The present study explains a correlation technique for comparison of different stellar populations in M 33. The radial gradient of the ratio blue to red stars (B/R) obtained by Humphreys & Sandage (1980) and predicted by the evolutionary models of MLA is confirmed. The present study confirms the existence of the radial gradient of the ratio (OB/R) in M 33. Using a new approach in estimating the errors on the ratio (OB/R) and, on the other hand, the correlation between OB star-candidates and RSGs in the central region of M 33. Considering the results, we believe that the observational evidence for a radial gradient of the ratio (OB/R) is real.
© European Southern Observatory (ESO) 1998
Online publication: August 6, 1998