Spitzer Space Telescope - General Observer Proposal #80187


The Lifetime of Circumstellar Disks Around Low-Mass Brown Dwarfs

Principal Investigator: Kevin Luhman
           Institution: Pennsylvania State University

     Technical Contact: Kevin Luhman, Pennsylvania State University

Science Category: brown dwarfs/very low mass stars 
 Observing Modes: IRAC Post-Cryo Mapping
  Hours Approved: 3.5 

Abstract:
The lifetimes of optically thick accretion disks around young stars are
important because they represent a limit on the amount of time available for the
formation of giant planets. Estimating disk lifetimes as a function of stellar
mass requires measurements of disk fractions for samples of stars that cover a
wide range of ages and masses. Previous photometric surveys with Spitzer have
explored much of this phase space. However, one area that has relatively few
disk fraction measurements is the least massive brown dwarfs at >3 Myr (<0.03
Msun). Therefore, we propose to measure IRAC photometry for the least massive
known brown dwarfs in the Upper Sco association (5 Myr). We will use the IRAC
data to measure the disk fraction in this sample, which will then be combined
with disk fractions previously measured with Spitzer in younger regions to
estimate the typical lifetimes of disks around the smallest brown dwarfs.