NEW TEST OF NONSYMMETRIC THEORIES OF GRAVITY - OBSERVATIONAL LIMITS ON GRAVITY-INDUCED DEPOLARIZATION OF SOLAR SPECTRAL-LINES

We show that theories which couple the antisymmetric part of a nonsymmetric-tensor gravitational field to the electromagnetic field predict a depolarization of the Zeeman components of spectral lines emitted by extended, magnetically active regions near the limb of the Sun. This new effect is a consequence of the violation of the Einstein equivalence principle by these nonsymmetric alternatives to general relativity. We show that existing solar-physics data limit the extent of such depolarization and imply that the Sun's antisymmetric charge l.2 must be less than (535 km)2 in Moffat's theory, the prototypical nonsymmetric theory of gravity.