(News & views on the paper by Wen-Bin Song et al.)
A new idea for the heating mechanism of solar transition region
It is widely accepted that the dramatical enhancement of plasma temperature in the solar transition region of only several ten to one hundred kilometers between the solar chromosphere and corona may be caused by some heating mechanisms relevent to the magnetic field in solar atmosphere, but this important question is not successfully answered so far (Fang et al. 2007). One possible mechanism is that the plasma is directly heated by the Joule dissipation of intense and magnetic field-aligned electric currents (see the references of Rabin and Moore 1984; Antiochos and Noci 1986; Roumeliotis 1991), with some special magnetic configuration or condition which not fully argued by the relevant authors. A similar but new idea is recently proposed by Song et al. (2010) based on the magnetic field distributed in the boundaries of a supergranular cell due to the skin effect and parallel (or antiparallel) to the velocity field inside the cell, which is driven by a small- scaled dynamo and supported by a series of observational results. The heating power of the Joule dissipation that deduced from a simplified MHD model is comparable with the radiative loss of the solar chromosphere (Avrett et al. 1981), while, the depth of the skin effect is also comparable with the thickness of the solar transition region.
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Rabin, D. and Moore, R. 1984, ApJ, 285, 359 [ADS]
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Song, W. B., Feng, X. S., and Shen, F. 2010, RAA, 10, 529 [RAA]