Astrophysical constraints on large extra dimensions

In the Kaluza-Klein (KK) scenario with n large extra dimensions where gravi ty propagates in the 4 + n dimensional bulk of spacetime while gauge and ma tter fields are confined to a four dimensional subspace, the light gravitat ion KK modes can be produced in the Sun, red giants and supernovae. We stud y the energy-loss rates through photon-photon annihilation, electron-positr on annihilation, gravi-Compton-Primakoff scattering, gravi-bremsstrahlung a nd nucleon-nucleon bremsstrahlung, and derive lower limits to the string sc ale M-s. The most stringent lower limit obtained from SN1987A leads to M-s > 30-130 TeV (2.1-9.3 TeV) for the case of two (three) large extra dimensio ns. (C) 1999 Published by Elsevier Science B.V. All rights reserved.