Strong Stellar Magnetic Fields May Suppress Powerful Plasma Eruptions, Study Finds

Researchers from the Technion and their European colleagues have presented the first experimental evidence suggesting that powerful magnetic fields surrounding stars can completely prevent Coronal Mass Ejections (CMEs), which are massive eruptions of charged gas and magnetic material from a star's outer atmosphere. This discovery, published in Physical Review Letters, addresses a long-standing astrophysical puzzle: why are these giant eruptions, common on our Sun, rarely observed around other stars?

CMEs play a significant role in stellar evolution, mass loss, and the space environment of orbiting planets. Despite their importance, conclusive evidence for their occurrence around stars other than the Sun has been scarce. To investigate this, the scientists combined astrophysical simulations, advanced plasma laser experiments, and three-dimensional magnetohydrodynamic models.

The laboratory experiments recreated conditions typical of stellar plasma eruptions, examining plasma flow behavior under varying magnetic field strengths. The findings revealed a clear transition: with weaker magnetic fields, plasma flows dispersed freely. However, as the magnetic field strength increased, the flows became unstable, broke into smaller structures, and eventually stopped altogether.

Simulations identified magnetic instabilities, specifically kink instabilities, as the mechanism preventing plasma from escaping the star. The experimental results closely matched astrophysical predictions, indicating that a magnetic field strength of approximately 100 Gauss is sufficient to contain these eruptions and prevent their expulsion into space. The international collaboration included researchers from the Leibniz Institute for Astrophysics Potsdam (AIP) in Germany and Professor Tzvi Fux from the Technion's Physics Department, along with colleagues from École Polytechnique in France.