Trappist 1 Exposed To Heavy Bombardment Of Charged Particles

In a new paper in The Astrophysical Journal, Harvard-Smithsonian Center For Astrophysics (CfA) astronomers Federico Fraschetti, Jeremy Drake, Julian Alvardo-Gomez, Sofia Moschou, and Cecilia Garraffo and a colleague carry out theoretical simulations of the effects of high-energy protons from a stellar wind on nearby exoplanets. These particles are produced by stellar flares or by shock waves driven by magnetic events in the stellar corona. Measurements of solar eruptive events provide the scientists with a basis for their simulations. The astronomers calculate the first realistic simulation of the propagation of energetic particles through the turbulent magnetic field environment of an M dwarf star and its wind, and they tailored the details to the TRAPPIST-1 system. They find that particles are trapped within the star’s magnetic field and are directed into two polar streams focused onto the planets’ orbital plane – independent of many of the details. The scientists conclude that the innermost putative habitable planet in the system, TRAPPIST-1e, is bombarded by a proton flux up to a million times larger than that experienced by present-day Earth. Nevertheless, there are many variables at play, for example, the angle between the magnetic field and the rotation axis of the star, and consequently, a large uncertainty remains in how these effects actually manifest in individual situations. Reference(s): “Stellar Energetic Particles in the Magnetically Turbulent Habitable Zones of TRAPPIST-1-like Planetary Systems” by F. Fraschetti, J. J. Drake, J. D. Alvarado-Gomez, S. P. Moschou, C. Garraffo, and O. Cohen, 11 February 2019, arXiv.DOI: 10.48550/arXiv.1902.03732