ИСТИНА

We performed HI and optical long-slit observations of a spiral galaxy UGC11919 to study its kinematics and stellar population. The previous studies gave basis to suspect that this galaxy possesses a peculiarly low mass-to-light ratio M/L of stellar population. The stellar mass-to-light ratio estimated for different evolutionary models using both the broad-band magnitudes and the detailed spectral data confirm this peculiarity if the disk inclination angle i≥30o, as it follows from the optical isophotes and agrees with the HI data cube. However, the HI data cube also admits the lower value of i=13o, where the peculiarity of M/L ratio disappears. The thickness of stellar disk corresponding to the measured velocity dispersion of stellar population also gives evidence of the low inclination. We conclude that the stellar population of this galaxy is not peculiar, however the flatness of optical isophotes is surprisingly large for the nearly face-on disk, evidencing that its stellar disk may be non-axisymmetric. The derived stellar kinematic profiles reveal a signature of kinematically decoupled nuclear disk in the galaxy. Using different evolution models we estimated stellar metallicity and the mean luminosity-weighted stellar age for the bulge, disk and nuclear disk of this galaxy. We show that the disk of UGC11919 is dynamically overheated independently of the adopted inclination angle - probably as the result of the gravitational interaction with companions noticeable in the HI line.