The binarity of Galactic dwarf stars along with effective temperature
  and metallicity
  The fraction of binary stars (fb) is one of most valuable tool to probe the
star formation and evolution of multiple systems in the Galaxy. We focus on the
relationship between fb and stellar metallicity ([Fe/H]) by employing the
differential radial velocity (DRV) method and the large sample observed by the
Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST).
Main-sequence stars from A- to K-types in the third data release (DR3) of
LAMOST are selected to estimate fb. Contributions to a profile of DRV from
radial velocity (RV) error of single stars (\sigma) and orbital motion of
binary stars are evaluated from the profile of DRV. Finally, we employ 365,911
stars with randomly repeating spectral observations to present a detailed
analysis of fb and \sigma in the two-dimensional (2D) space of Teff and [Fe/H].
The A-type stars are more likely to be companions in binary star systems than
other stars. Furthermore, the reverse correlation between fb and [Fe/H] can be
shown statistically, which suggests that fb is a joint function of Teff and
[Fe/H]. At the same time, \sigma of the sample for different Teff and [Fe/H]
are fitted. Metal-rich cold stars in our sample have the best RV measurement.
