Name/Affiliation: Carlo Felice Manara (European Southern Observatory)
On the gas content of transitional disks: a VLT/X-Shooter study of accretion and winds
Transitional disks are thought to be a late evolutionary stage of protoplanetary disks whose inner regions have been depleted of dust. The mechanism responsible for this depletion is still under debate. To constrain the various models proposed to explain this phase it is mandatory to have a good understanding of the properties of the gas content in the inner part of the disk. Using the VLT/X-Shooter spectrograph, which is a broad band - UV to NIR - medium resolution instrument, we derive the stellar, accretion, and wind properties of a sample of 22 transitional disks. The analysis of these properties allows us to put strong constraints on the gas content in a region very close to the star (< 0.2 AU) which is not accessible with any other observational technique. With a self-consistent technique we derive mass accretion rates and wind properties of all the targets. The accretion rates and wind properties of 80% of the transitional disks in our sample are comparable to those of classical TTauri stars. Even considering the incompleteness of our sample, this shows that there are (at least) some transitional disks with accretion properties compatible with those of classical TTauri stars. Only in 2 cases the mass accretion rates are much lower, while the wind properties remain similar. We do not see any strong trend of the mass accretion rates with the size of the dust depleted cavity, nor with the presence of a dusty optically thick disk very close to the star. These results suggest that the inner disk of the strongly accreting transitional disks in our sample is still gas-rich. Here we present the results of this work.