The bulge-disk orthogonal decoupling in galaxies: NGC 4698

The R-band isophotal map of the Sa galaxy NGC 4698 shows that the inner reg ion of the bulge structure is elongated perpendicularly to the major axis o f the disk; this is also true for the outer parts of the bulge if a paramet ric photometric decomposition is adopted. At the same time, the stellar com ponent is characterized by an inner velocity gradient and a central zero-ve locity plateau along the minor and major axes of the disk, respectively. Th is remarkable geometric and kinematic decoupling suggests that a second eve nt occurred in the formation history of this galaxy.