On tangential varieties of rational homogeneous varieties

The sphericality of tangential varieties of rational homogeneousvarieties is determined. The homogeneous coordinate rings andrings of covariants of the tangential varieties of homogenouslyembedded compact Hermitian symmetric spaces (CHSS) are determined.Bounds on the degrees of generators of the ideals of tangentialvarieties of CHSS are given, and more explicit information isobtained about the ideals in certain cases.