Frozen complex organic molecules (COMs) have been found for the first time around a young protostar outside our galaxy. This discovery comes from the James Webb Space Telescope (JWST), which has opened new doors for astrophysics.
Astronomers, led by Marta Sewiło from the University of Maryland, used JWST’s Mid-Infrared Instrument (MIRI) to find these molecules encased in ice around the massive protostar ST6 in the Large Magellanic Cloud (LMC). This nearby dwarf galaxy is about 163,000 light-years away. COMs, which are carbon-containing molecules with over six atoms, could be crucial for life. Some detected include acetaldehyde, acetic acid, ethanol, and methanol.
Sewiło noted, “We’ve only just begun exploring complex organic chemistry in this environment.” The JWST has made it easier to detect these COMs in their icy state, something that has been challenging until now. Typically, such molecules are found in their gas phase around young stars. For instance, methanol and methyl formate have been detected in gas around other protostars, but finding them frozen is rarer.
Understanding these molecules sheds light on the chemistry present at the earliest stages of star formation. Stars are born in massive clouds of cold gas, often below 100 Kelvin. In this cold state, complex molecules exist as ices on dust grains. As the star develops and its core heats up, these ices change into gas.
The LMC presents different conditions compared to the Milky Way. With fewer heavy elements and a higher level of ultraviolet radiation, these factors can influence the formation and abundance of COMs. Understanding the organic chemistry in the LMC offers insight into how life’s building blocks formed in the early universe. Research suggests that the lack of heavy elements in the LMC limits the variety of these complex molecules.
Interestingly, the study found lower overall COM abundance around ST6 compared to previously observed protostars in our own galaxy—except for acetic acid, which appears more abundant due to increased ultraviolet radiation in the LMC.
Among the unknown molecules, researchers suspect the presence of glycolaldehyde, a precursor to ribose, a key component of RNA. While they have hints pointing to it, conclusive evidence requires more laboratory studies for validation.
As ST6 continues to evolve, the heat will turn those icy COMs into gas, allowing further chemical reactions that could lead to larger, life-important molecules, potentially including amino acids. Though researchers haven’t spotted these in ST6 yet, amino acids have been found in comets and meteorites, hinting at chemical pathways that began with the types of COMs discovered.
The implications of this research are significant. They suggest pathways for how life’s building blocks could form beyond our galaxy, broadening our understanding of life’s origins in the universe.
This exciting research was published on October 20 in the Astrophysical Journal Letters. For more information, you can visit Astrophysical Journal Letters.
