|
Description
We have used interferometric and spectroscopic observations of HR 8257 to determine a three-dimensional orbit of the system. The orbit has a period of 12.21345 days and an eccentricity of 0.2895. The masses of the F0 and F2 dwarf components are 1.56 and 1.38M_{sun}_, respectively, with fractional errors of 1.4%. Our orbital parallax of 13.632+/-0.095mas, corresponding to a distance of 73.4+/-0.6pc, differs from the Hipparcos result by just 2% and has a significantly smaller uncertainty. From our spectroscopic observations and spectral energy distribution modeling we determine the component effective temperatures and luminosities to be T_eff_(A)=7030+/-200K and T_eff_(B)=6560+/-200K and L_A_=9.4+/-0.3L_{sun}_ and L_B_=4.7+/-0.2L_{sun}_. The primary rotates pseudosynchronously, while the secondary is not far from its pseudosynchronous rotational velocity. Although both early-F stars are slowly rotating, neither component of this close binary is an Am star. A comparison with evolutionary tracks indicates that the stars are slightly metal poor, and although the components have evolved away from the zero-age main sequence, they are both still dwarfs.
|
