Unveiling the heliospheric magnetic field: from the largest spatial scale to its turbulent dissipation

DASSO, S.

Salta

Conferencia; 53 Reunión de la Asociación Argentina de Astronomía; 2010

Asociación Argentina de Astronomía

From the birth of the space age in the 60’s, it is well known that the helio-spheric magnetic field plays a major role on the dynamics of the heliosphere,in particular on the progressive change of mesoscale transient structures, onthe solar wind heating, and on the transport of suprathermal particle in thismedium. The Parker spiral was the zero-order firm base to describe theglobal and stationary magnetic configuration of the heliosphere; however,after proposing this basal model, several departures have been introduced,both, theoretically and/or by observations. Some relevant departures fromthe stationary solar wind are given by huge magnetic flux ropes (typical sizesnear Earth of  0.1 astronomical unit) which are erupted from the Sun. Thepresence of these transients in the interplanetary medium have importantconsequences on several heliospheric objects, as for instance on the inter-change of energy and momentum between the solar wind and planetarymagnetospheres. Magnetic fluctuations in the solar wind are coupled withplasma velocity fluctuations (e.g., forming Elsasser structures) and play animportant role on the energy dissipation, via turbulent cascades from largerto smaller scales, and also on the propagation of solar and galactic cosmicrays through the heliosphere.The study of the heliospheric magnetic field for a wide space/time scalesrange has advanced greatly in the last few years thanks to the new generationof multispacecraft observations and high performance numerical simulations.The present work presents a review on the magnetic field in the heliosphere,focusing on the evolution of mesoscale transient magnetic structures and onthe solar wind turbulent properties.