Fundamental Properties of Co-Moving Stars observed by $Gaia$
  We have estimated fundamental parameters for a sample of co-moving stars
observed by $Gaia$ and identified by Oh et al. (2017). We matched the $Gaia$
observations to the 2MASS and WISE catalogs and fit MIST isochrones to the
data, deriving estimates of the mass, radius, [Fe/H], age, distance and
extinction to 9,754 stars in the original sample of 10,606 stars. We verify
these estimates by comparing our new results to previous analyses of nearby
stars, examining fiducial cluster properties, and estimating the power-law
slope of the local present-day mass function. A comparison to previous studies
suggests that our mass estimates are robust, while metallicity and age
estimates are increasingly uncertain. We use our calculated masses to examine
the properties of binaries in the sample, and show that separation of the pairs
dominates the observed binding energies and expected lifetimes.
