132 results found
<jats:p>&lt;p&gt;The plasma instruments, Mutual Impedance Probe (MIP) and Langmuir Probe (LAP), part of the Rosetta Plasma Consortium (RPC), onboard the Rosetta mission to comet 67P revealed a population of cold electrons (&lt;1eV) (Engelhardt et al., 2018; Wattieaux et al, 2020; Gilet et al., 2020). This population is primarily generated by cooling warm (~10eV) newly-born cometary electrons through collisions with the neutral coma. What is surprising is that the cold electrons were detected throughout the escort phase, even at very low outgassing rates (Q&lt;1e26 s&lt;sup&gt;-1&lt;/sup&gt;) at large heliocentric distances (&gt;3 AU), when the coma was not thought to be dense enough to cool the electron population significantly.&lt;/p&gt;&lt;p&gt;&amp;#160;Using a collisional test particle model, we examine the behaviour of electrons in the coma of a weakly outgassing comet and the formation of a cold population through electron-neutral collisions. The model incorporates three electron sources: the solar wind, photo-electrons produced through ionisation of the cometary neutrals by extreme ultraviolet solar radiation, and secondary electrons produced through electron-impact ionisation.&lt;/p&gt;&lt;p&gt;The model includes different electron-water collision processes, including elastic, excitation, and ionisation collisions.&lt;/p&gt;&lt;p&gt;&amp;#160;The electron trajectories are shaped by electric and magnetic fields, which are taken from a 3D collisionless fully-kinetic Particle-in-Cell (PIC) model of the solar wind and cometary plasma&amp;#160; (Deca 2017, 2019). We use a spherically symmetric coma of pure water, which gives a r&lt;sup&gt;-2&lt;/sup&gt; profile in the neutral density. Throughout their lifetime, electrons undergo stochast
Rymer A, Mandt K, Hurley D, et al., Solar System Ice Giants: Exoplanets in our Backyard
Future remote sensing of exoplanets will be enhanced by a thoroughinvestigation of our solar system Ice Giants (Neptune-size planets). What canthe configuration of the magnetic field tell us (remotely) about the interior,and what implications does that field have for the structure of themagnetosphere; energy input into the atmosphere, and surface geophysics (forexample surface weathering of satellites that might harbour sub-surfaceoceans). How can monitoring of auroral emission help inform future remoteobservations of emission from exoplanets? Our Solar System provides the onlylaboratory in which we can perform in-situ experiments to understand exoplanetformation, dynamos, systems and magnetospheres.
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