Methanol, coming as part of the ‘chemical starter kit’ around young stars, has produced some unexpected surprises that could ultimately reveal some of the conditions in which planets and potentially life form around protostars.
The methanol discoveries were made by astronomers using ALMA (the Atacama Large millimeter/submillimeter Array) in the Atacama Desert in Chile, as part of a project called COMPASS (the Complex Organic Molecules in Protostars with ALMA Spectral Surveys).
“Our work provides insight into the complex chemistry of young star systems and is ultimately an important piece of the puzzle in understanding the origin of life,” said University of Bern astrophysicist Maria Drozdovskaya, who leads the COMPASS project, in a statement.
Drozdovskaya’s multinational team of more than 30 astronomers has been chasing down complex organic molecules, large molecules that include carbon atoms, in the planetary construction yards around eleven young stars.
These molecules form part of the chemical inventory that ultimately builds planets and, perhaps, even life that will one day live on those planets.
Methanol matters
Methanol (CH3OH) is important because it is highly abundant in star- and planet-forming regions. In fact, it’s the most abundant complex organic molecule to be found in interstellar space, and is commonly found in planet-forming disks.
Its sheer abundance means that, of all the molecules found around young stars, methanol is the easiest in which to detect different forms where regular hydrogen atoms are replaced by a heavier isotope of hydrogen called deuterium.
How many molecules contain these heavier isotopes is highly dependent upon the conditions in which planets are forming within the disk.
That’s why the COMPASS team used ALMA to search for these forms of methanol in the gas belonging to the planet-forming disks around the 11 nearby low-mass protostars. The observations have also helped assess the general chemical diversity of these disks.
The unexpected discovery of a methanol molecule containing deuterium was made in the planet-forming disk around only one of those 11 stars, namely the young star IRAS 4A2, located about a thousand light-years away in the Perseus Molecular Cloud.
IRAS refers to the Infrared Astronomical Satellite, which was a joint NASA–UK–Netherlands mission launched in 1983 and which first detected this young star as a source of infrared light through the thick gas and dust of the molecular cloud.
The COMPASS team also discovered methanol maser emission from more than half of the 11 protostars, favoring the youngest of the stars. A maser is a microwave version of a laser in the sense that the microwave emission is being stimulated and then amplified, but astrophysical masers occur naturally, often in shock fronts as methanol molecules collide and are excited.
Methanol masers have previously been detected in planet-forming disks around turbulent high-mass protostars, but COMPASS’ observations are the first detection of them around calmer lower-mass protostars.
“The fact that it has now also been found in a low-mass protostar shows that locally extreme physical conditions can prevail there analogously to massive stars and challenges our previous understanding of the formation of sun-like stars,” said Drozdovskaya.
The finding implies that methanol masers are a common product of all planet-forming discs and therefore are produced by processes that are universal in star- and planet-birth, regardless of the protostar’s mass.
For example, thermal bursts from the growing star as it accumulates gas from its surroundings could generate shocks in a planet-forming disk, stimulating maser activity in the abundant methanol.
“Both results underscore how important high-performance spectroscopic measurements like those from COMPASS with ALMA are for detecting rare and previously unknown chemical phenomena,” said Drozdovskaya, referring to both the methanol masers and the deuterium-rich methanol molecules around IRAS 4A2. “They show just how much we still have to learn about the chemical processes in young protostellar systems.”
The new findings have at least begun to answer some questions, such as how the diversity in this ‘chemical starter kit’ varies from star to star, with ALMA detecting some subtle differences, such as variations in the abundance of oxygen- and nitrogen-bearing molecular species among the eleven stars.
However, questions about how the chemistry of young star systems arises and how it influences the evolution of those systems remain unanswered.
For now, the COMPASS team is painstakingly and systematically studying the data on all the different types of molecules detected in their ALMA observations, and preparing follow-up studies with other facilities including the James Webb Space Telescope (JWST).
“The analysis of all the collected data will take several more years,” said Drozdovskaya.
The first results from COMPASS are published in seven papers [1, 2, 3, 4, 5, 6, 7] in the October 2026 issue of the journal Astronomy & Astrophysics.
