Properties of dust in comet P/Halley measured by the Vega-2 three-channel spectrometer

Krasnopolsky, V. A.; Мороз, В. І.; Krysko, A. A.; Tkachuk, A. Yu.; Moreels, G.; Clairemidi, J.; Parisot, J. P.; Gogoshev, M. M.; Gogosheva, Ts.

doi:10.1007/978-3-642-82971-0_125

Cited by 19 publications

(15 citation statements)

References 9 publications

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“…According to Jessberger & Kissel (1991), oxygen in the ice of comet Halley is equal to 0.56 of the total oxygen in the comet. Comparing the gas and dust rates in comet Hyakutake (Q gas \ 2 ] 1029 s~1 and Afo \ 72 m ; Mumma et al 1996 ;Hicks & Fink 1996 ;Millis et al 1996) with those in comet Halley during the V ega 2 Ñyby s~1 ; Krasnopolsky et al 1988 ;(Q gas \ 1030 and Afo \ 170 m ;AÏHearn et al 1995 ;Krasnopolsky 1997) and assuming a similar composition of dust in both comets, we Ðnd that oxygen in ice constitutes 0.27 of the total oxygen in comet Hyakutake. In this calculation Afo is a measurable quantity that is proportional to the dust production rate in comets (AÏHearn et al 1995) : A is the particle albedo, and f is the Ðlling factor for dust particles within an aperture o.…”

Section: Other Emissionsmentioning

confidence: 96%

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Spectroscopy of Comet Hyakutake at 80–700 A: First Detection of Solar Wind Charge Transfer Emissions

Krasnopolsky

Mumma

2001

ApJ

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Spectra of comet Hyakutake at 80È700 observed with a resolving power of 10 reveal for the Ðrst A time the emission lines of multiple-charged ions that are brought to the comet by the solar wind and excited in charge exchange with cometary neutral species. The most prominent lines are O4`j215, C4j 249, and He`j304. Some other lines, which are of comparable strength, are blended. The results convincingly prove that the charge exchange mechanism is the dominant process in excitation of X-ray and EUV emissions from comets. The He`line at 304 is emitted in a similar process by the solar wind A a-particles. The quantum yield of charge exchange is B4 photons per heavy ion in collisionally thick parts of comae, and the photon luminosity of charge exchange at energy below 100 eV exceeds that above 100 eV by a factor of 2. However, the energetic luminosity below 100 eV is smaller than that above 100 eV by a factor of 2. The O`lines at 538/539, 617, and 430/442 are formed by photoioniza-A tion of atomic oxygen similarly to those in EarthÏs dayglow. The observed depletion of neon relative to the solar abundance by more than a factor of 2600 conÐrms the current view that Oort cloud comets formed in the Jupiter-Neptune region of the solar nebula.

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Section: Other Emissionsmentioning

confidence: 96%

“…5 (Krasnopolsky et al 1988). We obtained the O scale length of 2 ] 106 km for photoionization and charge exchange with the solar wind protons.…”

Section: Other Emissionsmentioning

confidence: 99%

Spectroscopy of Comet Hyakutake at 80–700 A: First Detection of Solar Wind Charge Transfer Emissions

Krasnopolsky

Mumma

2001

ApJ

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“…Several dust production rates were estimated during the Giotto and Vega 1-2 flybys of the nucleus (e.g., Edenhofer et al 1987;Hanner et al 1987;Mazets et al 1987;Krasnopolsky et al 1987). However, these estimates are strongly dependent on the spacecraft's distance from the nucleus and do not necessarily reflect long-term variations in the cometary activity.…”

Section: Afρmentioning

confidence: 99%

Modeling the past and future activity of the Halleyid meteor showers

Egal

Wiegert

Brown

et al. 2020

A&A

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Context. We present a new numerical model of the η-Aquariid and Orionid meteor showers. Aims. The model investigates the origin, variability, and age of the η-Aquariid and Orionid apparitions from 1985 to the present day in order to forecast their activity over the next several decades. Methods. Through the numerical integration of millions of simulated meteoroids and a custom-made particle weighting scheme, we model the characteristics of every η-Aquariid and Orionid apparition between 1985 and 2050. The modeled showers are calibrated using 35 yr of meteor observations, including the shower activity profiles and interannual variability. Results. Our model reproduces the general characteristics of the present-day η-Aquariids and part of the Orionid activity. Simulations suggest that the age of the η-Aquariids somewhat exceeds 5000 yr, while a greater fraction of the Orionids is composed of older material. The 1:6 mean motion resonance with Jupiter plays a major role in generating some (but not all) Halleyid stream outbursts. We find consistent evidence for a periodicity of 11.8 yr in both the observations and modeled maximum meteor rates for the Orionids. Weaker evidence of a 10.7 yr period in the peak activity for the η-Aquariids needs to be investigated with future meteor observations. The extension of our model to future years predicts no significant Orionid outbursts through 2050 and four significant η-Aquariid outbursts, in 2023, 2024, 2045, and 2046.

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“…Further density estimates are provided by studies of the particulate material, especially in Halley's comet. Krasnopolsky et al (1987) evaluated the density of dust particles in this object from comparison of the dust-impact measurements with the data obtained with a three-channel spectrometer on VEGA-2, finding a value of ~0.3 g/cm 3 with an uncertainty of about a factor of 2. Crifo (1988) arrived at a density of 0.3 g/cm 3 or less for Halley's dust grains from his fitting the observed thermal infrared emission features in the 10-20 /im region.…”

Section: Erosion Rates Of the Active Regionsmentioning

confidence: 99%

Cometary Activity, Discrete Outgassing Areas, and Dust-Jet Formation

Sekanina

1991

International Astronomical Union Colloquium

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Abstract.Major progress has recently been achieved in the understanding of the coma morphology of dust comets. The conceptual models for the various types of feature observed in the coma (jets, spirals, halos, fans, etc.), their computer simulation, and the hydrodynamic models for jet formation are critically reviewed, and evidence for anisotropic, strongly collimated flows of ejecta emanating from discrete active regions (vents) on the rotating cometary nuclei is presented. The techniques employed to generate synthetic comet images that simulate the observed features are described and their relevance to the primary objectives of coma-morphology studies is exemplified. Modelling of temporal variations in the water emission from discrete active regions suggests that production curves asymmetric with respect to perihelion should be commonplace. Critical comparisons are offered with the activity profiles of Encke’s comet and with light curves of disappearing comets and comets that undergo outbursts. Discussed next is the potential evolutionary significance of nuclear shape, the fractional area of the surface that is active, the vents’ erosion rate, and available information on their activation, aging, dormancy, migration, rejuvenation, and extinction. Recent developments in the understanding of the processes that cause the nongravitational perturbations of cometary motions are reviewed and the observed discontinuities are identified with birth of new sources and/or deactivation of old vents.

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Properties of dust in comet P/Halley measured by the Vega-2 three-channel spectrometer

Cited by 19 publications

References 9 publications

Spectroscopy of Comet Hyakutake at 80–700 A: First Detection of Solar Wind Charge Transfer Emissions

Spectroscopy of Comet Hyakutake at 80–700 A: First Detection of Solar Wind Charge Transfer Emissions

Modeling the past and future activity of the Halleyid meteor showers

Cometary Activity, Discrete Outgassing Areas, and Dust-Jet Formation

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