Resolving magnetic ORIGINs of the hot solar atmosphere

ERC Starting Grant

The outer atmosphere of the Sun, the corona, is a unique plasma laboratory. It provides key insights into fundamental universal processes such as magnetic reconnection and particle acceleration. Yet, the very existence of the corona in itself is not well understood. It is composed of million Kelvin hot plasma trapped by magnetic fields, and overlies the much cooler 6000 K photosphere, the visible surface of the Sun. All sun-like stars possess such magnetically dominated hotter coronae overlying cooler photospheres. How do magnetic fields regulate mass and energy transport from the cool photosphere to sustain the overlying hot corona? This is a long-standing problem in astrophysics, which lacks a comprehensive explanation, despite proposals of different coronal heating models over the past five decades. The progress is hampered due to the lack of a solid, observationally validated framework of how the corona is magnetically coupled to the photosphere. We propose a holistic strategy to tackle this challenging problem of developing a framework for coronal heating by probing the elusive photosphere-corona connection and comprehensively testing the importance of different magnetic processes in the heating of the outer solar atmosphere. Through this strategy, we will identify key magnetic processes in the cool photosphere that regulate the hot atmosphere. Project ORIGIN will achieve this timely goal by exploiting unique, multi-wavelength observations from the recently launched Solar Orbiter mission, in combination with realistic radiation magnetohydrodynamic (MHD) simulations, and thus gain ground-breaking new insights into the magnetic origins of the hot solar atmosphere.