Stellar Prominences Ignite Radio Flares express

Original: "Electron Cyclotron Maser Emission from Ejected Stellar Prominences on V374 Peg"
arXiv:2601.03568 · 2026-01-07 · CC BY-SA 4.0 · 1 min
Plasma ejections from a red dwarf's surface generate powerful radio signals, akin to a lighthouse.

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The red dwarf V374 Pegasi is a star one-third the size of the Sun, but with the temperament of a volcano. Every few hours, giant clumps of plasma tear away from its surface, like steam bubbles from a boiling cauldron. These ejections, called prominences, fly off into space and generate bursts of radio waves.

Astronomers have long detected powerful radio signals from this star, resembling lighthouse pulses. It was thought that a special mechanism produces them: electrons spiraling in the magnetic field emit like tiny radio stations. But where the electrons with the right energy came from remained a mystery.

The new study combined a computer model of the star's magnetic field with archival data from radio telescopes. It turned out that the ejected prominences can accelerate electrons to the required speeds. Moreover, the flares should be visible not all the time, but only when the ejection is on a certain side of the star, like a flashlight that shines in only one direction.

Over four years of observations, only four such flares were captured — a rare stroke of luck, given that the star completes a full rotation in 0.44 days.

The match between the model and the actual flares confirms that prominences indeed act as particle accelerators. Now astronomers want to conduct new observations to catch more such events and understand how often they occur on other stars.

Original abstract

as written by the authors arXiv:2601.03568

We investigate a possible origin for bursty radio emission observed on the active M dwarf V374 Peg, combining data-driven magnetic field modelling with archival radio light curves. We examine whether stellar prominence ejection can plausibly account for the observed radio bursts that have been attributed to electron cyclotron maser (ECM) emission. Our analysis shows that ejected prominences can produce the required energy range to drive the emission, and that modelled ECM visibility exhibits a rotational phase dependence consistent with the limited observational data (four observed bursts). The results support prominence ejection as a viable mechanism for ECM generation on V374 Peg and motivate further observational campaigns to constrain this process.

V374 Pegasi spins so fast that its day lasts less than eleven hours — during which the star manages to show all its sides.

Scientists
Subrahmanyan ChandrasekharEnrico FermiMichael FaradayHendrik LorentzAugustin-Louis CauchyChristiaan Huygens
Concepts
coronal mass ejection neutron star light emission solar eruption millimeter emission stellar flares pulsar fast radio burst solar magnetic phenomena energy release radio pulsar prominence magnetar Gamma radiation electromagnetic radiation ejecta black hole outburst jet outburst flare outflow