The effect of local optically thick regions in the long-wave emission of young circumstellar disks L. Ricci, F. Trotta, L. Testi, A. Natta, A. Isella and D. J. Wilner A&A, 540 (2012) A6 Published online: 14 March 2012 DOI: 10.1051/0004-6361/201118296