title: The dust grains from 9P/Tempel 1 before and after the encounter with Deep Impact.
abstract: Gemini-N observed the properties of dust ejected from the nucleus of comet 9P/Tempel 1 before and after its encounter with Deep Impact. Marked changes were seen in the 7.8- to 13-micrometer spectral energy distribution and derived grain properties of the inner coma. A strong, broad silicate feature dominated by emission from amorphous pyroxene, amorphous olivine, and magnesium-rich crystalline olivine had developed by 1 hour after impact. The ejected dust mass is congruent with 10(4) to 10(6) kilograms on the basis of our models. Twenty-six hours later the silicate feature had faded, leaving a smooth featureless spectrum, similar to that observed before the impact, suggesting that the impact did not produce a new active region releasing small particles on the nucleus.
authors.affiliation: Center for Astrophysics and Space Sciences, University of California, San Diego, 9500 Gilman Drive, Department 0424, La Jolla, CA 92093-0424, USA. dharker@ucsd.edu
authors.forename: David E
authors.initials: DE
authors.lastname: Harker
authors.forename: Charles E
authors.initials: CE
authors.lastname: Woodward
authors.forename: Diane H
authors.initials: DH
authors.lastname: Wooden
mesh_terms: D019443:Cosmic Dust; D019110:Meteoroids; D009930:Organic Chemicals / Q000032:analysis; D017640:Silicates; D013055:Spectrophotometry, Infrared
chemical_list: D019443:Cosmic Dust; D009930:Organic Chemicals; D017640:Silicates