Mapping a Molecular Building Block in a Pre-Stellar Core

To probe the chemistry of cold pre-stellar cores, researchers investigated Lynds 1544 and made the first-ever spatially resolved map of methanimine — a simple molecule that may be involved in the formation of amino acids in space — in this environment.

Astrochemistry at Work

Peering across the galaxy, astronomers have discovered a broad and growing array of molecules, revealing the rich chemistry taking place everywhere from molecular clouds to protoplanetary disks. A central question in astrochemistry is where, when, and how molecules form in space, and how molecules might survive the various phases of star formation and be incorporated into newborn planetary systems, where they could play a role in the construction of complex organic molecules necessary for life.

Today’s research article, led by Yuxin Lin (Max Planck Institute for Extraterrestrial Physics), focuses on a molecule called methanimine (CH₂NH). CH₂NH is the simplest molecule in a class of nitrogen-containing compounds called imines, and it’s thought to be an important stepping-stone in the creation of amino acids.

First Spatially Resolved Map

Lin and collaborators searched for CH₂NH within Lynds 1544 (L1544), a pre-stellar core in the nearby Taurus Molecular Cloud. Pre-stellar cores — condensed, gravitationally bound clumps of cold gas within a molecular cloud — represent an early stage in the process of star formation, just before the gas collapses to form a protostar.

L1544 has been the subject of many astrochemical investigations, and previous studies have revealed that it contains a complex, chemically differentiated envelope surrounding a dense core in which many chemical species have frozen out onto dust grains, leaving the gas depleted of these species.

Using the Institute for Radio Astronomy in the Millimetre Range 30-meter radio telescope, Lin’s team mapped the distribution of CH₂NH across L1544. This isn’t the first time that CH₂NH has been detected in a cold pre-stellar core, but it’s the first time that the molecule has been mapped in a spatially resolved way in such an environment. This allows researchers to compare the distribution of CH₂NH to other molecules in the core and build an understanding of the chemistry behind its formation.

The Chemistry of CH₂NH

The new observations show that CH₂NH can be found throughout L1544, with clear spatial trends in the molecule’s abundance: higher near the outer layers of the core, lower near the center. Using chemical models to aid their analysis, Lin’s team showed that the observed distribution suggests formation pathways driven by moderate amounts of ultraviolet radiation.

In the outer layers of the core, where the gas is less dense, ultraviolet light creates reactive chemical species called radicals that can spur the formation of CH₂NH. In the interior of the core, dense gas prevents the incursion of ultraviolet light. This means that few radicals are created that can help form CH₂NH molecules, and the molecules that do form tend to freeze out onto dust grains, disappearing from the gas.

The discovery of CH₂NH throughout L1544 suggests that the precursors to complex organic molecules can form during the cold, calm pre-stellar core phase of star formation, allowing these molecules to be inherited by nascent planetary systems.

Citation

“First Mapping of Prebiotic Molecule CH₂NH in a Prestellar Core,” Yuxin Lin et al 2026 ApJL 996 L32. doi:10.3847/2041-8213/ae2c76