Posted by Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) are uncovering how organic chemistry develops around young stars and may eventually supply material to forming planetary systems.
The results come from the COMPASS Large Program – Complex Organic Molecules in Protostars with ALMA Spectral Surveys – an international project studying 11 nearby, young Sun-like protostars. More than 100 hours of ALMA observing time were used to compare their chemistry across different environments and stages of stellar evolution. ALMA detects molecules through their characteristic spectral fingerprints. By combining signals from many antennas, the observatory can identify extremely faint molecular emission and map where different compounds occur on scales comparable to the Solar System.
The first COMPASS results, presented in seven papers in Astronomy & Astrophysics, show that even very young stellar systems contain unexpectedly complex chemistry. Several studies focus on methanol, a simple alcohol that is important in chemical pathways leading to larger organic molecules. One result suggests that methanol maser emission is much more common around low-mass protostars than previously recognized. Masers form when molecules under particular physical conditions amplify radiation at specific radio frequencies. COMPASS detected methanol masers in more than half of the systems studied, indicating that this phenomenon may be widespread during early stellar evolution but difficult to detect without highly sensitive observations.
Another study reported the first detection in space of fully deuterated methanol, CD₃OD, in which all four hydrogen atoms are replaced by deuterium, a heavier isotope of hydrogen. The molecule was detected around the protostar IRAS 4A2 in the Perseus molecular cloud, roughly 1,000 light-years from Earth. Different isotopic forms of methanol provide clues about the temperatures and chemical conditions in which molecules formed. By comparing these signatures across multiple protostars, researchers hope to determine whether chemical differences are inherited from their birth environments or develop later as the systems evolve.
For astrobiology, this matters because the chemistry surrounding young stars represents an early stage in the journey from interstellar material to planet-forming disks. COMPASS may therefore help reveal how organic ingredients capable of contributing to prebiotic chemistry become incorporated into emerging planetary systems.
For more details, read the full article by ALMA.
