  We present high precision radial velocities (RVs) of double-lined
spectroscopic binary stars HD78418, HD123999, HD160922, HD200077 and HD210027.
They were obtained based on the high resolution echelle spectra collected with
the Keck I/Hires, Shane/CAT/Hamspec and TNG/Sarge telescopes/spectrographs over
the years 2003-2008 as a part of TATOOINE search for circumbinary planets. The
RVs were computed using our novel iodine cell technique for double-line binary
stars. The precision of the RVs is of the order of 1-10 m/s. Our RVs combined
with the archival visibility measurements from the Palomar Testbed
Interferometer allow us to derive very precise spectroscopic/astrometric
orbital and physical parameters of the binaries. In particular, we derive the
masses, the absolute K and H band magnitudes and the parallaxes. The masses
together with the absolute magnitudes in the K and H bands enable us to
estimate the ages of the binaries.
  These RVs allow us to obtain some of the most accurate mass determinations of
binary stars. The fractional accuracy in m*sin(i) only and hence based on the
RVs alone ranges from 0.02% to 0.42%. When combined with the PTI astrometry,
the fractional accuracy in the masses ranges in the three best cases from 0.06%
to 0.5%. Among them, the masses of HD210027 components rival in precision the
mass determination of the components of the relativistic double pulsar system
PSRJ0737-3039. In the near future, for double-lined eclipsing binary stars we
expect to derive masses with a fractional accuracy of the order of up to
~0.001% with our technique. This level of precision is an order of magnitude
higher than of the most accurate mass determination for a body outside the
Solar System - the double neutron star system PSRB1913+16.
