  The STAR experiment at RHIC is carrying out a comprehensive high-energy spin
physics program to understand the internal structure and dynamics of the proton
in polarized proton-proton collisions at $\sqrt{s} = 200$ GeV and $\sqrt{s} =
500/510$ GeV. STAR has the capability, with nearly full azimuthal coverage, to
reconstruct leptons, hadrons and jets in the mid-rapidity region ($|\eta|<1$).
The results for inclusive jet longitudinal double spin asymmetries taken during
the 2009 RHIC run indicate the first non-zero gluon contribution ($\Delta
g(x,Q^{2}) / g(x,Q^{2})$) to the proton spin for $0.05<x<1$ (Bjorken-x:
momentum fraction of partons). Recent longitudinal single-spin asymmetry
measurements of $W^{+/-}$ bosons at $\sqrt{s} = 500/510$ GeV in polarized
proton-proton collisions provide a direct probe of the polarized anti-u and
anti-d quark distributions ($\Delta \bar{u}(x,Q^{2})$, $\Delta
\bar{d}(x,Q^{2})$). These results better constrain the polarized gluon and sea
quark distributions of the proton in the RHIC sensitive kinematic region.
Future measurements with continuing high energy polarized proton-proton run at
RHIC and detector upgrade will explore the gluonic contribution to the proton
spin in extended range.
