The Sun’s outermost layer is the corona, a region of low-density gas which constantly emits a flow of charged particles known as the solar wind, and where coronal mass ejections originate. Coronal mass ejections are gigantic clouds of plasma, which shoot from the Sun and into interplanetary space at speeds of up to thousands of kilometres per second.
Coronal mass ejections are basic plasma physics
Coronal mass ejections form as twisted magnetic flux ropes when the Sun’s complex magnetic field changes. Although coronal mass ejections have been studied for decades, their exact cause, structure and development continue to be largely unknown.
“Most strong disturbances in planetary space environments are caused by coronal mass ejections, and at Earth they can impact the performance of technical systems and hinder their reliability in space and on ground,” explains Emilia Kilpua from the University of Helsinki’s Department of Physics.
Examining the magnetic structure of ejections
“One of our biggest challenges is that, with the current methods, we cannot measure or model the magnetic field of the Sun’s corona with sufficient precision,” says Kilpua.
Her research combines numeric models of the Sun’s corona with observations in a completely new way. The aim is to determine realistically the magnetic structure of coronal mass ejections for the first time.
Sheath regions are like nature’s laboratory
“We are also modelling and analysing the turbulent sheath region,” Kilpua tells.
Sheath regions form ahead of the ejection as it ploughs through the interplanetary space. Sheaths themselves can drive powerful space weather storms, they couple to the evolution of the flux rope and they have a particularly rich internal structure. Such regions are a unique opportunity to study the core processes of plasma physics outside of a laboratory.
“However, sheath are very little studied so far,” she says.
Once the magnetic field of the coronal mass ejections has been resolved and the sheath regions carefully analysed, it will be possible to predict when a magnetic storm will hit near-Earth space.
Information on the structure of the magnetic fields is also needed in order to study which mechanisms and plasma instabilities cause coronal mass ejections and how they interact with each other when they move through interplanetary space.
The competitive ERC Consolidator Grant
The recipients of the European Research Council’s (ERC) Consolidator Grants were announced in December 2016. A total of 2,274 research projects applied for the competitive five-year funding, and 304 were successful. The total amount of funding is €605 million. The ERC Consolidator Grant is intended for successful researchers with 7–12 years of postdoctoral experience.
University of Helsinki researchers who were successful in this funding round were Mikko Niemi, Anna-Liisa Laine and Jaan-Olle Andersoo. In addition, physicists Emilia Kilpua and Aleksi Vuorinen from the Kumpula Science Campus received ERC funding.
ERC Consolidator Grant recipients in the physical sciences: https://erc.europa.eu/sites/default/files/document/file/erc_2016_cog_results_pe.pdf
Further information: Associate Professor Emilia Kilpua, University of Helsinki’s Faculty of Science, +358 50 415 5358, @EmiliaKilpua, emilia.kilpua@helsinki.fi
Minna Meriläinen-Tenhu, sci comms, @MinnaMeriTenhu, +358 50415 0316, minna.merilainen@helsinki.fi