Why the Sun's atmosphere is hotter than its surface
CNRS
A layer beneath the Sun’s surface, acting as a pan of boiling water, is thought to generate a small-scale magnetic field as an energy reserve which, once it emerges from the star, heats the successive layers of the solar atmosphere via networks of mangrove-like magnetic roots and branches[1]. So what source of energy can heat the atmosphere and maintain it at such high temperatures? The scientists also discovered that a structure resembling a mangrove forest appears around the solar mesospots: tangled ‘chromospheric roots’ dive into the spaces between the granules, surrounding ‘magnetic tree trunks’ that rise up towards the corona and are associated with the larger-scale magnetic field. Thin plasma jets near the tree trunks are also produced and are associated with recently discovered spicules[3]. The researchers found that the energy fluxes of their mechanisms match those required by all studies to maintain the temperature of the plasma in the solar atmosphere, namely 4,500 W/m2 in the chromosphere and 300 W/m2 in the corona.