Spitzer Space Telescope - General Observer Proposal #20363


Grain Settling and Growth in the Planet Formation Region of Disks

Principal Investigator: John Carr
           Institution: Naval Research Laboratory

Co-Investigators: 
Joan Najita, National Optical Astronomy Observatory                   

Science Category: circumstellar/debris disks 
 Observing Modes: IrsStare 
  Hours Approved: 12.0 

Abstract:
We propose to measure the gas-to-dust ratio in a sample of
protoplanetary disk atmospheres in order to determine the amount of
grain settling and growth at planet formation distances.  These
processes are a basic and important step in the planet formation
process, but direct evidence for them is lacking for the inner disk (<
10  AU).  High-resolution IRS spectra of classical T Tauri stars will
be obtained to measure the gas content using molecular and atomic
diagnostics in the MIR.  By modeling the gaseous emission spectra
along with IRS low-resolution spectra of dust emission features and
continuum, we will be able to determine the gas and dust columns and
grain sizes, and constrain the amount of both grain settling and
growth in disk atmospheres.