Fleeting Small-scale Surface Magnetic Fields Build the Quiet-Sun Corona

Abstract

Arch-like loop structures filled with million Kelvin hot plasma form the building blocks of the quiet-Sun corona. Both high-resolution observations and magnetoconvection simulations show the ubiquitous presence of magnetic fields on the solar surface on small spatial scales of ∼100 km. However, the question of how exactly these quiet-Sun coronal loops originate from the photosphere and how the magnetic energy from the surface is channeled to heat the overlying atmosphere is a long-standing puzzle. Here we report high-resolution photospheric magnetic field and coronal data acquired during the second science perihelion of Solar Orbiter that reveal a highly dynamic magnetic landscape underlying the observed quiet-Sun corona. We found that coronal loops often connect to surface regions that harbor fleeting weaker, mixed-polarity magnetic field patches structured on small spatial scales, and that coronal disturbances could emerge from these areas. We suggest that weaker magnetic fields with fluxes as low as 10 ^15 Mx and/or those that evolve on timescales less than 5 minutes are crucial to understanding the coronal structuring and dynamics.

Keywords

• Solar extreme ultraviolet emission
• Solar photosphere
• Solar coronal heating
• Solar magnetic fields
• Solar magnetic reconnection
• Magnetohydrodynamics