  We report the discovery of a dark companion to 2MASS J15274848+3536572 with
an orbital period of 6.14 hr. Combining the radial velocity from LAMOST
observations and modelling of the multiband light curve, one obtains a mass
function of $\simeq 0.131~\rm M_{\odot}$, an inclination of
$45.20^\circ{}^{+0.13^{\circ}}_{-0.20^{\circ}}$, and a mass ratio of
$0.631^{+0.014}_{-0.003}$, which demonstrate the binary nature of the dark
companion with mass of $0.98 \pm 0.03\rm M_{\odot}$ and a main-sequence K9-M0
star of $0.62 \pm 0.01~\rm M_{\odot}$. LAMOST optical spectra at a range of
orbital phases reveal extra-peaked Halpha emission that suggests the presence
of an accretion disk. The dark companion does not seem to be a white dwarf
because of the lack of any observed dwarf nova outbursts in the long-term data
archive, although a magnetic white dwarf cannot be excluded. Alternatively, we
propose a scenario wherein the dark companion is a neutron star, but we have
not detected radio pulsations or a single pulse from the system with the FAST
(Five-hundred-meter Aperture Spherical radio Telescope), which hints at a
radio-quiet compact object. If the dark companion is identified as a neutron
star, it will be the nearest ( ~ 118 pc) and lightest neutron star.
Furthermore, a kinematic analysis of the system's orbit in the galaxy may
suggest its supernova event is associated with the radionuclide $^{60} \rm Fe$
signal observed from the deep-sea crusts. This radio-quiet and X-ray-dim nearby
neutron star may resemble an XDINS (X-ray-dim isolated neutron star), but in a
binary.
