  We study different phenomenological signatures associated with new spin-2
particles. These new degrees of freedom, that we call hidden gravitons, arise
in different high-energy theories such as extra-dimensional models or
extensions of General Relativity. At low energies, hidden gravitons can be
generally described by the Fierz-Pauli Lagrangian. Their phenomenology is
parameterized by two dimensionful constants: their mass and their coupling
strength. In this work, we analyze two different sets of constraints. On the
one hand, we study potential deviations from the inverse-square law on
solar-system and laboratory scales. To extend the constraints to scales where
the laboratory probes are not competitive, we also study consequences on
astrophysical objects. We analyze in detail the processes that may take place
in stellar interiors and lead to emission of hidden gravitons, acting like an
additional source of energy loss.
