A team of international scientists has used NASA’s James Webb Space Telescope to detect a new carbon compound in space for the first time. Known as methyl cation (pronounced cat-eye-on) (CH3+), the molecule is important because it aids the formation of more complex carbon-based molecules. Methyl cation was detected in a young star system, with a protoplanetary disk, known as d203-506, which is located about 1,350 light-years away in the Orion Nebula.
Carbon compounds form the foundations of all known life, and as such are particularly interesting to scientists working to understand both how life developed on Earth, and how it could potentially develop elsewhere in our universe. The study of interstellar organic (carbon-containing) chemistry, which Webb is opening in new ways, is an area of keen fascination to many astronomers.
The unique capabilities of Webb made it an ideal observatory to search for this crucial molecule. Webb’s exquisite spatial and spectral resolution, as well as its sensitivity, all contributed to the team’s success. In particular, Webb’s detection of a series of key emission lines from CH3+ cemented the discovery.
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“This detection not only validates the incredible sensitivity of Webb but also confirms the postulated central importance of CH3+ in interstellar chemistry,” said Marie-Aline Martin-Drumel of the University of Paris-Saclay in France, a member of the science team.While the star in d203-506 is a small red dwarf, the system is bombarded by strong ultraviolet (UV) light from nearby hot, young, massive stars. Scientists believe that most planet-forming disks go through a period of such intense UV radiation, since stars tend to form in groups that often include massive, UV-producing stars.
Typically, UV radiation is expected to destroy complex organic molecules, in which case the discovery of CH3+ might seem to be a surprise. However, the team predicts that UV radiation might actually provide the necessary source of energy for CH3+ to form in the first place. Once formed, it then promotes additional chemical reactions to build more complex carbon molecules.
Broadly, the team notes that the molecules they see in d203-506 are quite different from typical protoplanetary disks. In particular, they could not detect any signs of water.
“This clearly shows that ultraviolet radiation can completely change the chemistry of a protoplanetary disk. It might actually play a critical role in the early chemical stages of the origins of life,” elaborated Olivier Berné of the French National Centre for Scientific Research in Toulouse, lead author of the study.
These findings, which are from the PDRs4ALL Early Release Science program, have been published in the journal Nature.
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Using data from the Spitzer space observatory, Dr Susana Iglesias-Groth, a researcher from The Instituto de Astrofísica de Canarias (IAC), has found evidence for the existence of the amino acid tryptophan in the interstellar material in a nearby star-forming region. The research is published in Monthly Notices of the Royal Astronomical Society.
High amounts of tryptophan were detected in the Perseus Molecular Complex, specifically in the IC348 star system, a star-forming region that lies 1000 light years away from Earth - relatively close in astronomical terms. The region is generally invisible to the naked eye, but shines brightly when viewed in infrared wavelengths.
Tryptophan is one of the 20 amino acids essential for the formation of key proteins for life on Earth and produces one of the richest patterns of spectral lines in the infrared. It was therefore an obvious candidate to be explored using the extensive spectroscopic database of the Spitzer satellite, a space-based infrared telescope.
The analysis of the infrared light emitted from the region revealed 20 emission lines of the molecule tryptophan. The temperature of the tryptophan is about 280 Kelvin, or 7 degrees Celsius. Iglesias-Groth has previously found water and hydrogen at the same temperatures in IC348.
The study suggests that the emission lines associated with tryptophan may also be present in other star-forming regions and that their presence is common in the gas and dust from which stars and planets form.
Amino acids are commonly found in meteorites and were present during the formation of our Solar System. This new work could indicate that these protein-building agents - that are key to the development of life - exist naturally in the regions where stars and planetary systems form and may contribute to the early chemistry of planetary systems around other stars.
Dr Iglesias-Groth says, "The evidence for tryptophan in the Perseus molecular complex should encourage additional effort to identify other amino acids in this region, and in other star-forming regions. It is a very exciting possibility that the building blocks of proteins are widely present in the gas from which stars and planets form - it may be key for the development of life in exoplanetary systems”.
