For the first time in history , a team of astronomers has discovered in the vicinity of a young star and a comet, a molecule previously considered a useful marker of life as we know it: Freon-40. This finding determines that organohalogens – which contain carbon and hydrogen linked to a halogen, in this case chlorine – may not be as good markers of the presence of life, although it would suggest that these ingredients are inherited during the formation phase of planets. .
Observations made with the ALMA ( Atacama Large Millimeter / submillimeter Array ) telescope and ESA’s Rosetta mission, around the child star system IRAS 16293-2422, located about 400 light years away from Earth and the famous comet 67P / Churyumov-Gerasimenko in our own Solar System, resulted in the detection of traces of Freon 40, also known as methyl chloride and chloromethane. This is the first time that a halogenated organo has been detected in interstellar space, complicating the possibility of finding molecules that could indicate the presence of life beyond Earth.
On Earth we already know that these compounds are created by some biological processes as well as by industrial processes such as the production of medicines. But the discovery of this compound in a place prior to the origin of life, fills the path with new obstacles to finding life. We hoped that this molecule could be used as a biomarker, but now it seems that biology is not necessary, underscoring how difficult the search for life beyond our blue world will be.
“We simply did not predict their formation and we were surprised to find it at such concentrations. It is now clear that these molecules form easily in stellar nurseries, providing important information on the chemical evolution of planetary systems, including our own”, explains Karin Öberg , co-author of the work in the journal Nature Astronomy.
The chemical was also found in the thin atmosphere of Comet 67P / Churyumov-Gerasimenko by the Rosetta orbiter.
“Based on our discovery, it is likely that organohalogens are a component of the so-called ‘primordial soup’ , both on young Earth and on nascent rocky exoplanets,” clarifies Öberg.
The investigation of exoplanets – we already know more than 3000 exoplanets – has taken a step beyond the mere location of worlds, but the aim is the search for chemical markers that could indicate the potential presence of life. Hence, determining which molecules could indicate life is a vital step in doing so, but in light of the latest results, establishing reliable markers remains a difficult process.
It seems that we were following a wrong path, because organohalogens instead of indicating the presence of life, could be an important element in the chemistry of the origin of life.
“Our results show that we still have a lot to learn about the formation of organohalogens. It will be necessary to carry out additional searches for organohalogens around other protostars and comets to find the answer” , comments Edith Fayolle, co-author of the work.
Reference: Protostellar and cometary detections of organohalogens, Nature Astronomy (2017). DOI: 10.1038 / s41550-017-0237-7
Image credit: B. Saxton (NRAO / AUI / NSF); NASA / JPL-Caltech / UCLA
