ИСТИНА

Spheroidal stellar systems on various scales include elliptical galaxies, galactic bulges/stellar haloes, and globular stellar clusters. Elliptical galaxies are thought to be formed by major merging of disk galaxies: it is the easiest way to create stellar systems without rotation, whose shape is supported only by anisotropic chaotic motions (by stellar velocity dispersion). However some recent observational findings have put into doubt this commonly accepted scenario. Some features of elliptical galaxies structure can be only explained if minor merging has mostly shaped these spheroidal stellar systems. The bulges of disk galaxies are now divided into two main types: classical bulges resembling elliptical galaxies located INSIDE the large-scale stellar disks and pseudobulges characterized by fast rotation and by the presence of multiple substructures. The ways to form classical bulges and pseudobulges are thought to be different: minor merging for the formers and secular disk evolution for the latters. Many people think that our Galaxy possesses a pseudobulge; but also many people look for signatures of multiple mergers in the outer stellar halo. Globular clusters differ from the (dwarf) spheroidal galaxies by an absence of their own dark matter component. So they cannot be either downscaled version of galaxies or the direct precursors of galaxies during the hierarchical gravitaional clustering of baryons. However they are the oldest stellar systems in the Universe -- it is an observational fact. Their formation mechanisms represent a puzzle yet.