Spitzer Space Telescope - General Observer Proposal #20707


Investigation of the Vega phenomenon among F-type stars of known
infrared excess

Principal Investigator: Peter Abraham
           Institution: Konkoly Observatory of the Hungarian Academy of Sc

Co-Investigators: 
Attila Moor, Konkoly Observatory                                      
Daniel Apai, University of Arizona                                    
Carol Grady, Eureka Scientific, NASA GSFC                             
Thomas Henning, Max-Planck-Institut fur Astronomie                    
Csaba Kiss, Konkoly Observatory                                       
Ilaria Pascucci, University of Arizona                                

Science Category: circumstellar/debris disks 
 Observing Modes: IrsStare MipsPhot 
  Hours Approved: 35.1 

Abstract:
One of the main discoveries of the IRAS mission was that main-sequence
stars can be accompanied by circumstellar dust disks (Vega
phenomenon).  In this proposal we investigate a sample of 62 Vega
candidate stars, whose infrared excess above the photosphere -
indication for the presence of a disk - was in most cases already
measured by ISO or IRAS.  All stars are in the spectral range of
F0-F9, resulting in a rather homogeneous sample in terms of stellar
mass and luminosity.  On the basis of IRS and MIPS observations, we
study (i) the temporal evolution of debris disks, focusing on the
evolution of the geometrical structure of the disk and of grain
processing of the disk material;  (ii) individual systems with very
high fractional luminosity;  (iii) old stars with warm debris disks;
and (iv) debris disks in young moving groups.  Our results will be
used to verify model predictions for F stars, and they can also be
compared with the outcome of similar programs dedicated to A- and
G-type stars.