The Electrodynamics of Charged Dust in the Cometary Environment

Abstract

Dust in the plasma and radiative environment of a comet is necessarily electrically charged. This charging has both physical and dynamical effects on the dust, being particularly important on the smallest particles observed in the dust size spectrum. In this paper, these dynamical effects are reviewed and the pertinent observations are discussed.

The Nucleus of Comet Hyakutake (C/1996 B2)

“…In the regions outside the jet and tail, n = 1.1-1.2, suggesting an emissivity decreasing with distance, most probably due to grain evaporation. Another possible cause of variations in n is the effect of radiation pressure on 1/ρ outflow; however, had this been the dominant effect, we would have expected from a simple fountain model (Horanyi and Mendis 1991) …”

Dusty Plasma Effects in Comets: Expectations for Rosetta

“…[43] In space, comets that exhibit both dust and plasma tails with significant overlap provide excellent laboratories for the study of the consequences of dust-plasma interactions, and several cometary phenomena have been explained on the basis of electrostatic disruption of dust [Horányi and Mendis, 1991]. Among these is an interesting class of phenomena observed in several comets, first discussed, in some detail, by Sekanina [1976] and subsequently by Sekanina and Farrell [1980], in connection with comet West 1976 V1.…”

“…These authors suggested that these dust packets resulted from the break-up of larger composite grains, that left the nucleus and eventually coming unglued. Horányi and Mendis [1991] suggested that such a process of ungluing, presumably due to the sublimation of a volatile icy glue holding the less volatile dust grains together, would be more a gradual process than was implied by those short discrete events. They suggested, as an alternative, that such fragile composite dust aggregates could be electrostatically disrupted in the regions where they were seen; i.e., outside the ionopause where substantial electrostatic potentials of | | 10 -20 V may be achieved.…”

“…(3) Figure 6. The apex distance of the bounding paraboloid for uncharged Olivine (upper curve) and Magnetite (lower curve) grains as a function of grain size [Horányi and Mendis, 1991]. [48] The values of Ä for Olivine and Magnetite are given in Table 1, taking | (V)| = 5.…”

“…20005 Paper number 2012RG000422 (EPOXI, 2010); and (e) 9P/Tempel 1 (Deep Impact, 2004 andStardust, 2011). and the Vega 1 and 2, and Giotto spacecraft fly-bys (on the sunward side) of comet Halley in 1986 [Mendis, 1988;Horányi and Mendis, 1991]. Subsequent fly-by missions ( Figure 1) have focused on the cometary nucleus and provided more details of the surface properties of four more comets [Weaver, 2004;A'Hearn et al, 2005;Brownlee et al, 2006;Hartogh et al, 2011].…”