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Astron. Astrophys. 350, 1035-1039 (1999)

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The temperature and density structure in the closed field regions of the solar corona

J.F. McKenzie, G.V. Sukhorukova and W.I. Axford

Max-Planck-Institut für Aeronomie, Postfach 20, 37189 Katlenburg-Lindau, Germany

Received 2 March 1999 / Accepted 23 July 1999


In this paper we study the temperature and density structure in the closed field region of the solar corona using a dipole plus current sheet model to simulate the global solar magnetic field and a heating function of the same type used in models of the fast wind. The heat equation, describing the redistributing effects of heat conduction on the heat input in the presence of radiative losses, is solved simultaneously with hydrostatic pressure balance. At the base we prescribe the temperature and assume that the heat flux is zero there. We also insist that the heat flux is zero at the equator. This ensures that whatever heat has been added is radiated away. From the mathematical viewpoint this additional requirement sets up an eigenvalue problem which implies that the density at the base must be chosen in just the right way to fulfill the condition of zero heat flux at the equator. Thus our model not only provides the temperature and density structure in the closed regions of a global solar magnetic field appropriate to solar minimum but also predicts the latitudinal variation of the base density whose characteristic value is determined by the ratio of the amplitudes of the heating to the cooling. However it should be stressed that this last prediction represents, at best, an approximation to the real stale of affairs which is more complex and involves the connection of the coronal field lines to the magnetic funnels of the chromospheric network.

Key words: Sun: atmosphere – Sun: corona – Sun: magnetic fields

Send offprint requests to: J.F. McKenzie

© European Southern Observatory (ESO) 1999

Online publication: October 14, 1999