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This Letter reports the first observational estimate of the heating rate in the slowly expanding solar corona. The analysis exploits the simultaneous remote and local observations of the same coronal plasma volume with the Solar Orbiter/Metis and the Parker Solar Probe instruments, respectively, and relies on the basic solar wind magnetohydrodynamic equations. As expected, energy losses are a minor fraction of the solar wind energy flux, since most of the energy dissipation that feeds the heating and acceleration of the coronal flow occurs much closer to the Sun than the heights probed in the present study, which range from 6.3 to 13.3 solar radii. The energy deposited to the supersonic wind is then used to explain the observed slight residual wind acceleration and to maintain the plasma in a non-adiabatic state. As derived in the Wentzel-Kramers-Brillouin limit, the present energy transfer rate estimates provide a lower limit, which can be very useful in refining the turbulence-based modeling of coronal heating and subsequent solar wind acceleration.

Additional file 1: Supplementary File S1. Tag sequences for flanking and peak markers identified within the QTL regions. Two variant alleles for each SNP were denoted as ‘query’ and ‘hit’.

Additional file 2: Supplementary File S2. Fasta sequence of M. truncatula cold tolerance related gene dehydration-responsive element-binding protein 1C (also known as CBF5) obtained from the National Center for Biotechnology Information (NCBI).