Recent discoveries led by MIT Professor Brett McGuire have confirmed the existence of a new molecule in outer space. The groundbreaking research, detailed in the open-access paper “Rotational Spectrum and First Interstellar Detection of 2-Methoxyethanol Using ALMA Observations of NGC 6334I,” was published in the April 12 edition of The Astrophysical Journal Letters.
Lead author Zachary T.P. Fried, a dedicated graduate student in the McGuire group, meticulously pieced together data collected from various international locations, including France, Florida, Virginia, and Copenhagen, reaching this remarkable conclusion.
“Our goal is to understand the molecules present in regions where stars and solar systems are born,” Fried explains. “By studying the rotational spectra of these molecules—the unique light patterns emitted as they spin in space—we can trace the evolution of chemistry alongside star and planet formation. Every molecule has a distinct ‘fingerprint’ that identifies it. To locate new molecules, we identify the molecules we aim to detect, record their spectra in the lab, and then search for these unique patterns using telescopes.”
Exploring Molecular Presence in Space
The McGuire Group has recently employed machine learning to identify promising target molecules for exploration. In 2023, their advanced model recommended focusing on 2-methoxyethanol.
“There are several ‘methoxy’ molecules recognized in space, such as dimethyl ether and methyl formate, but 2-methoxyethanol is the most complex molecule ever detected,” says Fried. To successfully identify this molecule, the researchers first analyzed its rotational spectrum on Earth. Collaborating with teams from the University of Lille (France), New College of Florida, and MIT, they measured the spectrum across a wide frequency range from microwaves to sub-millimeter waves (approximately 8 to 500 gigahertz).
The collected data enabled the search for this molecule using observations from the Atacama Large Millimeter/submillimeter Array (ALMA) in two different star-forming regions: NGC 6334I and IRAS 16293-2422B. The team conducted a thorough analysis of these observations in conjunction with experts from the National Radio Astronomy Observatory in Charlottesville, Virginia, and the University of Copenhagen, Denmark.
“Ultimately, we were able to detect 25 rotational lines of 2-methoxyethanol that corresponded with the molecular signal observed in NGC 6334I (the barcode matched!), confirming our detection of 2-methoxyethanol in this area,” Fried elaborates. “This enabled us to derive important physical characteristics of the molecule, like its abundance and excitation temperature, and explore potential chemical formation pathways from known interstellar precursors.”
Looking Ahead
Discoveries like this enhance our understanding of how molecular complexity arises in space during star formation. The molecule 2-methoxyethanol boasts 13 atoms, making it relatively large by interstellar standards—only six species exceeding 13 atoms had been detected beyond our solar system as of 2021, many through McGuire’s work, and all had ringed structures.
“Ongoing observations of large molecules and analyses of their abundances drive our knowledge of how efficiently large molecules form and the specific reactions involved in their creation,” notes Fried. “Our detection of this molecule in NGC 6334I, but not in IRAS 16293-2422B, offered a unique chance to explore how different physical conditions in these regions influence the chemistry that occurs.”
Photo credit & article inspired by: Massachusetts Institute of Technology
