A Precise Orbit Determination of χ¹ Orionis from Astrometric and Radial Velocity Data

Abstract

We have derived an accurate orbit of χ¹ Orionis (HD 39587, HIP 27913, HR 2047) by combining precise astrometric and radial velocity data. The combined orbital analysis yields P=5156.7+/-2.5 days, K₁=1.885+/-0.004 km s^-1, α₁=94.8+/-1.6 mas, e=0.451+/-0.003, and mass ratio (M₂/M₁) q=0.15+/-0.005. The mass ratio derived here is among the smallest well-determined ratio for a G-type dwarf primary star. We have also obtained a parallax of χ¹ Orionis, 115.93+/-1.02 mas, in excellent agreement with the Hipparcos value.