New Optical Results on gamma-ray Binaries
  We present new optical spectroscopy of the gamma-ray binary LS 5039. Our data
show evidence for sub-orbital modulation in the radial velocities with
amplitude ~7 km/s and period ~Porb/4. This short-term oscillation is stable
over at least 7 years and it is likely triggered by non-radial oscillations of
the O6.5V optical star. We also present the results of a spectroscopic campaign
on MWC 148, the optical counterpart of the new gamma-ray binary candidate HESS
J0632+067. Long-term variations in the Halpha and Hbeta emission line
parameters are clearly detected which, if modulated with the binary orbit,
would imply a period >200 days.
