Bulletin of the American Physical Society
2005 47th Annual Meeting of the Division of Plasma Physics
Monday–Friday, October 24–28, 2005; Denver, Colorado
Session KZ2: Mini-conference on Dynamics of Magnetic Flux Tubes in Space and Laboratory Plasmas I |
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Chair: Michael Hesse, NASA Goddard Room: Adam's Mark Hotel Governor's Square 14 |
Wednesday, October 26, 2005 9:30AM - 10:00AM |
KZ2.00001: Reconnection of Magnetic Flux Tubes Mark Linton Magnetic reconnection plays an important role in energy release in solar, magnetospheric, and laboratory plasmas. However, this reconnection is usually three dimensional, and so quite difficult both to study and to conceptualize. Dividing three dimensional magnetic fields up into flux tubes and studying how individual pairs of flux tubes reconnect provides a way to make the reconnection dynamics more tractable. We will present a review of the current understanding, both from theory and from simulation, of flux tube reconnection. We will also present a brief introduction of the implications this reconnection has for understanding flux tube dynamics in space and laboratory plasmas. [Preview Abstract] |
Wednesday, October 26, 2005 10:00AM - 10:30AM |
KZ2.00002: Magnetic Flux Tubes in the Solar Interior William Abbett I will present an overview of recent efforts to understand the life-cycle of active region magnetic fields --- from their formation deep in the solar interior to their ultimate decay observed at the visible surface. A critical component of these efforts is to understand the dynamic connection between magnetic fields (at both large and small scales) observed threading the solar atmosphere and their sub-surface counterparts. I will focus on the following questions: How well do we understand the physics of flux emergence through the solar convection zone --- from the formation of magnetic flux tubes to their full or partial emergence through the photosphere? Can numerical simulations of active region magnetic fields explain the observed evolution and decay of surface fields obtained from vector magnetograms? [Preview Abstract] |
Wednesday, October 26, 2005 10:30AM - 10:45AM |
KZ2.00003: Magnetic Helicity and Flux Tube Dynamics in the Solar Convection Zone Dibyendu Nandy, Richard Canfield Magnetic helicity, a conserved topological parameter in ideal MHD systems -- conditions close to which are realized in the solar plasma, is intimately connected to the creation and subsequent dynamics of magnetic flux tubes in the solar interior. It can therefore be used as a tool to probe such dynamics. Here we discuss how observations of magnetic helicity, manifested as the twist and writhe of solar active regions, can constrain the dynamics of flux tubes through the solar convection zone. [Preview Abstract] |
Wednesday, October 26, 2005 10:45AM - 11:15AM |
KZ2.00004: Twisted magnetic flux ropes: A breeding ground for CMEs? Sarah Gibson The state of coronal magnetic fields prior to a coronal mass ejection (CME) is critical to the physical mechanisms that drive eruptions. It is generally accepted that the energy that drives the CME is magnetic in origin. Sheared coronal fields can store energy which ultimately will be released in the eruption of the CME. We explore the possibility of a specific magnetic pre-CME configuration, that of a magnetic flux rope of field lines that twist about an axial field line. We find the concept of the flux rope both theoretically and observationally compelling. From a theoretical perspective, the flux rope may represent a minimum energy configuration that conserves magnetic helicity, and as such be a common equilibrium state in the corona capable of storing enough magnetic energy to drive a CME. When some helicity or twist threshold is crossed, the equilibrium is lost, and the energy is released in the CME. From an observational point of view, the flux rope model predicts specific coronal observables, for example X-ray sigmoids and white light cavities. Therefore, studying the observed evolution of such quiescent coronal structures prior to the CME gives us crucial insight into the physics of coronal storage and release of energy. [Preview Abstract] |
Wednesday, October 26, 2005 11:15AM - 11:30AM |
KZ2.00005: The Formation of 3D Flux Ropes in Coronal Mass Ejections Spiro Antiochos, Ben Lynch, Richard DeVore It is widely believed that a coronal mass ejection (CME) represents the explosive ejection of a magnetic flux rope from deep in the Sun's corona out to the Heliosphere. A critical issue for understanding the initiation and structure of CMEs is the formation of the ejected flux rope. In one class of models the flux rope forms in the corona well before the ejection, whereas in the ``breakout'' model the flux rope forms only as a result of the ejection. We present the latest 3D simulations of the breakout model, which demonstrate the formation process, in detail. We argue that the flare reconnection {\bf following} a CME, is the only likely mechanism for creating a large, coherent flux rope in the solar atmosphere. \\ This work was supported, in part, by ONR and NASA. [Preview Abstract] |
Wednesday, October 26, 2005 11:30AM - 12:00PM |
KZ2.00006: Magnetic Reconnection in the Solar Wind and the Evolution of Magnetic Flux Tubes in the Heliosphere John Gosling To zeroth order, the heliospheric magnetic field, HMF, is adequately described by Parker’s Archimedean spiral model of field lines open to the outer boundary of the heliosphere. However, there is ample evidence that the HMF is considerably more complex than was first described by Parker and that the field topology often evolves with distance from the Sun. Processes contributing to this evolution and complexity include, at the very least, differential solar rotation, the insertion of closed magnetic fields into the solar wind associated with coronal mass ejections, foot point motions associated with solar convection, solar wind turbulence, solar wind stream interactions and magnetic reconnection. Here we discuss magnetic flux tube evolution in the heliosphere with an emphasis on the recently recognized phenomenon of local, quasi-stationary reconnection in the solar wind far from the Sun. [Preview Abstract] |
Wednesday, October 26, 2005 12:00PM - 12:30PM |
KZ2.00007: Flux Transfer Events: Flux Ropes at Earth's Magnetopause Joachim Raeder We give a brief introduction into the observational evidence for flux ropes at Earth's magnetopause, also known as Flux Transfer Events (FTEs). We will then discuss global magnetosphere simulations that show how FTEs form and what parameters the formation process depends on. [Preview Abstract] |
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