TWISTED FLUX TUBE EMERGENCE FROM THE CONVECTION ZONE TO THE CORONA. II. LATER STATES
- Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, N-0315 Oslo (Norway)
Three-dimensional numerical simulations of magnetic flux emergence are carried out in a computational domain spanning the upper layers of the convection zone to the lower corona. We use the Oslo Staggered Code to solve the full magnetohydrodynamic equations with non-gray and non-local thermodynamic equilibrium radiative transfer and thermal conduction along the magnetic field lines. In this paper, we concentrate on the later stages of the simulations and study the evolution of the structure of the rising flux in the upper chromosphere and corona, the interaction between the emerging flux and the weak coronal magnetic field initially present, and the associated dynamics. The flux tube injected at the bottom boundary rises to the photosphere where it largely remains. However, some parts of the flux tube become unstable and expand in patches into the upper chromosphere. The flux rapidly expands toward the corona, pushing the coronal and transition region material aside, and lifting and maintaining the transition region at heights greater than 5 Mm above the photosphere for extensive periods of time. The pre-existing magnetic field in the corona and transition region is perturbed by the incoming flux and reoriented by a series of high Joule heating events. Low-density structures form in the corona, while at later times a high-density filamentary structure appears in the lower part of the expanding flux. The dynamics of these and other structures is discussed. While Joule heating due to the expanding flux is episodic, it increases in relative strength as fresh magnetic field rises and becomes energetically important in the upper chromosphere and corona at later times. Chromospheric, transition region, and coronal lines are computed and their response to the perturbation caused by the expanding emerging flux is discussed.
- OSTI ID:
- 21333861
- Journal Information:
- Astrophysical Journal, Vol. 702, Issue 1; Other Information: DOI: 10.1088/0004-637X/702/1/129; Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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