April 16, 2010, 12:00 pm - 1:00 pm

April 16, 2010, 12:00 pm - 1:00 pm

Science highlights of studies using multi-point magnetic field measurements from Space Technology 5 mission

Guan Le (GSFC, Space Weather Laboratory)

Space Technology 5 (ST-5) is a three micro-satellite constellation deployed into a 300 x 4500 km, dawn-dusk, sun-synchronous polar orbit from March 22 to June 21, 2006, for technology validations. During its short 3-month mission, the constellation returned high quality magnetic field data as they flew in formation and made simultaneous multi-point measurements of the magnetic field through the Earth’s dynamic auroral field-aligned current region. In this talk, we will present the science highlights of studies using multi-point magnetic field data from ST-5 mission. These studies include: first direct measurements of field-aligned current density using two point magnetic gradiometry, first determination of motion and temporal variability of field-aligned currents on scales of 7 – 700 sec and 50 – 5500 km, quantifying the imbalance of Region 1 and 2 field-aligned currents and the cross-polar cap Pedersen currents, observations of azimuthal characteristics of field-line resonances at low altitudes, as well as measurements of gradients of the Earth’s crustal magnetic field.

Collisionless Magnetic Reconnection

Michael Hesse (GSFC, Space Weather Laboratory)

Resistive Magnetohydrodynamic Simulations of Relativistic Magnetic Reconnection

Seiji Zenitani (GSFC, Space Weather Laboratory)

Magnetic reconnection attracts growing attentions not only in heliophysics but also in relativistic astrophysics. In the past decade, relativistic magnetic reconnection have been actively studied by modern simulations by using kinetic and two-fluid models. However, although there is a great demand for relativistic magnetohydrodynamic (RMHD) model, only one reconnection work was done because of the numerically difficulty. In this work, applying recent progress in numerical schemes, we carry out RRMHD simulations of relativistic magnetic reconnection. The system exhibits a familiar reconnection picture, a Petschek-type outflow exhaust with a big plasmoid. Thanks to the shock-capturing code and our exotic parameters, we find a variety of new structures in and around the plasmoid. We will discuss nonlinear structures of RRMHD reconnection, relevance to the theories, and perspective for future relativistic reconnection research.