Soon the Helioseismic & Magnetic Imager (HMI) aboard the Solar Dynamics Observer (SDO) will provide the first high-cadence, high-resolution imaged vector magnetograms from space. Collection of these data represent an unprecedented opportunity to study solar flares and coronal mass ejections, i.e., the violent solar explosions that produce geoeffective space weather disturbances. The mechanism(s) initiating and driving these solar eruptions are not completely understood, but coronal structure, flux-emergence, and plasma flows certainly play important roles. I will describe a new technique that combines plasma physics, image processing and statistics to estimate photospheric plasma velocities from a sequence of vector magnetograms. This method combined with SDO/HMI data will resolve open questions about the development of complexity in the corona and the energization and initiation of solar flares and coronal mass ejections.
We introduce the concept of magnetic reconnection and discuss in more detail a specific northward interplanetary magnetic field (IMF) reconnection event at the Earth's magnetopause. We present a technique that exploits multiple spacecraft data to determine the impact parameters of the most general form of magnetic reconnection at the magnetopause. The method consists of a superposed epoch of multiple spacecraft magnetometer measurements that yields the instantaneous magnetic spatial gradients near a magnetopause reconnection site. The gradients establish the instantaneous positions of the spacecraft relative to the reconnection site. Application of the method to Cluster data known to lie in the vicinity of a northward IMF reconnection site establishes a field topology and particle flows consistent with singular field line reconnection and a normal magnetic field component of 20 nT. The corresponding current structure consists of a 130 km sheet possibly embedding a thinner, bifurcated sheet. The observed singular field line, or guide field, exists only within the magnetopause. Through comparison to a global MHD simulation, we elicit possible causes of this kind of guide field.
Shocks are ubiquitous in both Heliospheric and Astrophysical contexts. Corotating Interaction Regions (CIRs), planetary bow shocks, and the heliospheric termination and bow shocks are just a few examples in the heliosphere. In astrophysics, shocks are seen in the expanding blast ring from Supernova Remnants (SNRs) and the relativistic jets associated with gamma-ray bursts (GRBs) and Active Galactic Nuclei (AGNs). The nature of the particle acceleration process at shocks combined with their ubiquity suggests that the robust spectrum of Cosmic Rays seen at Earth is likely the result of shock acceleration in a variety of Heliospheric and Astrophysical environments. We have developed a Monte Carlo simulation of the acceleration process that provides for direct comparison with in-situ observations inside the Heliosphere but also has the capability to model the acceleration process in Astrophysical contexts. The former, where results can be directly compared to observations, is an ideal test of the simulation. This allows us to probe the important physics of the acceleration process and incorporate it into the simulation constantly improving our understanding of the acceleration process in shocks. The latter is used to probe dependence of accelerated particle distribution in these relativistic astrophysical shocks on the physical parameters of the shock environment. It is found that relativistic shocks have a wide variety of possible accelerated distributions depending critically on 3 parameters: the speed of the shock in the deHoffman-Teller Frame, the magnitude of the turbulence present, and the microphysics of that turbulence. We conduct a robust exploration of the parameter space for these types of shocks finding that accelerated particle distributions in relativistic shocks can definitely NOT be described by the canonical -2.23 power-law index found in parallel ultra-relativistic scenarios. This has implications for those astrophysicists attempting to infer accelerated particle distributions at astrophysical shocks.