Stellar eruptions in the laboratory: First experimental evidence for their suppression in strong magnetic fields

A team of astrophysicists and plasma physicists has provided the first experimental evidence that strong magnetic fields surrounding active stars can completely suppress coronal mass ejections (CMEs). The study, published in Physical Review Letters, combines astrophysical simulations, high-energy laser-plasma experiments, and advanced three-dimensional numerical plasma modeling. The results show that strong magnetic fields can confine CMEs before they escape into space. The experiments were conducted in a laboratory setup at the Ecole Polytechnique, where the team used laser-driven plasma flows to mimic the core of stellar CMEs. When exposed to relatively weak ambient magnetic fields, the plasma propagated freely, but stronger magnetic fields caused the flow to fragment, become unstable, and ultimately stop. The unique combination of theory, laboratory tests, and numerical simulations provides the first experimental evidence supporting a long-standing prediction that stellar magnetic fields can confine these large-scale eruptions.

• The study was conducted by an international team of researchers, including Julián D. Alvarado-Gomez and Julien Fuchs.
• The experiments used laser-driven plasma flows to mimic the core of stellar CMEs.
• The results show that strong magnetic fields can suppress CMEs, preventing them from escaping into space.
• The findings suggest that CMEs are rare around stars because many eruptions may be trapped by the surrounding magnetic fields.
• The kink instability in the plasma flow was identified as the mechanism responsible for disrupting the eruption.
• The experiments demonstrated that when magnetic fields are strong enough, the plasma flow becomes unstable and stops entirely.

The findings have implications for exoplanets, as CMEs are extreme forms of stellar space weather. If many CMEs are magnetically suppressed, some exoplanets may be exposed to a less hostile space environment, improving their prospects for retaining atmospheres over billions of years. The study highlights the role of magnetic fields in shaping stellar evolution and space weather, offering insights into why CMEs are rare around stars other than the sun.

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