Activity of Comet C/2006 W3 Christensen

• Published in: Icarus (New York, N.Y. 1962) N.Y. 1962), 2015-04, Vol.250, p.595-601
• Main Authors: Kossacki, Konrad J., Szutowicz, Slawomira
• Format: Article
• Language: English
• Subjects: Carbon monoxide; Comet nuclei; Comets; Comets, composition; Emission; Fluxes; Grains; Ices; Mathematical models; Perihelions
• ISSN: 0019-1035; 1090-2643
• DOI: 10.1016/j.icarus.2014.12.019

•We simulated evolution of a model nucleus orbiting like Comet C/2006 W3.•The simulated fluxes of H2O and CO were fitted to the data.•The agreement was possible only including sublimation from rejected grains.•Active surface can be very small, less than 10square km. Emission of volatiles for the long-period Comet C/2006 W3 Christensen was observed before perihelion from 3.7AU through perihelion passage at 3.13AU till 5.0AU after perihelion. Coma is found to be strongly enriched in molecules more volatile than water. At heliocentric distances 3.13–3.7AU activity of the comet was mostly driven by CO emission (Bockelée-Morvan, D., et al. [2010]. Astron. Astrophys. 518, L149; Ootsubo, T., et al. [2012]. Astrophys. J. 752, id15). However, emission of water was observed as far as at 5AU. We attempted to determine, what composition and structure of the nucleus are needed to reproduce the observed strong emission of CO molecules. For this purpose we simulated evolution of a model nucleus orbiting like Comet C/2006 W3. We fitted simulated profiles of fluxes of molecules to the described in literature fluxes derived from observations (Bockelée-Morvan, D., et al. [2010]. Astron. Astrophys. 518, L149; Ootsubo, T., et al. [2012]. Astrophys. J. 752, id15; de Val-Borro, M., et al. [2014]. Astron. Astrophys. 564, A124). The agreement was possible only using model taking into account sublimation from ejected grains. We have found, that the nucleus should be very porous, composed of moderately fine grains, about 10μm in diameter, and have tensile strength about 10kPa, like estimated for Comet 9P/Tempel 1.