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		| Paper: | Quantifying the Gas Inside Dust Cavities in Transitional Disks: Implications for Young Planets |  
		| Volume: | 499, Revolution in Astronomy with ALMA: The Third Year |  
		| Page: | 281 |  
		| Authors: | van Dishoeck, E. F.; van der Marel, N.; Bruderer, S.; Pinilla, P. |  
		| Abstract: | ALMA observations of a small sample of transitional disks with large   dust cavities observed in Cycle 0 and 1 are summarized. The gas and   dust surface density structures are inferred from the continuum and   12CO, 13CO and C18O line data using the DALI   physical-chemical code. Thanks to its ability to self-shield, CO can   survive inside dust cavities in spite of being exposed to intense UV   radiation and can thus be used as a probe of the gas   structure. Modeling of the existing data shows that gas is present   inside the dust cavities in all cases, but at a reduced level   compared with the gas surface density profile of the outer disk. The   gas density decrease inside the dust cavity radius by factors of up   to 104 suggests clearing by one or more planetary-mass   companions. The accompanying pressure bumps naturally lead to   trapping of the mm-sized dust grains observed in the ALMA images. |  
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