Characterization of the Companion to $\mu$ Her
  $\mu$ Her is a nearby quadruple system with a G-subgiant primary and several
low mass companions arranged in a 2+2 architecture. While the BC components
have been well characterized, the Ab component has been detected
astrometrically and with direct imaging but there has been some confusion over
its nature, in particular whether the companion is stellar or substellar. Using
near-infrared spectroscopy we are able to estimate the spectral type of the
companion as a M4$\pm$1V star. In addition, we have measured the astrometry of
the system for over a decade. We combined the astrometry with archival radial
velocity measurements to compute an orbit of the system. From the combined
orbit, we are able to compute the mass sum of the system. Using the estimated
mass of the primary, we estimate the mass of the secondary as 0.32 M_sun, which
agrees with the estimated spectral type. Our computed orbit is preliminary due
to the incomplete orbital phase coverage, but it should be sufficient to
predict ephemerides over the next decade.
