The spatial structure of the globular cluster M92

We have studied the spatial structure of the globular cluster M92 as a func tion of various intervals of stellar magnitude Delta B and limiting magnitu des B used in star counts. We used astrometric and photometric measurements of a photographic plate obtained with the 2-m reflector of the National As tronomical Observatory of Bulgaria. Differential and integrated apparent (D elta F(r) and F(r)) and spatial (Delta f(r) and f(r)) stellar-density funct ions were considered for the intervals Delta B = (13-15.1(m)), (15.1-16(m)) , (16-17(m)), (17-18(m)), (18-18.5(m)), (18.5-19(m) (19-19.5(m)), (19.5-20( m)), (20-20.5(m)), and (20.5-21(m)) and for the limiting magnitudes B = 15. 1, 16, 17, 18, 18.5, 19, 19.5, 20, 20.5, and 21(m). Analysis of these funct ions indicates that the structure of the cluster varies systematically as w e proceed toward Fainter stars, starting from the transition region between the subgiant branch to the turnoff point of the main sequence in the (V, B -V) diagram. This variation is twofold, First, the radii of spatial zones o f the cluster and the radius of the cluster as a whole homologously increas e according to the same law. Second, in the transition to the outer zones o f the cluster, the rate of increase of the number of faint stars increases with B. We derived empirical relationships describing these variations, tog ether with parameters determining the structure of the cluster.