AGU: New Observations & Details on Heliosphere & Aurora
The following highlights summarize research papers that have been recently published in Geophysical Research Letters (GRL).
OBSERVATIONS IMPROVE UNDERSTANDING OF THE HELIOSPHERE
The outer regions of the heliosphere, a giant bubble around the solar system created by solar wind, are difficult to study directly. The Interstellar Boundary Explorer (IBEX) mission, which maps emission of energetic neutral atoms from the boundary between the heliosphere and the interstellar medium, has greatly contributed to understanding of the heliosphere and even discovered some unexpected features. In particular, IBEX maps show a strange “ribbon” of enhanced energetic neutral atom emission that was not predicted by any theory. The origins of this ribbon, which stretches more than 300 degrees across the sky, remain unknown. McComas et al. review IBEX observations, current understanding of the heliosphere, hypotheses that have been proposed to explain the ribbon, and directions for future research.
Source: Geophysical Research Letters, doi:10.1029/2011GL048763, 2011 http://dx.doi.org/10.1029/2011GL048763
Title: IBEX observations of heliospheric energetic neutral atoms: Current understanding and future directions
Authors: D. J. McComas: Southwest Research Institute, San Antonio, Texas, USA, and Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, Texas, USA; H. O. Funsten: Los Alamos National Laboratory, Los Alamos, New Mexico, USA; S. A. Fuselier: Lockheed Martin Advanced Technology Center, Palo Alto, California, USA; W. S. Lewis: Southwest Research Institute, San Antonio, Texas, USA; E. Mobius: Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, New Hampshire, USA; N. A. Schwadron: Southwest Research Institute, San Antonio, Texas, USA, and Physics Department, University of New Hampshire, Durham, New Hampshire, USA.
NEW DETAIL ON AURORAS
High-resolution imaging from spacecraft is revealing new detail on structures in bright, dynamic auroras. In the auroral regions where particles are accelerated to high energies, dynamic structures evolve on time scales of seconds or less, though the processes that drive particle acceleration and transfer of energy to small scales are not fully understood. Chaston et al. show how new spaceborne auroral imagery combined with simultaneous particle measurements can help improve understanding of the physical processes involved in the aurora. In particular, they show how magnetic reconnection (in which magnetic field lines break and reconnect, releasing energy), tearing, and sheared flows can transfer energy from larger to smaller scales and help form the auroral structures observed.
Source: Geophysical Research Letters, doi:10.1029/2011GL049185, 2011 http://dx.doi.org/10.1029/2011GL049185
Title: Cross-scale coupling in the auroral acceleration region
Authors: C. C. Chaston: Space Sciences Laboratory, University of California, Berkeley, California, USA; K. Seki: Solar Terrestrial Environment Laboratory, University of Nagoya, Nagoya, Japan; T. Sakanoi: Graduate School of Science, Planetary Plasma and Atmospheric Research Center, University of Tohoku, Sendai, Japan; K. Asamura: Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan; M. Hirahara: Department of Earth and Planetary Science, Graduate School of Science, University of Tokyo, Tokyo, Japan; C. W. Carlson: Space Sciences Laboratory, University of California, Berkeley, California, USA.
