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Laboratory Studies Towards Understanding Comets

Hartogh, Paul; Marboeuf, Ulysse; Mousis, Olivier +13 more

This review presents some of the recent advancements in our understanding of comets facilitated by laboratory studies, need for new laboratory simulations, and predictions for future explorations. With the spacecraft Rosetta at the comet 67P/Churyumov-Gerasimenko, a large volume of science data is expected to follow early results that have been pu…

Solar Dynamics, Rotation, Convection and Overshoot

Thompson, M. J.; Schou, J.; Roth, M. +3 more

We discuss recent observational, theoretical and modeling progress made in understanding the Sun's internal dynamics, including its rotation, meridional flow, convection and overshoot. Over the past few decades, substantial theoretical and observational effort has gone into appreciating these aspects of solar dynamics. A review of these observatio…

Electric Current Circuits in Astrophysics

Frey, Harald U.; Fletcher, Lyndsay; Kuijpers, Jan

Cosmic magnetic structures have in common that they are anchored in a dynamo, that an external driver converts kinetic energy into internal magnetic energy, that this magnetic energy is transported as Poynting flux across the magnetically dominated structure, and that the magnetic energy is released in the form of particle acceleration, heating, b…

Sources of Local Time Asymmetries in Magnetodiscs

Jackman, C. M.; Khurana, K. K.; Kane, M. +2 more

The rapidly rotating magnetospheres at Jupiter and Saturn contain a near-equatorial thin current sheet over most local times known as the magnetodisc, resembling a wrapped-up magnetotail. The Pioneer, Voyager, Ulysses, Galileo, Cassini and New Horizons spacecraft at Jupiter and Saturn have provided extensive datasets from which to observationally …

The Subsurface Structure and Density of Cometary Nuclei

Lamy, P. L.; Toth, I.; Herique, A.

Little is known about the internal structure and density of cometary nuclei. Indirect evidences available so far are not compelling and these questions essentially remain a matter of speculation. It is therefore important to fully exploit the potential sources of information and this is particularly the case of radar observations which have the ca…

The Importance of Long-Term Synoptic Observations and Data Sets for Solar Physics and Helioseismology

Gosain, Sanjay; Broomhall, Anne-Marie; Elsworth, Yvonne +3 more

A casual single glance at the Sun would not lead an observer to conclude that it varies. The discovery of the 11-year sunspot cycle was only made possible through systematic daily observations of the Sun over 150 years and even today historic sunspot drawings are used to study the behavior of past solar cycles. The origin of solar activity is stil…

Multi-scale Structure Formation and Dynamics in Cosmic Plasmas

Balogh, A.; Eastwood, J.; Kaastra, J. +1 more

Measuring Black Hole Spin Using X-Ray Reflection Spectroscopy

Reynolds, Christopher S.

I review the current status of X-ray reflection (a.k.a. broad iron line) based black hole spin measurements. This is a powerful technique that allows us to measure robust black hole spins across the mass range, from the stellar-mass black holes in X-ray binaries to the supermassive black holes in active galactic nuclei. After describing the basic …

Circulation of Heavy Ions and Their Dynamical Effects in the Magnetosphere: Recent Observations and Models

Dandouras, Iannis; Malova, Helmi V.; Grigorenko, Elena E. +13 more

Knowledge of the ion composition in the near-Earth's magnetosphere and plasma sheet is essential for the understanding of magnetospheric processes and instabilities. The presence of heavy ions of ionospheric origin in the magnetosphere, in particular oxygen (O⁺), influences the plasma sheet bulk properties, current sheet (CS) thickness …

Magnetic Helicity, Tilt, and Twist

Pevtsov, Alexei A.; van Driel-Gesztelyi, Lidia; Norton, Aimee A. +2 more

Since its introduction to astro- and solar physics, the concept of helicity has proven to be useful in providing critical insights into physics of various processes from astrophysical dynamos, to magnetic reconnection and eruptive phenomena. Signature of helicity was also detected in many solar features, including orientation of solar active regio…