  In the Kaluza-Klein (KK) scenario with n large extra dimensions where gravity
propagates in the 4+n dimensional bulk of spacetime while gauge and matter
fields are confined to a four dimensional subspace, the light graviton KK modes
can be produced in the Sun, red giants and supernovae. We study the energy-loss
rates through photon-photon annihilation, electron-positron annihilation,
gravi-Compton-Primakoff scattering, gravi-bremsstrahlung and nucleon-nucleon
bremsstrahlung, and derive lower limits to the string scale M_S. The most
stringent lower limit obtained from SN1987A leads to $M_S> 30 - 130$ TeV
(2.1-9.2 TeV) for the case of two (three) large extra dimensions.
