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On the temperature of the solar corona


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Abstract

It has long been considered that the high temperature of the solar corona, inferred from the presence of highly ionized atoms such as FeXIV, is caused by various heat transfer processes from the photosphere. In this paper, it is suggested that the neutral hydrogen layer, containing Fe atoms, of the corona, are ionized by the impact of energetic current carrying electrons along loops of magnetic field lines. It is suggested that current-carrying electrons are accelerated by the double layer; the corona consists of a large number of magnetic loops. It is shown that the current of intensity of about 1μA/ cm2, consisting of 10 Kev electrons accelerated by the double layer, could provide the ionization rate of 1.8 x 104/cm3 in the corona along the loops. Thus, the corona could not be in a thermal equilibrium, so that the temperature of the corona may not be inferred from what the ionization potential of highly ionized atoms suggests. It is shown also that a dynamo process of the photosphere can generate the need field-aligned currents. Further, the above estimated ionization rate can supply the solar wind.

Keywords

solar corona, ionization rate, energetic electrons double layer

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