The stellar content of the ring in NGC 660
  We present the results of stellar photometry of the polar-ring galaxy NGC 660 using the Hubble Space Telescope's archival data obtained with the Wide Field Planetary Camera 2. The final list of the resolved stars contains 550 objects, a considerable part of which are blue and red supergiants belonging to the polar ring. The analysis of the Colour Magnitude Diagram for polar ring stars shows that it is best represented by the isochrones with metallicity Z = 0.008. The process of star formation in the polar ring was continuous and the age of the youngest detected stars is about 7 Myr. 
G.M.Karataeva (1), N.A.Tikhonov (2), O.A.Galazutdinova (2), V.A.   Hagen-Thorn (1), V.A.Yakovleva (1)((1) Astronomical Insti...