The Orbit of the Nearby Low - Mass Binary Gliese 600

We have computed a combined spectroscopic–interferometric orbit for the nearby binary Gliese 600 discovered by us. The orbital period is 2.78 years, and the semimajor axis is 100 mas (0.1′′). Its M0 V components are almost identical and have a mass of 0.5M(. The mass ratio is uncertain because of the low radialvelocity semiamplitude (7 km s–1) associated with the low orbital inclination (37°). The orbital parallax of the binary (52 ± 11 mas) matches its dynamical and photometric parallaxes but differs significantly from the Hipparcos parallax (44.3 ± 1.6) mas; the latter was probably distorted by the orbital motion that was not taken into account. © 2000 MAIK “Nauka/Interperiodica”.