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Molecule detection in young star system challenges search for Life assumptions

Organohalogen methyl chloride discovered by ALMA around the infant stars in IRAS 16293-2422. These same organic compounds were discovered in the thin atmosphere surrounding 67P/C-G by the Rosetta space probe. Credit: B. Saxton (NRAO/AUI/NSF).

SKA Global Headquarters, Jodrell Bank, UK, Thursday 5 October 2018 – Most people aren’t familiar with methyl chloride, but this complex organic molecule was widely believed to be an indicator of Life if detected on another planet. In a recent study published in Nature, an international team of astronomers led by Edith Fayolle (Harvard-Smithsonian Center for Astrophysics) and including SKA Project Scientist Tyler Bourke detected the molecule around an infant star system, putting this theory into question.

The team used the Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile to make the detection in a dusty & cloudy environment containing several proto-stars of similar mass to the Sun, located about 400 light years from Earth.

The molecule was also previously detected in similar abundance by the Rosetta probe around the comet 67P/Churyumov-Gerasimenko. Since comets are remnants of early planetary formation, these new observations support the idea that planetary systems have a similar chemical composition than their parent star-forming regions.

“Methyl chloride is usually associated with industrial and biological activity on Earth, so astrobiologists hoped that the presence of the molecule in an exoplanet’s atmosphere could be used to derive the presence of life on the planet. However, detecting it in systems where stars and planets are still being formed weakens that link” said co-author Tyler Bourke, Project Scientist at SKA Organisation.

ALMA can detect chemical signatures by observing the unique radio emissions emitted by molecules in space. With its broad frequency coverage and high sensitivity, the SKA will complement ALMA by detecting signatures at different frequencies.

“While ALMA will be able to observe down to about 35 GHz, SKA will cover a much lower broad frequency range between 50 MHz and over 15 GHz” said Dr Bourke. “This will allow us to detect other types of biologically interesting molecules, such as amino acids around young stars and observe a later stage of planet formation, making observations using both facilities extremely important to our understanding of how life emerges on other planets.”


Read the news release from ALMA

This research was presented in a paper titled “Protostellar and Cometary Detections of Organohalogens,” by E. Fayolle, et al., appearing in the journal Nature Astronomy [].