Disconnection Events (DEs) in Halley's Comet 1985–1986:

Brandt, John C.; Caputo, F.; Hoeksema, J. T.; Niedner, M. B.; Yi, Yu; Snow, Martin

doi:10.1006/icar.1998.6030

Cited by 25 publications

(16 citation statements)

References 17 publications

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“…The onsets of DEs calculated in this work, an independent analysis of the observational data, are in good agreement with Brandt et al (1999).…”

Section: Analysis Of Individual Onsets Of Dessupporting

confidence: 82%

“…Voelzke, e-mail: mvoelzke@astro.uni-bonn.de that comet P/Halley had just crossed the interplanetary magnetic field (IMF) sector boundary; the solar wind density was, respectively, 15 cm −3 and 7 cm −3 ; the solar wind speed was, respectively, 370 km s −1 and 500 km s −1 . We conclude that our results corroborate the idea that DEs are associated with sector boundary crossings and that the magnetic reconnection plays an important role in the formation of DEs and can be considered as the triggering mechanism (Niedner & Brandt 1978;Brandt et al 1999). …”

supporting

confidence: 88%

“…Yi et al (1993) considered the possible association of changes in the Alfvén Mach number with DEs and concluded that such an association was unlikely. The coronal mass ejection data in Solar Geophysical Data (Wagner 1984) are also not supportive of a correlation between the interplanetary shocks and DEs (Yi et al 1994a;Brandt et al 1999).…”

Section: Analysis Of Individual Onsets Of Desmentioning

confidence: 82%

“…In order to minimize the impact of uncertainties in any single event, Brandt et al (1999) analysed the comet P/Halley DEs as a group for correlation with solar wind features. Their results confirm that the DEs are associated with crossings of the heliospheric current sheet.…”

Section: Analysis Of Individual Onsets Of Desmentioning

confidence: 99%

“…Many ideas were suggested to explain the cyclic phenomena of DEs (Brandt 1990). The current competitive theories to explain the onset of DEs can be grouped into three classes based on the triggering mechanisms: (a) Ion production effects (Wurm & Mammano 1972), (b) Pressure effects (Ip & Mendis 1978;Ip 1980;Jockers 1985;Wegmann 1995;Wegmann 1998), and (c) Magnetic reconnection (Niedner & Brandt 1978;Russell et al 1986;Brandt et al 1992c;Yi et al 1996;Yi et al 1998;Brandt et al 1999). In this work the comet P/Halley DEs are interpreted in terms of the location of the magnetic sector boundaries derived from solar magnetic field data on the "source-surface" (Hoeksema et al 1983) and the expansion of the solar wind.…”

Section: Introductionmentioning

confidence: 99%

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The onsets of disconnection events of comet P/Halley on 1985 December 13-14 and 1986 February 22

Voelzke

Matsuura

2000

Astron. Astrophys. Suppl. Ser.

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Abstract. This work compares cometary and solar wind data with the purpose of determining the solar wind conditions associated with comet plasma tail disconnection events (DEs). The cometary data are from The International Halley Watch Atlas of Large-Scale Phenomena (Brandt et al. 1992a). A systematic visual analysis of the atlas images (Voelzke & Matsuura 1998) revealed, among other morphological structures, 47 DEs. The solar wind data are in situ measurements from IMP-8, ICE and PVO, which are used to construct the variation of solar wind speed, density and dynamic pressure during the analysed interval. Data from these same spacecraft plus Vega 1 were used to determine the times of current sheet crossings. These data were fitted to heliospheric current sheet curves (Hoeksema 1989) extrapolated from the corona into the heliosphere in order to determine the best-fit coronal source-surface radius for each Carrington rotation. This work presents the kinematic analysis for two onsets of DEs (1985 December 13.5 and 1986 February 22.2). The DE onset time, when the comet supposedly crossed a magnetic sector boundary, is determined assuming that the disconnected plasma moves away from the nucleus at constant velocity (Voelzke & Matsuura 1998). This is compared with the analysis of (Yi et al. 1994b) which determined the time of disconnection assuming constantly accelerated linear motion. The velocity varies broadly from one DE to another. In this paper, we report the results of an analysis of four DEs observed from 13 through 14 December 1985 and on 22 February 1986. From a kinematic analysis of the widefield photographic images we calculated the disconnection time of the 1985 December 13-14 DEs to be December 13.5 and of the 1986 February 22 to be February 22.2, which are in good agreement with Yi et al. (1994b). The solar wind conditions around comet P/Halley, inferred by corotation of IMP-8 data to the comet, were such Send offprint requests to: M.R. Voelzke, e-mail: mvoelzke@astro.uni-bonn.de that comet P/Halley had just crossed the interplanetary magnetic field (IMF) sector boundary; the solar wind density was, respectively, 15 cm −3 and 7 cm −3 ; the solar wind speed was, respectively, 370 km s −1 and 500 km s −1 . We conclude that our results corroborate the idea that DEs are associated with sector boundary crossings and that the magnetic reconnection plays an important role in the formation of DEs and can be considered as the triggering mechanism (Niedner & Brandt 1978;Brandt et al. 1999).

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“…The onsets of DEs calculated in this work, an independent analysis of the observational data, are in good agreement with Brandt et al (1999).…”

Section: Analysis Of Individual Onsets Of Dessupporting

confidence: 82%

supporting

confidence: 88%

Section: Analysis Of Individual Onsets Of Desmentioning

confidence: 82%

Section: Analysis Of Individual Onsets Of Desmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The onsets of disconnection events of comet P/Halley on 1985 December 13-14 and 1986 February 22

Voelzke

Matsuura

2000

Astron. Astrophys. Suppl. Ser.

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Physics of Cometary Magnetospheres

Gombosi

2015

Magnetotails in the Solar System

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This tutorial summarizes our present, pre-Rosetta understanding of the basic physical processes operating in cometary environments with particular attention to cometary magnetotails. Ionization of cometary gases is responsible for most plasma processes in the magnetospheres of active comets. The interaction between the superalfvénic, magnetized solar wind and cometary ions forms a number of plasma boundaries starting with the weak bow shock and continuing with the contact surface (diamagnetic cavity boundary), the recombination layer and the inner shock. The plasma tail is sensitive to changes in the solar wind and to varying cometary activity. These processes will be explored in detail.

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Introduction

2014

Comets and Their Origin

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Disconnection Events (DEs) in Halley's Comet 1985–1986:

Cited by 25 publications

References 17 publications

The onsets of disconnection events of comet P/Halley on 1985 December 13-14 and 1986 February 22

The onsets of disconnection events of comet P/Halley on 1985 December 13-14 and 1986 February 22

Physics of Cometary Magnetospheres

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