ISM -- Oral Presentation

Spitzer measurements of mid-infrared extinction in infrared-dark clouds

Sean Carey, Spitzer Science Center / Caltech

Russell O. Redman (HIA/NRC Canada), Lori E. Allen (Harvard-Smithsonian CfA), Joseph L. Hora (Harvard-Smithsonian CfA)

Infrared dark clouds are dense molecular cores which have been identified as absorption objects in mid-infrared surveys of the Galactic plane. As such they are ideal objects to use in measuring the mid-infrared extinction curve. We present Spitzer and MSX observations of the mid-infrared extinction profiles of three infrared-dark clouds. The extinction is estimated from the diffuse mid-infrared background instead of more traditional stellar reddening measurements due to the low number of observed background objects and relatively large number of embedded protostars. We will compare the spatial profile of the extinction to column density estimates from submillimeter continuum observations of the dust. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under NASA contract 1407. Support for this work was provided by NASA through contract 1256790 issued by JPL/Caltech.