  Using the Herschel PACS and SPIRE FIR/submm data, we investigate variations
in the dust spectral index $\beta$ in the nearby spiral galaxy M33 at a linear
resolution of 160 pc. We use an iteration method in two different approaches,
single and two-component modified black body models. In both approaches,
$\beta$ is higher in the central disk than in the outer disk similar to the
dust temperature. There is a positive correlation between $\beta$ and Halpha as
well as with the molecular gas traced by CO(2-1). A Monte-Carlo simulation
shows that the physical parameters are better constrained when using the
two-component model.
