Cool Stars 14 - Submitted Abstract # 377
This version created on 05 October 2006

Spitzer Galactic First Look Survey Studies of the Incidence of Dust
Around Field Stars


Sergio Fajardo-Acosta, Caltech Spitzer Science Center
Ian McNabb, University of Denver
Susan Stolovy, Caltech Spitzer Science Center

We investigate the frequency of occurrence of mid-infrared excess
emission from dust around field stars in the Galaxy.  We examine the
incidence of excesses and dust temperatures per stellar spectral type.
The SEDs of the systems let us study the dust distribution around
them, such as inferring the presence or absence of inner "holes" in
them.  The observational data consist of Spitzer Space Telescope IRAC
3.6, 4.5, 5.8, 8 micron, and MIPS 24 micron photometry obtained in the
Galactic First Look Survey.  We merged these data with 2MASS J, H, and
Ks photometry, and constructed 1.25--24 micron SEDs of ~8,000  stars.
We fitted Kurucz photospheric models to these SEDs, in order to assess
and study excess emission.  We find that < 1% of these stars show
excesses at IRAC 8 micron or shorter wavelengths, thus indicating hot
dust (~400  K) around them.  We also find that ~10% of stars with MIPS
24 micron detections have excess emission at 24 micron, indicating
warm dust (~100  K) around them.  These studies shed light on how
frequent planetary formation is in the Galaxy.  This work is based on
observations made with the Spitzer Space Telescope, which is operated
by JPL, Caltech under NASA contract 1407.  

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