Solar magnetic fields in chromospheric structures - Approach to the chromospheric heating problem

Our knowledge of the heating mechanisms that are at work in the chromosphere remains highly unconstrained from observational studies. While many heating candidates have been proposed in theoretical studies, the exact contribution from each of them is still unknown. The problem is rather difficult because there is no direct way of estimating the heating terms from chromospheric observations. However, through the study of magnetic fields it is possible to put some constraints on the heating terms. Magnetic fields are, indeed, a key ingredient to explain the topology and flows in the chromosphere: they regulate the dynamics, the energy balance and the atmospheric structures of this layer of the solar atmosphere. We studied the topology of magnetic fields in plage regions, by developing a new version of the well-known weak field approximation (WFA), the spatially-regularised WFA. We, then, focused on the calculation of the radiative losses in a plage region. Our results show that radiative losses in the upper chromosphere form a relatively homogeneous patch that covers the entire plage region. The time analysis shows that in all pixels, the net radiative losses can be split in a periodic component and a static (or very slowly evolving) component. We expand our study to a different type of target, loop structures in active regions. Understand how the magnetic field is connected to loop structures can help to identify the heating mechanisms that are playing a role in these type of active regions. The magnetic field structures is indeed deeply related to the processes that could be heating the chromosphere, like magnetoacoustic waves and Alfven waves dissipation.