Masses and K-line absolute magnitudes of γ Leonis and 35 Comae

The visual binary system γ Leonis consists of two K giants whose total mass was found by Wilson to be less than 0.6M/sub sun/ when a distance was obtained from K-line absolute magnitudes of both components. Since the orbital period of the system is of order 600 years, the orbital solution has usually been regarded as the most likely explanation of the anomalous mass. We have investigated the uniqueness of the orbital solution. We find that the individual orbital elements are only poorly determined, but that a3/P2 is known to within +- 10%. The anomalous mass of this binary system implies either extensive mass-loss or the need for revisions in the K-line absolute magnitudes. We also investigate the binary system 35 Comae. Wilson has noted that in this system the K-line absolute magnitude of the G8 III primary component implies a total mass of 8 M/sub sun/. However the A component of 35 Comae is not sufficiently luminous to justify such a large total mass. The system has a period of order 700 years, and the uniqueness of the orbital solution is therefore suspect. However, in this case also we have investigated the uniqueness of the orbital solution and find that individual orbital elements are poorly determined, but that a3/P2 is known to within +- 17%. We point out that 35 Comae is known to be very metal rich, in contrast to γ Leonis which is metal poor. We conclude that a composition-dependent correction to the K-line absolute magnitudes provides the simplest explanation of these mass anomalies. Such a correction would also give better agreement with the trigonometric parallaxes of these binary systems