  It is shown in a recent preprint [arXiv:2001.10008] that the central spin
model with XX-type qubit-bath coupling is integrable for a central spin
$s_0=1/2$. Two types of eigenstates, separable states (dark states) and
entangled states (bright states) between the central spin and the bath spins,
are manifested. In this work, we show by using an operator product state
approach that the XX central spin model with central spin $s_0>1/2$ and
inhomogeneous coupling is partially solvable. That is, a subset of the
eigenstates are obtained by the operator product state ansatz. These are the
separable states and those entangled states in the single-spin-excitation
subspace with respect to the fully polarized reference state. Due to the high
degeneracy of the separable states, the resulting Bethe ansatz equations are
found to be non-unique. In the case of $s_0=1/2$ we show that all the separable
and entangled states can be written in terms of the operator product states,
recovering the results in [arXiv:2001.10008]. Moreover, we also apply our
method to the case of homogeneous coupling and derive the corresponding Bethe
ansatz equations.
