1.2.11. The dependence of Aon Ek from data of solar CR propagation

The numerous data on the time dependence of the solar CR (see in Dorman and Miroshnichenko, M1968; Dorman, M1978; Miroshnichenko, M2001) show that the transport scattering path A ^ EjĀ°'8"10 in the high energy range (> several hundreds of MeV), whereas the dependence of A on Ek approaches the form A ~ const with decreasing energy. The Gorchakov et al. (1975) analysis of the observations of the time dependence of the flux and anisotropy of solar CR from some chromospheric flares has shown that in this case the protons exhibit a trend of the increase in A with decreasing Ek at Ek < 10^30 MeV (see Fig. 1.2.4) in an agreement with Fig. 1.2.3.

Fig. 1.2.4. The behaviour of A as a function of Ek for solar CR from the flares of November 18, 1968, September 1, 1971 and September 7, 1973. According to Gorchakov et al. (1975).

Some qualitative difference in A between Fig. 1.2.3 and Fig. 1.2.4 is because A in the first case is the effective value for galactic CR averaged over the entire modulation region, whereas A for solar CR reflects the local conditions in a near-Sun region of size of only several AU.

1.2.12. The features of the solar modulation of the CR spectrum and the measurements of the radial gradient

The numerous measurements of the radial CR gradient have given values several times smaller than those predicted by the modulation theory in terms of the spherically symmetrical model. This seems to place doubt on the correctness of the interpretation of the features of the solar modulation of the CR spectrum presented above. As was shown in Alania et al. (1977), however, the inclusion of the helio-latitude dependence of the solar wind parameters completely eliminates this difficulty (the CR penetrate through the high helio-latitude region and leak convectively near the helio-equator resulting in a pronounced decrease of the radial gradient compared with the value expected in terms of the spherically symmetrical model, which agrees with the experimental data). In this case, according to Alania et al. (1977), the spectrum modulation mode proves to be practically the same as in the spherically-symmetrical model.

1.2.13. The nature of the CR in energy intervals 3 - 5

It follows from the above analysis that the data on the chemical and isotopic composition, the energy spectrum, and the solar modulation prove without any doubt the galactic origin of interval 3 (30 MeV^300 GeV). The problem is, however, much more complicated for intervals 4 and 5 and requires a special and comprehensive analysis including the diversity of the data on the chemical composition, the solar modulation, the temporal variations at different energies, the data on CR generation on the Sun, Jupiter, and in interplanetary space, and the indirect data on the possible existence of such particles in interstellar space (see in Dorman, 1977a,b). However, the result obtained above that A increases rapidly with decreasing Ek is indicative of the possibility of penetration of the particles of such low energies from the Galaxy to the inside of the Heliosphere.

Was this article helpful?

0 0

Post a comment