascinating detail by scientists using modern telescopes that have allowed them to identify many of their component compounds.

But it was only in 2000 that a Hong Kong astronomer discovered that dying Sun-like stars are able to produce complex organic material when they erupt. Using space-based infrared telescopes, Professor Sun Kwok found that compounds with aromatic and aliphatic structures can be synthesized rapidly in the late stages of stellar evolution and they can form a small part of planetary nebula.

Professor Kwok from the University of Hong Kong, who specializes in research on interstellar chemistry and stellar evolution and is widely recognized for his theory on the origin of planetary nebulae, calls this material MAON, standing for mixed aromatic/aliphatic organic nanoparticles.

“What we have discovered is that stars in the very last stage of their lives are able to produce very complex organics,” Professor Kwok said. “Not only are they able to make these things, they are ejecting them in the form of a stellar wind and sending them all across the Milky Way galaxy.”

This discovery has changed the way astronomers study this little-understood aspect of space research and has opened up the debate about the origins of life on earth. These star-manufactured compounds are now known to have spread widely throughout the Galaxy and are believed to have played a role in the chemical enrichment of the early solar system.