ИСТИНА

Quasi-stationary structures arising in the interplanetary medium near 1 AU are studied, which represent magnetic traps for energetic electrons emitted from the magnetosphere of Jupiter. When such a trap passes by Earth, enhanced electron fluxes are observed. The flux peaks are not high; they are only visible clearly at low background, i.e., at low solar activity. We compare electron flux observations during subsequent solar activity minima. A particularly long series was observed during the last minimum in 2007-2009 with an average period of about 26 days, instead of 27.3 days expected - the synodic period of the Earth. During other solar activity minima the period also differs from it by 1-2 days suggesting the existence of a complicated structure consisting of magnetic traps which allows Jovian electrons to arrive at Earth irrespective of the relative position of Jupiter and Earth. The size of traps, their longitudinal extension and the lifetime of electrons is studied together with the magnetic field and its variability. In numerical simulations assuming perfect co-rotation and Jupiter as a moving source in the co-rotating frame a combined effect of the CIR and magnetic connection is obtained and fitted to the observations.