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Water in protoplanetary disks

Line flux modeling and disk structure
PhD ceremony:Mr S. Antonellini
When:March 04, 2016
Supervisors:I.E.E. (Inga) Kamp, Prof Dr, prof. dr. M.C. Spaans
Where:Academy building RUG
Faculty:Science and Engineering
Water in protoplanetary disks

Protoplanetary disks are the places in which planets form around young stars. These environments consist of dust and gas mainly in forms of molecules. Simple and abundant molecules such as water, carbon monoxide, ammonia, play an important role in the disk thermal balance, and allow also observers to study these objects. Water is an abundant molecule with a rich spectroscopy in the entire IR spectral regime. It can be used to probe local gas physical conditions from the inner through the outer disk.

Observations of water show often non-detections for still unclear reasons. With this thesis we suggest an explanation based on the physical properties of individual protoplanetary disks, their central star and mid-IR dust spectral features. Finally we investigate the hidden reservoirs of water and other volatile species frozen in the coldest regions of the disk.

We conclude that opacity due to the dust is one of the main causes for the suppression of both mid-IR and far-IR water lines in disks. Disks around more luminouscentral stars from modeling, should have stronger mid-IR water lines, but the stronger continuum produced by the warmer dust buries the lines. We also found that the presence ofstronger mid-IR water line fluxes can be consistent with disks depleted in dust or enhanced in gas abundance in the innermost regions.Finally, time-dependent chemistry is not important in the evolution for the two-dimensional distribution of water and other ices in disks after 100.000 yrs.