NGC 5533: decoupled nucleus and global structure

An isolated regular Sab galaxy NGC 5533 was observed at the 6m telescope of the Special Astrophysical Observatory RAS (Nizhnij Arkhyz, Russia) with the Multi-Pupil Field Spectrograph and scanning Fabry-Perot interferometer and at the 1m telescope of the Special Astrophysical Observatory through the BVRI filters with a CCD detector. Its unresolved nucleus was found to be chemically and dynamically decoupled. The central mass is estimated as 3.5 · 10 ⁹M_⊙. The global photometric structure reveals a presence of two disk components, the inner one being typical for early-type galaxies and the outer one being more extended and with low surface brightness. An attempt is made to relate an origin of the decoupled nucleus and that of the multi-tier structure of the global disk.