31st Annual Meeting of the DPS, October 1999
Session 17. Comet Comae Posters
Poster Group I, Monday-Wednesday, October 11, 1999, , Kursaal Center

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[17.17] Dust Coma Simulations: Grains Fragmentation or Fading Grains?

L.M. Lara (Sci-SO at SSD, ESTEC-ESA, The Netherlands), P.J. Gutierrez (IAA-CSIC, Spain), R. Schulz (Sci-SO at SSD, ESTEC-ESA, The Netherlands), J.A. St\"uwe (Astronomisches Institut, Ruhr-Universi\"at Bochum, Germany), G.P. Tozzi (Osservatorio Astrofisico di Arcetri, Italy)

Comet C/1996 Q1 (Tabur) was observed during Sept. 12-17, 1996 (\rm rh=1.2, \Delta=0.75) shortly after its discovery. The investigation of the dust in the Sun-comet direction leads to evidence of fading grains in this comet. The continuum brightness profiles can be adequately fitted with a linear approach (m=1 in the log B-log \rho representation) at projected distances from the nucleus (\rho) greater than 3500 km. However, at small distances, the linear fits for the Sunward profiles require slopes much higher than 1. Further analysis of the dust color firmly indicates the existence of a large change of color that can be interpreted by fading grains in this comet. The continuum brightness profiles in Sun and tail direction have been simulated by means of (i) a Fibson & Probstein model and (ii) a Montecarlo model. The model assumes different grain distribution and/or refractive index as a function of \rho to reproduce the progressive fragmentation and/or ice sublimation of the grains.

The author(s) of this abstract have provided an email address for comments about the abstract: llara@estec.esa.nl

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