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Variation In The Dust Spectral Index Across M33, Fatemeh S. Tabatabaei, Jonathan Braine, Carsten Kramer, Manolis Xilouris, Mederic Boquien, Simon Verley, Eva Schinnerer, Daniela Calzetti, Francoise Combes, Frank Israel, Christian Henkel, The Herm33es Team

Daniela Calzetti

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 …