Hopf bifurcations in coronal loops. II. Nonlinear evolution of instabilities

• Autores: Gómez, D.; Sicardi Schifino, A.; Ferro Fontán, C.
• Año de publicación: 1990
• Idioma: inglés
• Tipo de recurso: artículo
• Fuente: Astrophys. J. 1990;352(1):326-332
• Materia: Hydromagnetics; Sun: chromosphere; Sun: corona
• Institución: Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturales

In a previous paper, we have modeled the coupling between corona and chromosphere and derived a non-linear set of equations, where the global stability properties of the coronal plasma can be studied. The linear stability analysis indicates that the static equilibrium is stable unless the heating rate falls below a certain critical value. In the present paper, we study the nonlinear evolution of our equations both analytically and numerically. Applying a perturbative technique around the critical point, we find that a subcritical Hopf bifurcation takes place. The numerical integration of the equations agrees satisfactorily with the analytical results when they are compared close to the bifurcation. The nonthermal Doppler widths of EUV lines forming in the transition region can be explained by the existence of relatively low amplitude limit cycles.
Fil:Gómez, D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.
Fil:Sicardi Schifino, A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.
Fil:Ferro Fontán, C. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.