On the chemical evolution of our galaxy

We have investigated the chemical evolution of the solar neighborhood with a particular emphasis on the helium abundance and the current supernova (SN) rate, while taking into account the effects of the stellar mass loss on nucleosynthesis in stars. We found that the Scale IMF can reproduce the solar-helium abundance as well as the current ratio of type-Ia to type-(Ib+II) SNe for a suitable choice of the close-binary fraction. A current type-Ia to type-(Ib+II) SNe ratio as low as 0.1 is favored in order to reproduce the solar-iron abundance. We have noticed that there exists a method to estimate the mass-to-luminosity ratio of our Galaxy and the Hubble constant by assuming that the current SNe rate of our Galaxy is the same as that of external Sbc galaxies. By combining our best model prediction, M/L(B) = 12.3 h(2), with the observed value, M/L(B) = 7.6 h, we obtained M/L(B) = 4.7 and H-0 similar to 62 [km s(-1)Mpc(-1)] with a fairly large uncertainty.