  We study the critical behavior for inhomogeneous versions of the Curie-Weiss
model, where the coupling constant $J_{ij}(\beta)$ for the edge $ij$ on the
complete graph is given by $J_{ij}(\beta)=\beta w_iw_j/(\sum_{k\in[N]}w_k)$. We
call the product form of these couplings the rank-1 inhomogeneous Curie-Weiss
model. This model also arises (with inverse temperature $\beta$ replaced by
$\sinh(\beta)$) from the annealed Ising model on the generalized random graph.
We assume that the vertex weights $(w_i)_{i\in[N]}$ are regular, in the sense
that their empirical distribution converges and the second moment converges as
well. We identify the critical temperatures and exponents for these models, as
well as a non-classical limit theorem for the total spin at the critical point.
These depend sensitively on the number of finite moments of the weight
distribution. When the fourth moment of the weight distribution converges, then
the critical behavior is the same as on the (homogeneous) Curie-Weiss model, so
that the inhomogeneity is weak. When the fourth moment of the weights converges
to infinity, and the weights satisfy an asymptotic power law with exponent
$\tau$ with $\tau\in(3,5)$, then the critical exponents depend sensitively on
$\tau$. In addition, at criticality, the total spin $S_{N}$ satisfies that
$S_{N}/N^{(\tau-1)/(\tau-2)}$ converges in law to some limiting random variable
whose distribution we explicitly characterize.
