FORMATION, LEVITATION, AND STABILITY OF PROMINENCES IN THE MAGNETIZED SOLAR ATMOSPHERE

We simulate the dynamic formation and ultimate stable support, against gravity, of a Kippenhahn-Schluter prominence at the apex of a magnetic arcade. As a preparatory step, we also elucidate the thermal structure of the magnetized solar atmosphere, which consists of short, cool, chromospheric-like loops at low altitude and long, hot-apex, coronal loops at high altitude. This investigation is completed in three steps: the creation of a background magnetothermal equilibrium, the initiation and nonlinear formation of a massive siphon condensation with attendant magnetic field deformation, and the verification of translational stability. This is all accomplished with a model based on the two-dimensional magnetohydrodynamic equations, which also includes gravity, compressible flows, heating, radiation, anisotropic thermal conduction, and coupling to a deep chromosphere. The equilibrium solar atmosphere evolves to a complex structure even in the absence of a prominence. Cool and dense material fills the low-lying magnetic loops, producing a corrugated transition region between the hot and diffuse corona and the chromosphere. Prominences subsequently form in response to a large isobaric enhancement of the density at the apex of a coronal loop. Material siphons from the chromosphere as the result of a pressure depression driven by enhanced radiation, and forms a spatially localized, high-density, low-temperature prominence. The gravitational force acting on the condensation mass distorts the local magnetic field, thereby producing a magnetic sling of normal polarity, which supports the prominence. Prominences in simple arcades, for which the preprominence magnetic field has significant negative curvature at the apex, are found to be unstable to a lateral displacement: they eventually fall down the magnetic field onto the chromosphere. In more complex arcades, in which the initial magnetic field is nearly horizontal or has only small negative curvature, prominences are both dynamically and thermally stable.