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K. Gordon, K. Misselt, J.D. Smith, G. Rieke (Univ. of Arizona), G. Clayton (Louisiana State Univ.), Y. Pendleton (NASA/Ames), D. Whittet (Rensselaer Polytechnic Inst.), T. Snow (Univ. of Colorado)
We have observed a sample of hot, reddened stars with the Spitzer Space Telescope to measure the wavelength dependence of the diffuse interstellar extinction curve from 3-38 micron as a function of environment. The observations include Infrared Spectrograph (IRS) spectra from 5-38 microns, Infrared Array Camera (IRAC) 3-8 micron, IRS blue peakup, and Multiband Imaging Photometer for Spitzer (MIPS) 24 micron photometry. The extinction curves created from these data represent the first accurate measurement of the extinction between 5 and 38 microns along lines of sight which clearly probe dust in the diffuse interstellar medium. A unique and valuable aspect of the this research is the direct measurement of extinction from the UV to the far-IR in the same lines of sight enabling the extension of the empirical CCM relationship into the Spitzer infrared. In addition, dust parameters derived from these extinction curves will be far better constrained than in previous studies where the ultraviolet through mid-IR extinction curves were taken from different sightlines with different environmental conditions. The accurate measurement of the infrared extinction provides valuable constraints on dust grain materials, both from prominent features (eg.,10 micron silicate feature) and continuum extinction measurements as a function of environment [eg. R(V)].
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.