Speaker
Description
Energetic particles may have contributed to the start of life on Earth and exoplanets. The stellar energetic particle and Galactic cosmic ray fluxes that reached Earth at the time when life is thought to have begun is largely determined by the stellar wind properties. The magnetic field strength and velocity profile of a solar-type star’s wind evolve with time. Therefore, the modulation of Galactic cosmic rays will evolve with stellar age. Generally, young solar-type stars are very magnetically active and drive faster stellar winds.
I will compare the contributions from two distinct populations of energetic particles: stellar energetic particles accelerated by their host stars and Galactic cosmic rays. I will present our recent results simulating the propagation of energetic particles through the astrosphere to the location of Earth as a function of a solar-type star's life. I will focus on the stellar and Galactic cosmic ray fluxes present at the time when life is thought to have begun on Earth (~1 Gyr) and 600Myr which is relevant for the exoplanetary system, HR 2562b orbiting a ~solar-type star. I will show that the Galactic cosmic ray intensities which reached the young Earth would have been greatly reduced in comparison to the present day intensity. At this time, stellar energetic particle fluxes would have been larger than Galactic cosmic rays at low energies. I will show the effect that the Sun being a slow/fast rotator would have had on the energetic particle fluxes reaching the young Earth. Finally, I will discuss the possible chemical signatures that we might expect from energetic particles which may be observable with upcoming missions such as JWST.
| Subcategory | Theoretical Results |
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