Spitzer Space Telescope - Archive Research Proposal #20547


Meta Analysis on Debris Disks Surveys

Principal Investigator: David Tytler
           Institution: University of California, San Diego

Co-Investigators: 
David Kirkman, University of California, San Diego                    
Charles Beichman, CalTech                                             
Geoffrey Bryden, JPL                                                  

Science Category: circumstellar/debris disks 
Dollars Approved: 68362.0 

Abstract:
We will conduct a comprehensive statistical appraisal of debris dust
disks around normal stars.  We will work with Spitzer MIPS 24 and 70
micron fluxes for 946 stars from 10  programs.  For each star we
compare the observed fluxes with those expected from a model stellar
atmosphere.  Approximately 15% of stars will show excess emission at
70  microns, from dust in debris disks 10  -- 100  AU from the stars.
We will apply survival statistics to estimate the distribution of the
number of stars with a given flux excess.  We will estimate these
distributions separately for stars of different spectral type,
different metallicity and for those with and without planets.
Survival statistics are ideal for this problem because they make full
use of all the information in both the numerous upper limits and the
occasional detections of excess flux.  We will also sum MIPS images of
various groups of 10  -- 100  stars of specific types.  These sums
average over the varying background which is a major source of error
at 70  microns.  For stars with low S/N detections or no detections of
the stellar photospheres at 70  microns, the sums will promote
non-detections into composite detections, with approximately 3 -- 10
times more sensitivity than individual images.