It’is all there on the Sun, even tornadoes, in the form of huge swirls of gas at very high temperatures that extend for several thousand kilometers into our star’s atmosphere and last on average a few tens of minutes. A team of researchers led by Mariarita Murabito (INAF, the Italian National Institute for Astrophysics) that includes scientists of the Italian Space Agency (ASI) and the Warwick University has provided the first observational proof that solar tornadoes are produced by swirling magnetic fields. The latter, which permeate the atmosphere of the Sun, are the main engine of the dynamical processes of the solar plasma. The scientific discovery, which will be published in an article of the Astronomy & Astrophysics journal, was achieved thanks to outstanding measurements taken with the INAF IBIS instrument (Interferometric Bidimensional Spectrometer) at the DST solar telescope in New Mexico (USA). The IBIS unique observations allowed to make the three dimensional tomography of the magnetic fields spiralling in the tornado and measure their faint polarimetric signals.

“Since their discovery in 2011, the numerical simulations have suggested that the rotating structures observed in the solar chromosphere are tracers of magnetic structures that by their rotation force the solar plasma to move upwards along the magnetic field lines through centrifugal force” says Mariarita Murabito, researcher at INAF in Rome. “This plasma flow can be accelerated towards the overlying layers of the Sun’s atmosphere. There were however no observational evidences of these processes. Confirming the magnetic nature of solar tornadoes is an important knowledge step”.

The huge solar tornadoes, whose size is comparable with that of the Europe continent, connect the different layers of the Sun’s atmosphere acting as a channel for the energy transport towards its outermost regions.

"The study of the transport and dissipation of energy in the Sun's atmosphere is of fundamental importance for understanding the heating mechanisms of the outer regions of the Sun’s atmosphere and the acceleration of the solar wind" says Marco Stangalini, researcher at ASI. "The magnetic fields swirling in these vortices represent the ideal physical conditions for the excitation of magnetic waves, which are considered to be one of the main players in the heating of the solar corona and in the acceleration of the solar wind. It is the first time that, thanks to IBIS high resolution spectropolarimetric data, the full three-dimensional tomography of the magnetic fields in these structures was possible. In the near future the improved polarimetric sensitivity of upcoming new instrumentation shall allow to perform these observations more easily, providing us with valuable information about these processes in the solar atmosphere.” remarks Stangalini.

“The observations performed with IBIS over the past years have advanced our knowledge of the solar atmosphere, in particular of the structure and dynamics of the chromosphere, of the evolution of magnetic elements at small and large scales, and of the excitation and propagation of waves in magnetic regions” says Ilaria Ermolli, of INAF in Rome and co-author of the study. "A team of researchers and technologists of various INAF institutes and Universities is working to the update of the instrument, in order to operate it soon to get new observations of the Sun’s atmosphere with the resolution required to advance our understanding of physical processes underlying the solar activity and space weather ” Ermolli concludes.

The study is being published in the Astronomy and & Astrophysics Journal paper entitled Unveiling the magnetic nature of chromospheric vortices” by Mariarita Murabito, Juie Shetye, Marco Stangalini, Erwin Verwichte, Tony Arber, Ilaria Ermolli, Fabrizio Giorgi, Tom Goffrey. It can be found in the forthcoming papers at the following link:

https://www.aanda.org/component/article?access=doi&doi=10.1051/0004-6361/202038360