Astronomers detect ambipolar diffusion in prestellar core, a key to star birth

Astronomers have detected ambipolar diffusion inside a prestellar core for the first time, observing a process that may allow gravity to overcome magnetic resistance and trigger star formation. The study, led by researchers at Kyushu University and the Max Planck Institute for Extraterrestrial Physics, was published in Astronomy & Astrophysics. Using radio observations of L1544, a dense prestellar core in the Taurus molecular cloud, the team identified molecular drift signaling that magnetic fields are weakening in the core's interior. Prestellar cores are cold, compact pockets of gas and dust that have not yet formed a protostar. In these objects, gravity pulls material inward while magnetic fields and gas motions can resist collapse. The new detection shows ambipolar diffusion-where neutral particles drift relative to charged particles tied to magnetic field lines-is active in L1544, providing a pathway for the field to weaken and gravity to take hold. First author Doris Arzoumanian, associate professor at Kyushu University's Institute for Advanced Study, said prestellar cores are dense, cold environments where complex chemistry produces prebiotic molecule precursors. The findings clarify a long-debated mechanism in star formation: how magnetic support yields to gravitational collapse.