Is there a compact companion orbiting the late O-type binary star HD
  164816?
  We present a multi-wavelength (X-ray, $\gamma$-ray, optical and radio) study
of HD 194816, a late O-type X-ray detected spectroscopic binary. X-ray spectra
are analyzed and the X-ray photon arrival times are checked for pulsation. In
addition, newly obtained optical spectroscopic monitoring data on HD 164816 are
presented. They are complemented by available radio data from several large
scale surveys as well as the \emph{FERMI} $\gamma$-ray data from its
\emph{Large Area Telescope}. We report the detection of a low energy excess in
the X-ray spectrum that can be described by a simple absorbed blackbody model
with a temperature of $\sim$ 50 eV as well as a 9.78 s pulsation of the X-ray
source. The soft X-ray excess, the X-ray pulsation, and the kinematical age
would all be consistent with a compact object like a neutron star as companion
to HD 164816. The size of the soft X-ray excess emitting area is consistent
with a circular region with a radius of about 7 km, typical for neutron stars,
while the emission measure of the remaining harder emission is typical for late
O-type single or binary stars. If HD 164816 includes a neutron star born in a
supernova, this supernova should have been very recent and should have given
the system a kick, which is consistent with the observation that the star HD
164816 has a significantly different radial velocity than the cluster mean. In
addition we confirm the binarity of HD 164816 itself by obtaining an orbital
period of 3.82 d, projected masses $m_1 {\rm sin}^{3} i$ = 2.355(69) M$_\odot$,
$m_2 {\rm sin}^{3} i$ = 2.103(62) M$_\odot$ apparently seen at low inclination
angle, determined from high-resolution optical spectra.
