Lanzarote-linked astronomy breakthrough: IAC researchers detect elusive molecule around a dying star
A remarkable piece of space science with strong links to the Canary Islands has been announced today, after researchers from the Instituto de Astrofísica de Canarias (IAC) helped make the first secure detection of the methyl radical, CH₃, around an evolved carbon-rich star.
The discovery was made using NASA's James Webb Space Telescope (JWST), but the research is being led by an international team that includes scientists from the IAC. For people living in or visiting Lanzarote, it is another reminder that the Canary Islands play a major role in modern astronomy and the study of the Universe.
What exactly has been discovered?
The molecule at the centre of the discovery is the methyl radical, written by scientists as CH₃. It consists of one carbon atom and three hydrogen atoms, but it is unusually reactive because it has an unpaired electron.
That makes it both scientifically important and extremely difficult to observe. Methyl radicals are short-lived and readily react with other molecules, so astronomers have had very few opportunities to detect one directly in space.
The new observation concerns SMP LMC 011, a highly evolved, carbon-rich star located in the Large Magellanic Cloud, a small galaxy that orbits our Milky Way. The star is approaching the final stages of its stellar evolution and is surrounded by gas and dust produced during its life.
Why was it so difficult to see?
One of the most interesting parts of the discovery is how hard the molecule is to detect.
Many molecules in space can be identified through radio signals. CH₃ is different. Because of its symmetrical structure, it does not produce the type of radio signal astronomers normally use to identify molecules. Instead, researchers had to look for a particular vibrational signature in mid-infrared light.
That presented another problem: Earth's atmosphere blocks the relevant wavelength. The observation therefore required a space-based telescope.
This is where the James Webb Space Telescope became crucial. Its Mid-Infrared Instrument, known as MIRI, was able to examine the region around the distant star in enough detail to identify the methyl radical and estimate how much of it was present.
An unexpected amount of methyl
The researchers found considerably more CH₃ than standard gas-phase chemistry would be expected to produce.
One possibility is that ultraviolet radiation from the dying star is breaking apart molecules such as methane, creating methyl radicals. However, the quantity detected appears too large for that process alone.
The team proposes another source: carbon-rich dust grains surrounding the star.
The dust is thought to contain a disordered carbon-and-hydrogen material known as hydrogenated amorphous carbon. According to the researchers, ultraviolet radiation and/or shocks may be eroding these grains and releasing methyl radicals into the surrounding gas.
In simple terms, the dust around the star may not just be a place where material accumulates. It could also be supplying fresh ingredients for further chemical reactions.
A possible pathway towards more complex molecules
This is where the discovery becomes particularly interesting for our understanding of the Universe.
The star is unusually rich in benzene, a simple aromatic molecule that forms the basic ring structure found in much larger carbon-based compounds. The researchers suggest that methyl radicals can attach themselves to benzene and related molecules.
Those reactions could help build progressively more complicated aromatic molecules, including substances such as toluene and ethylbenzene. These molecules are related to the chemistry that eventually produces larger carbon structures, including polycyclic aromatic hydrocarbons, or PAHs, which are widespread throughout space.
The team also looked for ethane, which could have been produced if methyl radicals simply reacted with one another. They did not detect it. That absence supports the idea that the methyl radicals may instead be taking part in reactions that help build more complex carbon chemistry.
Why does this matter?
Astronomy is not only about discovering distant stars and planets. Researchers are also trying to understand how the chemical ingredients found throughout space are created, changed and recycled.
Evolved stars are important sources of carbon-rich material. As stars reach the later stages of their lives, they can release dust and molecules into their surroundings. That material can eventually become part of the wider interstellar environment from which new stars and planetary systems form.
The new result therefore provides an important clue about how relatively simple carbon chemistry can develop into increasingly complex molecules in space.
What does this have to do with the Canary Islands?
The discovery has a direct Canary Islands connection because researchers from the Instituto de Astrofísica de Canarias are part of the international study.
The IAC is one of the major astronomical research institutions in Spain and operates some of the world's important astronomical facilities in the Canary Islands. The islands' clear skies, high-altitude observatories and relatively stable atmospheric conditions have made them an important location for astronomy and astrophysics.
Although the star studied in this research is nowhere near the Canary Islands, the science behind the discovery is another example of the international astronomical work being carried out by researchers connected with the islands.
For visitors to Lanzarote, it is also a fascinating reminder that the Canary Islands are about much more than beaches, volcanoes and sunshine. The archipelago has a long-standing connection with space science, and the night sky remains one of its natural treasures.
The bigger picture
The detection of CH₃ does not mean that scientists have discovered life or a new form of life-supporting chemistry. Instead, it provides a new piece of evidence about how carbon-containing molecules can be produced and transformed in extreme environments around dying stars.
The researchers say current chemical models will need to take these reactions into account to better understand the formation of complex hydrocarbons around evolved stars.
For anyone interested in astronomy in the Canary Islands, it is a particularly interesting development: a tiny, highly reactive molecule has provided scientists with a new clue about the huge chemical processes that help shape the Universe.
And it is another impressive example of how research connected to the Canary Islands is helping us understand what is happening far beyond our own planet.
