Abstract
Ionization plays a key role in the formation of stars, planets and planetary atmospheres. Cosmic rays (CR) are the main source of ionization, therefore it is important to estimate fluxes of galactic and stellar cosmic rays (GCR and SCR) for different stages of evolution of stars and planetary systems. Radiation conditions on exoplanets might be important for the origin and development of life. We present a review of the current state of knowledge of astrospheres and their interactions with GCR and SCR. We pay special attention to estimates of radiation conditions near exoplanets recently discovered in a habitable zone of their hosting stars.
Highlights
The cosmic-rays dominate in the ionization and heating of the interstellar medium (ISM)
The spectra of both proton and electron Cosmic rays (CR) in the local interstellar medium (ISM) at least down to particle energy of a few MeVs are known with some confidence, thanks to the recent data collected by the Voyager probe at large distances from the Sun [2]
Authors of [8] modeled ionization of stellar energetic particles in protoplanetary disks around T Tauri stars using a particle energy distribution derived from solar flare observations and an enhanced stellar particle flux proposed for T Tauri stars
Summary
The cosmic-rays dominate in the ionization and heating of the interstellar medium (ISM). The spectra of both proton and electron CRs in the local interstellar medium (ISM) at least down to particle energy of a few MeVs are known with some confidence, thanks to the recent data collected by the Voyager probe at large distances from the Sun [2]. The intensity of CRs in the local ISM as revealed by Voyager measurements is too weak to explain the level of ionization rate observed in clouds Possible solutions to this problem include the presence of another source of ionization or a non-uniform intensity of low energy CRs throughout the Galaxy [5]. Authors of [8] modeled ionization of stellar energetic particles in protoplanetary disks around T Tauri stars using a particle energy distribution derived from solar flare observations and an enhanced stellar particle flux proposed for T Tauri stars. They have shown that stellar energetic particles can be an important ionization agent for disk chemistry
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