Updated PDF File Assigned ID: 401 ----- Attempting Submission 1 (Fri Feb 25 16:13:03 GMT 2011) ----- HST Phase I Proposal 401 (cchen_polarimetry.apt) successfully submitted. ----- Attempting Submission 2 (Fri Feb 25 20:05:29 GMT 2011) ----- HST Phase I Proposal 401 (cchen_polarimetry.apt) successfully submitted. ----- Attempting Submission 3 (Fri Feb 25 20:14:20 GMT 2011) ----- HST Phase I Proposal 401 (cchen_polarimetry.apt) successfully submitted. ----- Attempting Submission 4 (Fri Feb 25 23:30:44 GMT 2011) ----- HST Phase I Proposal 401 (cchen_polarimetry.apt) successfully submitted. ----- Attempting Submission 5 (Sat Feb 26 03:12:58 GMT 2011) ----- We propose to conduct an HST archival study of NICMOS coronagraphic polarimetry data for 7 well-studied debris disks that have been spatially resolved in scattered light. We plan to measure the phase function and polarization fraction to (1) characterize the size and porosity of constituent dust grains, (2) determine whether the circumstellar grains are more similar to porous aggregates released from comets or compact grains generated by collisions among asteroids, and (3) search for broad trends in grain properties that are expected based on parent body temperatures and grain dynamics. Since many of the systems are also imaged in thermal emission and possess well-measured SEDs, we also propose to conduct a multi-wavelength analysis to ensure that our conclusions are robust. HST NICMOS polarimetry of spatially resolved debris disks (with well constrained geometries) provides a unqiue opportunity to derive high quality Stokes I, Q, and U maps that will be challenging to surpass from the ground.

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