An Astrometric Study of Procyon

We report on the analysis of observations of Procyon obtained with the Multichannel Astrometric Photometer during the years 1986-2004. While the results significantly increase the precision of the estimated characteristics of the components of the system, they are generally in good agreement with the most recent studies. The F5 IV primary is found to have a mass of 1.43 ± 0.034 M⊙, while the white dwarf companion's mass is 0.58 ± 0.014 M⊙. The distance modulus is 2.277 ± 0.005 mag, yielding an absolute visual magnitude for the combined light of the system of 2.640 ± 0.006 and an absolute visual magnitude of the secondary of 13.20 ± 0.05. The residuals of the fit of the positions of the photocenter to the excepted orbit support the parameters of that orbit, showing only a slight deviation in right ascension. The most significant improvements in our knowledge of the binary system can be made with further measurements of the separation of the components. The masses found here tend to reaffirm the recent models of the nature of the primary and secondary stars.