  A complete realistic study of $_\Lambda ^5$He hypernucleus is presented using
a realistic Hamiltonian and wave function. This study takes into account all
relevant dynamical correlations along with $\Lambda N$ space-exchange
correlation (SEC). We also compute $\Lambda NN$ force and the corelation
induced by this force. The SEC affects the central repulsive $\lambda N$
correlation significantly at $r \le 2.0$ fm, specially at its peak and in its
vicinity. SEC significantly affects energy breakdown of the hypernucleus,
$\Lambda$-seperation energy, nuclear core (NC) polarization and density
profiles. A lage NC polarization is found with and without SEC, respectively.
The SEC effect is relatively large in two-pion exchange component of $\Lambda
NN$ force. Therefore, any attempt to pin down the strength of this force with
no SEC would be flawed.
