  With a hyperbolic trajectory around the Sun, `Oumuamua is the first confirmed
interstellar object. However, its origin is poorly known. By simulating the
orbits of 0.23 million local stars, we find 109 encounters with periastron less
than 5 pc. `Oumuamua's low peculiar velocity is suggestive of its origin from a
young stellar association with similar velocity. In particular, we find that
`Oumuamua would have had slow encounters with at least five young stars
belonging to the Local Association thus suggesting these as plausible sites for
formation and ejection. In addition to an extremely elongated shape, the
available observational data for `Oumuamua indicates a red colour suggestive of
a potentially organic-rich and activity-free surface. These characteristics
seem consistent with formation through energetic collisions between planets and
debris objects in the middle part of a young stellar system. We estimate an
abundance of at least 6.0$\times10^{-3}$ au$^{-3}$ for such interstellar
objects with mean diameter larger than 100 m and find that it is likely that
most of them will be ejected into the Galactic halo. Our Bayesian analysis of
the available light curves indicates a rotation period of
$6.96_{-0.39}^{+1.45}$ h which is consistent with the estimation by Meech et
al. 2017 and shorter than other literature. The codes and results are available
on https://github.com/phillippro/Oumuamua.

Earth and Planetary Astrophysics;Solar and Stellar Astrophysics