  Context. 65 UMa belongs to rather small group of stellar systems of higher
multiplicity, whose inner and outer orbits are well-known. Methods:
Photometric, spectroscopic, and interferometric data were analyzed, revealing
the basic physical properties of the system 65 UMa. A disentangling technique
is used to perform the spectra decomposition. This combined approach allows us
to study the long-term period changes in the system, identifying the period
variation due to the motion on the visual orbit, in addition to a short-term
modulation. Results: We find that the system contains one more component, hence
65 UMa is a sextuple hierarchical system. The most inner pair of components
consists of an eclipsing binary orbiting around a barycenter on a circular
orbit, both components being almost identical of spectral type about A7. This
pair orbits on an eccentric orbit around a barycenter, and the third component
orbits with a period of about 640 days. This motion is reflected in the period
variation in the minima times of the eclipsing pair, as well as in the radial
velocities of the primary, secondary, and tertiary components. Moreover, this
system orbits around a barycenter with the distant component resolved
interferometrically, whose period is of about 118 years. Two more distant
components (4" and 63") are also probably gravitationally bound to the system.
The nodal period of the eclipsing-pair orbit is on the order of only a few
centuries, which makes this system even more interesting for a future
prospective detection of changing the depths of minima. Conclusions: We
identify a unique solution of the system 65 UMa, decomposing the individual
components and even shifting the system to higher multiplicity. The study of
this kind of multiple can help us to understand the origin of stellar systems.
Besides 65 UMa, only another 11 sextuple systems have been studied.
