Magnetic interactions found between Proxima Centauri and its planets

Star system: Alpha Centauri | Distance from the Sun: 4.4 light years

Proxima Centauri, the closest star to the Sun, hosts at least two planets: Proxima b and Proxima d. Using high-resolution optical observations, astronomers searched for signs of magnetic interactions between the star and its planets. They measured the star’s rotation period as about 85 days and found that Proxima Centauri experiences frequent flares, with about 5 percent of the observing time showing flare activity. Statistical analysis revealed that many of these flares are phase-locked to the orbit of the inner planet, Proxima d, suggesting a direct magnetic connection.

By modeling the interaction, the team estimated that Proxima d could have a polar magnetic field of about minus 16 gauss, with possible values ranging from 3 to 280 gauss depending on the planet’s size and the star’s magnetic field configuration. This is the first such estimate for a terrestrial exoplanet. For the outer planet, Proxima b, evidence for star-planet interaction comes from changes in flare intensity rather than timing. Analysis of chromospheric emission lines showed periodic signals matching both planets’ orbits and the star’s rotation, indicating that both planets influence the star’s magnetic activity.

These findings provide strong evidence that terrestrial exoplanets can interact magnetically with their host stars, affecting stellar activity and possibly planetary environments. The results open new possibilities for studying exoplanetary magnetism and its effects on habitability.

Key findings
- Proxima Centauri’s flares are often phase-locked to Proxima d’s orbit, indicating magnetic interaction.
- Proxima d’s polar magnetic field is estimated at about minus 16 gauss.
- Proxima b influences the intensity of stellar flares.
- Chromospheric emission lines show periodicities matching planetary orbits and stellar rotation.
- Both planets show evidence of magnetic interaction with their host star.

Scientific study

Star-planet interaction in the Proxima system (external link)