Jade Touresse successfully defended her doctoral thesis on the propagation of solar coronal jets in the inner heliosphere
15 Sep. 2026
- Congratulations to Jade Touresse , who successfully defended his thesis entitled "Propagation of solar coronal jets in the inner heliosphere: Investigating a solar origin scenario for switchbacks"
- Abstract
- The Parker Solar Probe (PSP) mission has revealed the ubiquity of switchbacks (SBs): sharp magnetic deflections in the nascent solar wind. Their origin represents a major question for understanding solar wind acceleration and heating. Among the proposed formation mechanisms, solar jets—collimated, impulsive plasma outflows associated with magnetic reconnection—are considered promising candidates because they transport magnetic twist into the heliosphere. Their dynamics are investigated through three-dimensional parametric magnetohydrodynamic simulations, complemented by observational and in situ analyses.
- As part of this PhD thesis, jet propagation has been numerically studied through different background solar atmospheres. Two main components were identified: an untwisting Alfvénic wavefront and a dense plasma outflow, whose spatial decoupling depends on the background atmosphere. Force-balance analysis showed that the dense outflow generates compressive fronts capable of steepening into shocks, whereas the Alfvénic wavefront transported magnetic twist within a coherent vortical structure.
- An observational campaign at the THEMIS solar telescope investigated jet rotation and the magnetic topology of source regions. The direct injection of magnetic U-loops was tested and ruled out as a primary SB formation mechanism because such structures rapidly straighten after formation. By contrast, synthetic in situ measurements showed that jet-driven untwisting Alfvénic wavefronts naturally produced SB-like magnetic deflections.
- The PSP trajectory during its 22nd perihelion was incorporated into the simulations, providing the first 3D characterization of SB magnetic geometry within a jet. A complex internal structure was revealed, and the magnetic deflection angle was found to depend on the local plasma beta. Because fully reversed SBs were not produced, a two-step scenario was favoured: seed perturbations generated by jets, subsequently amplified by solar-wind processes, particularly expansion. This thesis thus establishes a direct physical link between solar jets and SBs.
- Date and Venue of the Defense
- Friday, September 11th, 2026 at 2:00 p.m.
- Amphithéâtre Durand, Bâtiment Esclangon, campus Jussieu, Sorbonne Université
- Examination Committee
- Eric BUCHLIN: CNRS Senior Research Scientist, IAS (France) - Reviewer
- Mark LINTON: Astrophysicist and WISPR Principal Investigator, NRL (USA) - Reviewer
- Andrea CIARDI: Professor, LUX (France) - Chair
- Karine BOCCHIALINI: Professor, IAS (France) - Examiner
- Marco VELLI: Professor, UCLA (USA) - Examiner
- Etienne PARIAT: CNRS Research Scientist, FSLAC, LPP (France) - Supervisor
- Clara FROMENT: CNRS Research Scientist, LPC2E (France) - Co-supervisor
