Charting nearby stellar systems: The intensity of Galactic cosmic rays for a sample of solar-type stars

Abstract

Cosmic rays can penetrate planetary atmospheres driving the formation of prebiotic molecules, which are important for the origin of life. We calculate the Galactic cosmic ray fluxes in the habitable zone of five nearby, well-studied solar-type stars and at the orbits of 2 known exoplanets. We model the propagation of Galactic cosmic rays through the stellar winds using a combined 1.5D stellar wind and 1D cosmic ray transport model. We find that the habitable zone of 61 Cyg A has comparable Galactic cosmic ray fluxes to present-day Earth values. For the other four systems ($\epsilon$ Eri, $\epsilon$ Ind, $\xi$ Boo B and ${\pi }^1$ UMa), the fluxes are orders of magnitude smaller than Earth values. Thus, it is unlikely that any as-of-yet undetected Earth-like planets in their habitable zones would receive a higher radiation dose than is received on Earth. $\epsilon$Indb, a Jupiter-like planet orbiting at $\sim$11au, receives higher Galactic cosmic ray fluxes than Earth. We find the suppression of Galactic cosmic rays is influenced by whether diffusion or advection dominates at GeV energies and at distances where the wind has reached its' terminal velocity. For advectively-dominated winds ($\sim$younger systems), varying the astrospheric size influences the suppression significantly. For diffusion-dominated systems ($\sim$older systems) the astrospheric size, and therefore knowledge of the ISM properties, are not very important. This reduces the Galactic cosmic ray flux uncertainties in the habitable zone for diffusion-dominated systems. Whether a system is advection- or diffusion-dominated can be determined from the stellar wind properties.

10 pages, 4 figures, accepted for publication in MNRAS

References in corpus (20)

• The James Webb Space Telescope
• Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics
• Habitable Zones Around Main-Sequence Stars: Dependence on Planetary Mass
• Stellar magnetism: empirical trends with age and rotation
• Stellar Winds on the Main-Sequence II: the Evolution of Rotation and Winds
• The Extrasolar Planet epsilon Eridani b - Orbit and Mass
• The evolution of the solar wind
• Theoretical mass loss rates of cool main-sequence stars
• Detection of the nearest Jupiter analog in radial velocity and astrometry data
• The ionising effect of low energy cosmic rays from a class II object on its protoplanetary disk
• On the Diversity of M-Star Astrospheres and the Role of Galactic Cosmic Rays Within
• Stellar versus Galactic: The intensity of cosmic rays at the evolving Earth and young exoplanets around Sun-like stars
• Stellar Proton Event-induced surface radiation dose as a constraint on the habitability of terrestrial exoplanets
• Ions in the Thermosphere of Exoplanets: Observable Constraints Revealed by Innovative Laboratory Experiments
• Lightning and charge processes in brown dwarf and exoplanet atmospheres
• The Earth-like Galactic cosmic ray intensity in the habitable zone of the M dwarf GJ 436
• On the Fast Magnetic Rotator Regime of Stellar Winds
• Polarized radiation and the Emergence of Biological Homochirality on Earth and Beyond
• Stellar cosmic rays as an important source of ionisation in protoplanetary disks: a disk mass dependent process
• Modeling Solar Proton Event-induced Martian Surface Radiation Dose

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• The energetic particle environment of a GJ 436 b-like planet
• The strong suppression of Galactic cosmic rays reaching AU Mic b, c and Prox Cen b
• Galactic cosmic ray propagation through M dwarf planetary systems
• Modeling the astrosphere of LHS~1140