  Thermo-elasticity couples the deformation of an elastic (solid) body to its
temperature and vice-versa. It is a solid-like property. Highlighting such
property in liquids is a paradigm shift: it requires long-range collective
interactions that are not considered in current liquid descriptions. The
present pioneering microthermal studies provide evidence for such solid-like
correlations. It is shown that ordinary liquids emit a modulated thermal signal
when applying a low frequency (Hz) mechanical shear stress. The liquid splits
in several tenths microns wide thermal bands, all varying synchronously and
separately with the applied stress wave reaching a sizable amplitude of $\pm$
0.2 {\deg}C. This thermal property is unknown in liquids. Thermo-mechanical
coupling challenges a dogma in fluid dynamics: the liquid responds
collectively, adapts its internal energy to external shear strain and is not
governed by short relaxation times responsible of instant thermal dissipation.
The proof of thermomechanical coupling opens the way to a new generation of
energy-efficient temperature converters.
