Comets

Festou, M. C.; Rickman, H.; West, R. M.

doi:10.1007/bf00872944

Cited by 73 publications

(37 citation statements)

References 215 publications

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“…Specifically, the phenomena we have in mind are shocks (Festou et al 1993;Zilbersher et al 1998;Pouquet et al 1999) and localized oscillations, as well as the spatio-temporal intermittency events present in the interstellar medium and in the solar corona, or more generally in the heliosphere (Burlaga 1991;Schwenn and Marsch 1991), of which solar flares are but a catastrophic example (Galtier and Pouquet 1998); here the 1D reduction proves to be rich enough to capture the physics and mathematics of the phenomena. On the other hand, in some other cases, this reduction is the last resort, given the formidable task presented both mathematically and numerically by the full 3D-MHD problem.…”

Section: Aim and Scope Of This Studymentioning

confidence: 99%

Meromorphy and topology of localized solutions in the Thomas–MHD model

Fournier

Galtier

2001

J. Plasma Phys.

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Abstract. The one-dimensional MHD system first introduced by J.H. Thomas [Phys. Fluids 11, 1245(1968] as a model of the dynamo effect is thoroughly studied in the limit of large magnetic Prandtl number. The focus is on two types of localized solutions involving shocks (antishocks) and hollow (bump) waves. Numerical simulations suggest phenomenological rules concerning their generation, stability and basin of attraction. Their topology, amplitude and thickness are compared favourably with those of the meromorphic travelling waves, which are obtained exactly, and respectively those of asymptotic descriptions involving rational or degenerate elliptic functions. The meromorphy bars the existence of certain configurations, while others are explained by assuming imaginary residues. These explanations are tested using the numerical amplitude and phase of the Fourier transforms as probes of the analyticity properties. Theoretically, the proof of the partial integrability backs up the role ascribed to meromorphy. Practically, predictions are derived for MHD plasmas.

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Section: Aim and Scope Of This Studymentioning

confidence: 99%

Meromorphy and topology of localized solutions in the Thomas–MHD model

Fournier

Galtier

2001

J. Plasma Phys.

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“…Comet observers have supposed that the relative strengths of the O( 1 S → 1 D) and O( 1 D → 3 P) green (557.7 nm) and red (630.0 nm) lines can be used to infer the relative abundance of water and carbon dioxide in cometary coma (Delsemme 1980;Festou 1981;Festou and Feldman 1981;Huebner 1985;Cochran and Cochran 2001;Capria et al 2005Capria et al , 2008. Laboratory measurements have determined the yield of O( 1 D) from photodissociation of water, but none of these experiments would have been capable of detecting O( 1 S).…”

Section: Absorption Cross Sections and Excited Photofragment Yields Fmentioning

confidence: 99%

Cross Sections and Reaction Rates for Comparative Planetary Aeronomy

et al. 2008

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“…The theory was subsequently improved by many others such as the Russian astronomer Feodor A. Bredikhin (see e.g. Festou et al 1993). Using this mechanical theory, Finson & Probstein (1968a) presented a method to derive information on the size distribution, production rate, and size-and time-dependent velocities of the grains leaving the inner coma.…”

Section: Introductionmentioning

confidence: 99%

The dust tail of Comet C/1999 T1 McNaught-Hartley

Moreno

Lara

López-Moreno

et al. 2003

A&A

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Abstract.A numerical method to compute cometary dust tail brightnesses has been developed. The method, analogous in many ways to the inverse Monte Carlo method proposed by Fulle (1989), has been applied to red continuum images of comet C/1999 T1 McNaught-Hartley obtained by Lara et al. (2002). The time and size dependence of the particle terminal velocities, the size distribution functions, and the dependence with time of the power index of the size distribution have been derived. The best fits to the observed isophote fields are obtained for highly anisotropic dust grain ejection velocities. The power indexes of the time-dependent dust size distributions show small values, particularly shortly after perihelion is reached, in which a minimum of −5.5 in the power index of the size distribution function is found, suggesting the apparition of small particles. Our results are in line with previous results by Fulle (1992) relating a systematic decrease of size distribution power index and dust ejection isotropy as the comet age increases. We also derived the dust mass loss rates and the A f ρ quantity as a function of time, providing evidence that these two quantities do not have to be correlated if the size distribution and the dust ejection velocity are both time-dependent, in accordance with the results by Fulle (2000) for comet 46/P Wirtanen.

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Comets

Cited by 73 publications

References 215 publications

Meromorphy and topology of localized solutions in the Thomas–MHD model

Meromorphy and topology of localized solutions in the Thomas–MHD model

Cross Sections and Reaction Rates for Comparative Planetary Aeronomy

The dust tail of Comet C/1999 T1 McNaught-Hartley

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