C. J. Díaz Baso, J. de la Cruz Rodríguez and J. Leenaarts recently published a new article on radiative cooling in the solar chromosphere in A&A. The title of the paper is “An observationally-constrained model of strong magnetic reconnection in the solar chromosphere. Atmospheric stratification and estimates of heating rates”.



Emission in spectral lines that form in the solar chromosphere indicates that the chromosphere is warmer than expected if cooling and heating by radiation are in balance. This indicates that some other processes must supply energy to the chromosphere in order to sustain its temperature. Canonical estimates from the late seventies and early eighties based on time and space-averaged models indicate that this energy input is around 4 kW/m2 for regions with a weak magnetic field, and 20 kW/m2 in regions with a strong magnetic field. We revisited these estimates using multi-line imaging spectropolarimetry with the Swedish 1-m Solar Telescope to derive the energy input on spatial scales of ~100 km and a time resolution of 30 s. We find that it can locally be as much as eight times higher than the old values, and shows spatial structure down to the resolution limit of the telescope. This finding puts new strong constraints on models that aim to explain energy dissipation in the solar atmosphere.


For more information see: Díaz Baso et al. 2021, A&A, in press (arXiv:2012.06229).


The upper panel shows an image of the solar chromosphere taken in the core of the Hα line taken with the Swedish 1-m Solar Telescope. The bright region inside the red box is a location where a strong magnetic field is rising through the chromosphere. The lower panel shows the chromospheric radiative losses based on a 3D model of the solar atmosphere that was constructed based on the observations.
C. J. Díaz Baso.