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Astron. Astrophys. 333, 1043-1052 (1998)

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One dimensional prominence model

B.S. Nagabhushana

Indian Institute of Astrophysics, Bangalore-560034, India

Received 3 October 1997 / Accepted 6 January 1998

Abstract

Based on reasonable assumptions and mathematical approximations a one dimensional, analytical model for solar quiescent prominences is constructed, which is in both magneto-hydrostatic and thermal equilibrium. Thermal equilibrium here is a balance among thermal conduction, radiation and wave heating. The wave heating [FORMULA] is assumed to be equal to a constant ([FORMULA]) times the product of pressure (p) and density ([FORMULA]). We find the limit on the value of [FORMULA] for existence of prominence type solution. For given values of [FORMULA], temperature at the center of prominence [FORMULA], gas pressure at the center of prominence [FORMULA] and the temperature at the edge of prominence [FORMULA], we found the following limits on the variables for the existence of the equilibrium: (1) the lower limit on the value of gas pressure at the edge of prominence [FORMULA], (2) the upper and lower limits on the length of the magnetic field line from the center to the edge of the prominence and (3) the upper limit [FORMULA] on the value of [FORMULA] where [FORMULA] is the width of the prominence and [FORMULA] is the shear angle.

For specified values of [FORMULA], [FORMULA], [FORMULA], [FORMULA] and for [FORMULA] [FORMULA] [FORMULA] there exist, in general, two types of solutions. In Type 1 solution, equilibrium is nearly isobaric and the magnetic field is strong and nearly horizontal. This type of solution is physically inadmissible when the value of [FORMULA] falls bellow a certain limit defined in the text. Conditions in this solution approach those in a real prominence as [FORMULA] approaches [FORMULA]. In Type 2 solution, there is a large variation of gas pressure from the center to the edge, and the magnetic field is weak and nearly vertical. Conditions in this solution also approach those in a real prominence as [FORMULA] approaches [FORMULA]. The physical characteristics of Type 1 and Type 2 solutions simulate those of 'normal' and 'inverse' prominences respectively as observed by Bommier et al. (1994).

Key words: Sun: prominences – Sun: corona

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© European Southern Observatory (ESO) 1998

Online publication: April 28, 1998

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