  A central problem of space plasma physics is how protons and electrons are
heated in a turbulent, magnetized plasma. The differential heating of charged
species due to dissipation of turbulent fluctuations plays a key role in solar
wind evolution. Measurements from previous heliophysics missions have provided
estimates of proton and electron heating rates beyond 0.27 au. Using Parker
Solar Probe (PSP) data accumulated during the first ten encounters, we extend
the evaluation of the individual rates of heat deposition for protons and
electrons in to a distance of 0.063 au (13.5 solar radii), in the newly formed
solar wind. The PSP data in the near-Sun environment show different behavior of
the electron heat conduction flux from what was predicted from previous fits to
Helios and Ulysses data. Consequently, the empirically derived proton and
electron heating rates exhibit significantly different behavior than previous
reports, with the proton heating becoming increasingly dominant over electron
heating at decreasing heliocentric distances. We find that the protons receive
about 80% of the total plasma heating at ~ 13 solar radii, slightly higher than
the near-Earth values. This empirically derived heating partition between
protons and electrons will help to constrain theoretical models of solar wind
heating.
