Contributions to the kinematics of type I tails of comets

Wurm, K.; Mammano, A.

doi:10.1007/bf00645393

Cited by 33 publications

(6 citation statements)

References 2 publications

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“…If the ion production rate were drastically reduced on a short timescale (less than an hour), the ionosphere of the comet could shrink temporarily and allow the magnetic field lines to slip away. The change of ionization rate in the comet could be strongly influenced by a change in the solar UV radiation or in the density of neutrals out of which the ions are created [Wurm and Mammano, 1972].…”

Section: Ion Production Effectsmentioning

confidence: 99%

Global magnetohydrodynamic simulation of a comet crossing the heliospheric current sheet

Yi¹,

Walker²,

Ogino³

et al. 1996

J. Geophys. Res.

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A disconnection event (DE) of the plasma tail is one of the most spectacular phenomena observed in comets. Yet it has remained an important unsolved problem in planetary astronomy and space physics. The solar wind is thought to play a major role in the creation of comet plasma tail DEs. Comparison of the solar wind conditions and 16 DEs in Halley's comet shows that DEs are associated primarily with crossings of the heliospheric current sheet (HCS) and apparently not with any other properties of the solar wind, such as high‐speed streams [Yi et al., 1994]. In order to present a mechanism that explains the DE in terms of the local conditions at the comet, a three‐dimensional resistive compressible magnetohydrodynamic (MHD) simulation was carried out to test the effect of the HCS crossing on the comet plasma tail dynamics. We have focused on the fact that the thickness of the HCS is about 10,000 km [Winterhalter et al., 1994], which was neglected in the previous simulations. Such a narrow discontinuity cannot be described by a global simulation using large grid cells, due to the intrinsic numerical diffusion in the system. Therefore, we have used an approximation to calculate the induced current across the HCS when it is compressed inside the cometosheath. This produces results different from previous simulations. However, they satisfy all the observational constraints. The results show that frontside magnetic reconnection between the reversed interplanetary magnetic fields [Niedner and Brandt, 1978] can reproduce the evolution morphology of a DE, including ray formation, when a comet crosses the HCS. This supports the association of DEs with HCS crossings.

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Section: Ion Production Effectsmentioning

confidence: 99%

Global magnetohydrodynamic simulation of a comet crossing the heliospheric current sheet

Yi¹,

Walker²,

Ogino³

et al. 1996

J. Geophys. Res.

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“…While the cometary tail rays ultimately align close to the antisolar direction, they apparently first appear at large angles with respect to that direction, sometimes in the solar direction, and then fold back toward the antisolar direction. Wurm and Mammano [1972] argue that all the shifts and motions of the rays are not necessarily in response to solar wind flow conditions but are caused by [1981] has suggested that bubbles of continuum radiation escape from the downstream tail in bubbles of solar wind plasma. The solar wind would convect the disconnected fragment in a more-or-less antisunward direction, but motion in the azimuthal direction may be due to pressure gradients transverse to the radial direction.…”

Section: Implications Of Distant Magnetotail Encountersmentioning

confidence: 99%

Voyager observations of Jupiter's distant magnetotail

Kŭrth¹,

Gurnett²,

Scarf³

et al. 1981

J. Geophys. Res.

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Observations of nonthermal continuum radiation by Voyager 1 and 2 at large distances from Jupiter have led to the identification of brief encounters with the Jovian magnetosphere at distances greater than 700 RJ and in directions substantially far from the Jupiter‐sun line. In addition, a number of examples of continuum radiation apparently trapped in local density depressions in the solar wind are observed. Simultaneous measurements by the Voyager plasma instrument have verified the distant magnetotail crossings and are used to correlate the occurrence of trapped continuum radiation events within solar wind density rarefactions. The Voyager observations of the distant Jovian magnetotail are compared with observations in the distant terrestrial magnetosphere and also with observations of the plasma tails of comets. Viable explanations of the observations are that the Jovian tail consists of filamentary structures, some of which extend to large distances in the predawn direction, or that the Jovian tail may be offset in the dawn direction by a combination of corotation angular momentum and forces associated with high‐speed streams in the solar wind. The observations of continuum radiation trapped in low‐density regions of the solar wind suggest that Voyager may at times be connected to the distant tail by a low‐density trough which acts as a wave guide and allows radiation from the tail to reach the spacecraft. This may provide an indirect method of detecting the tail extending more than 2 AU downstream from Jupiter.

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“…The rays in thLs second part of the ion tail are undisturbed except for a small displacement of some rays near the kink. The angle between these two parts is about 25 0 (Wurm and Mammano, 1972 We are interested in investigating the relation between this kink and solarwind conditions.…”

Section: Comet Observationsmentioning

confidence: 99%

Solar wind interaction with Comet Bennett (1969i)

et al. 1973

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This paper examines the relations between the solar-wind and Comet Bennett during the period March 23 to April 5, 1970. A large kink was observed in the ion tail of the comet on April 4, but no solarwind stream was observed in the ecliptic plane which could have caused the kink. Thus, either there was no correlation between the solar wind at the earth and and that at Comet Bennett (which was 40 0 above the ecliptic) or the kink was caused by something other than a high-speed stream.The fine structure visible in photographs of the kink favors the second of these alternatives. It is shown that a shock probably passed through Comet Bennett on March 31, but no effect was seen in ph~tographs of the comet.A stream preceded by another shock and a large ab~upt change in momentum flux might have intercepted the comet between March 24 and March 28, but again no effect was seen in photogr~ph~of the Comet. In view of these results, one must seriously consider the possibility that a large, abrupt change in momentum flux of the solar-wind is neither necessary nor sufficient to cause a large kink in a comet tail.

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Contributions to the kinematics of type I tails of comets

Cited by 33 publications

References 2 publications

Global magnetohydrodynamic simulation of a comet crossing the heliospheric current sheet

Global magnetohydrodynamic simulation of a comet crossing the heliospheric current sheet

Voyager observations of Jupiter's distant magnetotail

Solar wind interaction with Comet Bennett (1969i)

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