Cosmic Rays near Proxima Centauri b
The discovery of a terrestrial planet orbiting Proxima Centauri has led to a lot of papers
discussing the possible conditions on this planet. Since the main factors determining space weather in
the Solar System are the solar wind and cosmic rays (CRs), it seems important to understand what the
parameters of the stellar wind, Galactic and stellar CRs near exoplanets are. Based on the available data,
we present our estimates of the stellar wind velocity and density, the possible CR fluxes and fluences near
Proxima b. We have found that there are virtually no Galactic CRs near the orbit of Proxima b up to
particle energies ∼ 1 TeV due to their modulation by the stellar wind. Nevertheless, more powerful and
frequent flares on Proxima Centauri than those on the Sun can accelerate particles to maximum energies
∼ 3150αβ GeV (α, β < 1). Therefore, the intensity of stellar CRs in the astrosphere may turn out to be
comparable to the intensity of low-energy CRs in the heliosphere.
According to recent observations, relative number of flare stars does not change very much from cool dwarfs to hot A stars. Flare energies are strongly correlated with stellar luminosity and radius. Whence it follows that the typical magnetic field associated with a flare is several tens of gauss and the typical flare loop length-scales are parts of the stellar radius. Flares on O-B stars were not observed, but they are possible, since strong magnetic fields are detected on O-B stars. Therefore, stars of O-M spectral classes are potential sources of cosmic rays. Energy estimates of a magnetic field strength in a tube in photospheres of O-M stars are performed. Basing on their values possible flare energies and numbers of accelerated protons are estimated. The values obtained for the Sun correspond to observations by order of magnitude that justify estimates for other stars. Values of magnetic field strength in a tube differ less than five times for O and M flares (700 and 3500 G), but corresponding flare energies and numbers of accelerated protons for O stars are greater by five orders. Contrary fluencies of stellar protons appear to be five orders less.
A mathematical model is developed for a multichannel sensor unit based on diamond detectors in a device for monitoring the parameters of cosmic ray ﬂ uxes. The output signals from these sensors are modelled as they detect ionizing radiation from outer space in different spacecraft orbits with various levels of solar activity.
The power dependency of cosmic rays energy distribution over a wide energy range shows their degradation origin. Analysis of the cosmic rays spectra in comparison with the typical degradation spectra of cascade processes makes possible to describe the kinetics processes of origin and propagation of cosmic rays, in particular the differential loss energy probabilities, the cascade role, and to estimate the energy and number of primary cosmic rays particles.
The dynamics of a two-component Davydov-Scott (DS) soliton with a small mismatch of the initial location or velocity of the high-frequency (HF) component was investigated within the framework of the Zakharov-type system of two coupled equations for the HF and low-frequency (LF) fields. In this system, the HF field is described by the linear Schrödinger equation with the potential generated by the LF component varying in time and space. The LF component in this system is described by the Korteweg-de Vries equation with a term of quadratic influence of the HF field on the LF field. The frequency of the DS soliton`s component oscillation was found analytically using the balance equation. The perturbed DS soliton was shown to be stable. The analytical results were confirmed by numerical simulations.
Radiation conditions are described for various space regions, radiation-induced effects in spacecraft materials and equipment components are considered and information on theoretical, computational, and experimental methods for studying radiation effects are presented. The peculiarities of radiation effects on nanostructures and some problems related to modeling and radiation testing of such structures are considered.