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Séminaire du Jeudi 7 juin 2018

Coronal mass ejections, from the Sun to the interplanetary medium

Miho Janvier (IAS)
Thursday June 7th - 11am
IPAG Seminar Room - IPAG

Coronal Mass Ejections (CMEs) are large disturbances emanating from the Sun and are associated with flaring activity at our star, also called solar flares. They transport solar plasma and magnetic field in the interplanetary medium and can impact the space environment of the planets and small bodies of the solar system. Remote-sensing instruments on board spacecraft can monitor the evolution of the regions they originate from, their structures, as well as their evolution and their ejection in the Sun’s atmosphere.

Away from the Sun, it is difficult to track these expanding structures because of their low density. Multiple interplanetary probes, located at different distances from the Sun, allow us to directly probe the plasma and magnetic field properties of these interplanetary CMEs (ICMEs). In particular, we find that ICMEs are generically made of substructures such as a turbulent sheath preceding a magnetic ejecta. This ejecta sometimes showcase a coherent structure, similar to the one seen prior to the eruption at the Sun.

With in situ data, it is also possible to report the evolution of some events during their propagation in the solar system. Recently, we have proposed new statistical methods that allow us to understand the generic features of the sheath shock and magnetic coherent structure shape in 3D, as well as the transport of magnetic flux and helicity away from the Sun. These studies also provide a better comprehension on the solar wind interaction processes taking place during the evolution of ICMEs.

The launch of dedicated heliospheric missions such as Solar Orbiter (ESA) will allow to probe the region close to the Sun and give away precious information on how CMEs behave just after their injection in the interplanetary medium.


Sous la tutelle de:

tutelles

Sous la tutelle de:

CNRS Université Grenoble Alpes