We analyze the magnetosphere-ionosphere field-aligned currents associated with substorms using the Active Magnetosphere and Planetary Electrodynamics Response Experiment. We report a new phenomenon related to substorm onset: the development of a second pair of R2 field-aligned currents located equatorward of the preexisting R1/R2 currents, especially in the dusk sector. The appearance of such events favors the summer hemisphere, suggesting that ionospheric conductance modulates this phenomenon. During ongoing geomagnetic activity, the events have a quasiperiodicity of approximately 1 hr. We suggest that this phenomenon is related to subauroral polarization streams, which are strong westward flows in the dusk sector midlatitude ionosphere. This paper proposes a new mechanism that describes the formation of these current bifurcations: Consecutive particle injections into the inner magnetosphere during disturbed geomagnetic conditions cause separate partial ring currents to form, leading to the presence of distinct R2 current systems, all flowing into the R1 current.
[1] X-rays can be generated by charge exchange between highly-charged heavy solar wind ions and neutrals. Previously, simulations have only been performed for X-ray emission due to solar wind charge exchange (SWCX) with geocoronal and interstellar neutrals. However, X-rays can also be generated by SWCX with the Moon's tenuous exosphere, which should be detectable by an imaging X-ray instrument located on the Moon. In addition, lunar-based observations of X-ray emission originating from Earth's magnetosheath will be able to provide information on the dynamic response of the bow shock and magnetopause to solar wind variations. Furthermore, X-ray emissions from SWCX within the heliosphere constitute part of the soft X-ray background (SXRB) emission, competing with emissions originating from outside the solar system. Lunar observations of soft X-rays will give additional information about these charge exchange processes and be critical in removing the heliospheric component of the SXRB.
Since the initial discovery of cometary charge exchange emission, more than 20 comets have been observed with a variety of X-ray and UV observatories. This observational sample offers a broad variety of comets, solar wind environments and observational conditions. It clearly demonstrates that solar wind charge exchange emission provides a wealth of diagnostics, which are visible as spatial, temporal, and spectral emission features. We review the possibilities and limitations of each of those in this contribution.
X-ray observations of solar wind charge exchange (SWCX) emission, a nuisance to astrophysicists, will dramatically enhance our ability to determine the structure and variability of the Earth's magnetosheath. Such observations could be made from the lunar surface or an Earth-orbiting spacecraft and will resolve key controversies about magnetopause physics as well as better characterize SWCX emission with the aim of avoiding or removing it from astrophysical observations.
This contribution summarizes the splinter session "Non-thermal processes in coronae and beyond" held at the Cool Stars 17 workshop in Barcelona in 2012. It covers new developments in high energy non-thermal effects in the Earth's exosphere, solar and stellar flares, the diffuse emission in star forming regions and reviews the state and the challenges of the underlying atomic databases. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.