An international team of planetologists discovered traces of methyl cation, a positively charged methane ion (CH3+), in gas clusters within the protoplanetary disk in the constellation Orion. This discovery confirmed the hypothesis of the important role of these molecules in the formation of the “building materials” of future planets.
As the scientists report in an article in the journal Nature, theorists had assumed that the process of formation of gaseous organics in the interstellar medium can be triggered methyl cation. However, until now, it could not be detected outside the solar system. Observations made with the JWST orbiting telescope showed that CH3+ is still present in the protoplanetary disk of the Orion star-formation region.
The discovery of a variety of organic molecules in space has forced scientists to think about how organics could arise in the interstellar medium without a constant influx of heat and light. The role of its progenitor has been claimed for more than 40 years by the so-called carbenium, or methyl cation, which is a methane molecule that has had one hydrogen atom taken away.
It is a very unstable substance, which makes it easy to enter into chemical reactions even at extremely low temperatures and in the absence of sources of ionizing radiation. Theorists speculate that interactions between the methyl cation, water, nitrogen, carbon dioxide and other substances found in outer space gave rise to the variety of organics that scientists observe in space today.
The search for the “progenitor of organics”
Despite the great interest in methyl cation, astronomers have not been able to detect traces of it in space outside the solar system. The authors of the new work first obtained evidence of its existence during the observations of the protoplanetary disk d203-506 inside the Orion Nebula, in the closest region of star formation to us, far from Earth by 1.35 thousand light years.
Inside this disk, astronomers suggest, lurks an emerging star whose mass is about five times lower than that of the Sun. Bright ultraviolet radiation of this luminary gradually destroys the protoplanetary disk surrounding it, heating it and highlighting its fringes, which gave scientists the opportunity to study its structure and chemical composition in detail with the James Webb orbiting telescope (JWST), launched into orbit in December 2021.
When scientists began analyzing the infrared spectrum of the protoplanetary disk, they found that methyl cations were present in this gas-dust structure. The researchers note that they cannot be confused with other substances, as all other organic and inorganic molecules have a different pattern of spectral absorption and emission lines.
The scientists suggest that the presence of carbenium ions inside the “hot” part of the disk suggests that they occur during a long chain of reactions, which involves hydrogen molecules, carbon ions and ultraviolet radiation. The authors of the study hope that further observations of other protoplanetary disks will help to confirm this hypothesis and prove that CH3+ plays a critical role in the formation of cosmic organics.