Spitzer Space Telescope - General Observer Proposal #50403


Mind the Gap: Timing Planet Formation by Looking in the Holes and Gaps of Dusty
Disks

Principal Investigator: Nuria Calvet
           Institution: University of Michigan

     Technical Contact: Catherine Espaillat, University of Michigan

Co-Investigators: 
Catherine Espaillat, University of Michigan                           
James Muzerolle, University of Arizona                                
Dan Watson, University of Rochester                                   
Lee Hartmann, University of Michigan                                  
Elise Furlan, UCLA/NAI                                                

Science Category: circumstellar/debris disks 
 Observing Modes: IrsStare 
  Hours Approved: 5 

Abstract:
Uncovering the details of disk dissipation is critical to understanding the
formation of planetary systems. In the past few years Spitzer has greatly aided
in this task by giving us an unprecedented view of dust clearing in the inner
regions of protoplanetary disks, most notably through observations of stars with
inner disks that are mostly devoid of small dust i.e. the "transitional disks."
Recently, Spitzer has identified a new class of "pre-transitional disks" with
significant near-infrared excesses which indicate the presence of an optically
thick inner disk separated from an optically thick outer disk, suggesting the
incipient development of disk gaps as opposed to the inner holes seen in
transitional disks. Here we propose for five hours of IRS time to study
variability in 18 transitional and pre-transitional disks in Taurus and
Chamaeleon in order to refine planet formation theories. The prospect of
detecting variability in these objects is favorable based on IRS data taken in
the past few weeks showing that transitional disks exhibit extreme variability
due to the behavior of optically thin dust within the inner disk hole.
Variability in transitional and pre-transitional disks can be linked with
planets interacting with dust in the holes and gaps of these disks and therefore
this study will help provide estimates of spatial inhomogeneities and
characteristic timescales of changes for planet formation models.