Astronomers Find First Fully Deuterated Methanol in Space, Around a Baby Star 1,000 Light-Years Away
ALMA's COMPASS survey also found methanol masers around more than half of the young stars studied, hinting that complex organic chemistry starts earlier than thought.
An international team using the Atacama Large Millimeter/submillimeter Array (ALMA) has detected a rare, fully heavy form of methanol in space for the first time, and found that young, still-forming stars are wrapped in a more sophisticated chemical starter kit than expected. The results come from the ALMA COMPASS Large Program, short for Complex Organic Molecules in Protostars with ALMA Spectral Surveys, and appear in seven papers in Astronomy & Astrophysics.
COMPASS studies 11 nearby, sun-like infant stars and needed more than 100 hours of telescope time. By combining signals from up to 66 of its dishes, ALMA picks up the faint spectral fingerprints of organic molecules and maps where they sit around the young stars, on scales comparable to our own solar system. "We are getting completely new insights into the complex chemistry occurring around the youngest protostars," said Jes Jørgensen, a professor at the Niels Bohr Institute of the University of Copenhagen and the program's principal investigator.
The headline detection is CD3OD, or fully deuterated methanol, in which all of the simple alcohol's hydrogen atoms are replaced by deuterium, a heavier form of hydrogen. Arnaud Belloche of the Max Planck Institute for Radio Astronomy led the paper and found it around the young protostar IRAS 4A2 in the Perseus molecular cloud, about 1,000 light-years from Earth. It is the first time the molecule has been seen in space.
A second result concerns methanol masers, natural radio beacons produced by methanol molecules. A paper led by Seoul National University graduate student Jae-Hong Jeong shows that this emission is far more widespread around low-mass protostars than previously thought. The data reveal masers around more than half of the young stars studied, suggesting they may be a common feature of early stellar evolution that shows up when observations are sensitive enough.
Methanol is the simplest alcohol and plays a central role in building larger organic molecules. "The interesting question is how these chemical ingredients may influence the conditions on planets and potentially the origin of life there," Jørgensen said. Adele Plunkett of the NSF National Radio Astronomy Observatory, one of four co-principal investigators, said COMPASS lets astronomers for the first time systematically compare protostars from different environments and evolutionary stages.
The team says this is only the first step. Analysis will extend to all detected species across all 11 sources, to determine whether differences in chemical makeup come from the stars' birth environments or from evolution during star formation. Jeong-Eun Lee of Seoul National University said the team is "just beginning to tap into the richness of this data set."
