Search Publications
Kelvin Helmholtz Instability in Planetary Magnetospheres
Wing, Simon; Delamere, Peter A.; Johnson, Jay R.
Kelvin-Helmholtz instability plays a particularly important role in plasma transport at magnetospheric boundaries because it can control the development of a turbulent boundary layer, which governs the transport of mass, momentum, and energy across the boundary. Waves generated at the interface can also couple into body modes in the plasma sheet a…
Review of Solar Wind Entry into and Transport Within the Plasma Sheet
Escoubet, C. P.; Wing, S.; Lavraud, B. +8 more
The plasma sheet is populated in part by the solar wind plasma. Four solar entry mechanisms are examined: (1) double cusp or double lobe reconnection, (2) Kelvin-Helmholtz Instability (KHI), (3) Kinetic Alfvén waves (KAW), and (4) Impulsive Penetration. These mechanisms can efficiently fill the plasma sheet with cold dense ions during northward in…
Solar Cycle Variation in Solar Irradiance
Solanki, S. K.; Yeo, K. L.; Krivova, N. A.
The correlation between solar irradiance and the 11-year solar activity cycle is evident in the body of measurements made from space, which extend over the past four decades. Models relating variation in solar irradiance to photospheric magnetism have made significant progress in explaining most of the apparent trends in these observations. There …
The Extended Cycle of Solar Activity and the Sun's 22-Year Magnetic Cycle
Cliver, E. W.
The Sun has two characteristic migrations of surface features—the equatorward movement of sunspots and the poleward movement of high-latitude prominences. The first of these migrations is a defining aspect of the 11-yr Schwabe cycle and the second is a tracer of the process that culminates in solar polarity reversal, signaling the onset of the 22-…
Solar Polar Fields and the 22-Year Activity Cycle: Observations and Models
Petrie, G. J. D.; Petrovay, K.; Schatten, K.
We explore observations and models of the interacting, cyclical behavior of the active regions and the polar magnetic fields of the Sun. We focus on observational evidence of these fields interacting across the corridor between active and polar latitudes. We present observations of diverse magnetic signatures on, above and beneath the solar surfac…
The Sun's Interior Structure and Dynamics, and the Solar Cycle
Thompson, M. J.; Howe, R.; Broomhall, A. -M. +2 more
The Sun's internal structure and dynamics can be studied with helioseismology, which uses the Sun's natural acoustic oscillations to build up a profile of the solar interior. We discuss how solar acoustic oscillations are affected by the Sun's magnetic field. Careful observations of these effects can be inverted to determine the variations in the …
X-Ray Observations of Powerful AGN Outflows. Implications for Feedback
Pounds, Ken
Highly ionised winds with velocities ∼0.1-0.2 c were first detected in X-ray spectra of non-BAL AGN a decade ago. Subsequent observations and archival searches have shown such winds to be a common feature of luminous AGN, increasing the belief that powerful ionised winds have a wider importance in galaxy feedback models. Paradoxically, for the bes…
Solar Wind Turbulence and the Role of Ion Instabilities
Bale, S. D.; Alexandrova, O.; Horbury, T. S. +2 more
Solar wind is probably the best laboratory to study turbulence in astrophysical plasmas. In addition to the presence of magnetic field, the differences with neutral fluid isotropic turbulence are: (i) weakness of collisional dissipation and (ii) presence of several characteristic space and time scales. In this paper we discuss observational proper…
In-Situ Observations of Reconnection in Space
Phan, Tai; Paschmann, Götz; Øieroset, Marit
This paper gives an overview of the insights into the magnetic reconnection process obtained by in-situ measurements across current sheets found in planetary magnetospheres and the solar wind. Emphasis is placed on results that might be of interest to the study of reconnection in regions where no in-situ observations are available. These results i…
The Dynamic Quasiperpendicular Shock: Cluster Discoveries
Bale, S. D.; Krasnoselskikh, V.; Walker, S. N. +9 more
The physics of collisionless shocks is a very broad topic which has been studied for more than five decades. However, there are a number of important issues which remain unresolved. The energy repartition amongst particle populations in quasiperpendicular shocks is a multi-scale process related to the spatial and temporal structure of the electrom…