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

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 is assumed to be equal to a constant () times the product of pressure (p) and density (). We find the limit on the value of for existence of prominence type solution. For given values of , temperature at the center of prominence , gas pressure at the center of prominence and the temperature at the edge of prominence , 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 , (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 on the value of where is the width of the prominence and is the shear angle.

For specified values of , , , and for 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 falls bellow a certain limit defined in the text. Conditions in this solution approach those in a real prominence as approaches . 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 approaches . 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

Contents

• 1. Introduction
• 2. Basic assumptions and the equations describing the structure
• 3. Method of integration
  • 3.1. Conditions at the center of the prominence
  • 3.2. Integration for
  • 3.3. Integration for and for
  • 3.4. Specifying the boundary conditions
• 4. Condition for the existence of solution
• 5. The nature of solution and comparison with observations
  • 5.1. Study of variation of and with respect to the variation of for a given value of
  • 5.2. Study of variation of the magnetic field line length(s) with respect to the variation of for a given value of
  • 5.3. Nature of the solution for various values of , , and
  • 5.4. Comparison with observations
• 6. Conclusions and discussion
• Acknowledgements
• References

© European Southern Observatory (ESO) 1998

Online publication: April 28, 1998

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