Magnetic nulls and super-radial expansion in the solar corona

Magnetic fields in the sun's outer atmosphere -- the corona -- control both solar-wind acceleration and the dynamics of solar eruptions. We present the first clear observational evidence of coronal magnetic nulls in off-limb linearly polarized observations of pseudostreamers, taken by the Coronal Multichannel Polarimeter (CoMP) telescope. These nulls represent regions where magnetic reconnection is likely to act as a catalyst for solar activity. CoMP linear-polarization observations also provide an independent, coronal proxy for magnetic expansion into the solar wind, a quantity often used to parameterize and predict the solar wind speed at Earth. We introduce a new method for explicitly calculating expansion factors from CoMP coronal linear-polarization observations, which does not require photospheric extrapolations. We conclude that linearly-polarized light is a powerful new diagnostic of critical coronal magnetic topologies and the expanding magnetic flux tubes that channel the solar wind

Existence of two MHD reconnection modes in a solar 3D magnetic null point topology

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Existence of two MHD reconnection modes in a solar 3D magnetic null point topology

International audienc

Existence of two MHD reconnection modes in a solar 3D magnetic null point topology

International audienc

Coronal jets in an inclined coronal magnetic field : a parametric 3D MHD study

International audienceX-ray solar coronal jets are short-duration, fast, well collimated plasma brightenings occurring in the solar corona. To explain and understand the processes driving the jets, one must be able to model an explosive release of free energy. Magnetic reconnection is believed to play a key role in the generation of these energetic bursting events. The model of jets that we have been developing is based on a magnetic field constructed by embedding a vertical magnetic dipole in a uniform open magnetic field. In this study, we investigate the influence of the inclination of the open field on the properties of the jet using numerical simulations. We will show that the inclination of the open field is of critical importance for the properties of the jet such as the energy released. We conclude that the characteristics of the open field at the time of observations are a central criterion that must be taken into account and reported on in observational studies

Dynamics of a prominence observed in Mg II lines by IRIS

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Dynamics of a prominence observed in Mg II lines by IRIS

International audienc

Dynamics of a prominence observed in Mg II lines by IRIS

International audienc