Physics of Meteoric Phenomena

Бронштен, В. А.

doi:10.1007/978-94-009-7222-3

Cited by 397 publications

(439 citation statements)

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“…The echo-forming mechanism suggested by Westman (1997) depends on a combination of increased ionisation rate and compression of the interaction volume in front of a meteoroid to raise the electron density to above critical. For this mechanism to work, the meteor-gas interaction must take place in the so-called free molecular¯ow regime (Bronshten, 1983). If the particle size is increased at a given atmospheric mean free path, the interaction moves away from the free-molecular regime into a transitional regime where a part of the ablated meteor matter is continually slipping o the meteor coma and into the meteor trail.…”

Section: Discussionmentioning

confidence: 99%

“…If the particle size is increased at a given atmospheric mean free path, the interaction moves away from the free-molecular regime into a transitional regime where a part of the ablated meteor matter is continually slipping o the meteor coma and into the meteor trail. As de®ned by Bronshten (1983), a 1-mm radius particle would remain in the free-molecular regime down to about 85-km altitude. Of course, the boundaries between the di erent¯ow regimes are not hard, and it appears that some aspect of the target formation is very sensitive to plasma loss, thus possibly preventing the plasma density from ever reaching critical in the case of the larger particles.…”

Section: Discussionmentioning

confidence: 99%

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Meteor fluxes and visual magnitudes from EISCAT radar event rates: a comparison with cross-section based magnitude estimates and optical data

et al. 1998

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Abstract. Incoherent scatter radars (ISR) are versatile instruments for continuous monitoring of ionisation processes in the Earth's atmosphere. EISCAT, The European Incoherent Scatter facility has proven e ective also in meteor studies. The time resolution of the radar can be reduced to a few milliseconds, su cient to resolve the passage of individual meteors through the narrow ISR beam. Methods for group and phase velocity determination of the meteoroids and the discrepancy between the results related to the target behaviour are presented. The radar cross sections of echoes associated with moving meteoroids (``meteor head echoes'') are very small and increase with decreasing wavelength. The parent meteoroids are found to have visual magnitudes far below the detection limit of most optical observations. The equivalent visual magnitude limit of the smallest objects observed by EISCAT in the current experiments has been estimated by two di erent methods, both from the cross-section measurements and from the measured event rates. Both methods give a limit value of +10 for the smallest objects while the upper limit is +4. The lower limit of the visual magnitude for the collocated optical measurement system is +4. Thus the two detection systems observe two di erent meteor size ranges, with the radar almost reaching micrometeorite population. Meteor¯uxes estimated from the event rates and the radar system parameters agree well with previous extrapolated values for this size range.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Meteor fluxes and visual magnitudes from EISCAT radar event rates: a comparison with cross-section based magnitude estimates and optical data

et al. 1998

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“…The ablation in our model starts as soon as the surface of the meteoroid reaches the boiling temperature (e.g. Bronshten 1983), which means as the classical model of ablation suggests, when the "glue" evaporates and grains are released. The classical equation of mass loss is then given by:…”

Section: Ablation Modelmentioning

confidence: 97%

“…where Λ, the heat-transfer coefficient, is equal to or less than unity, since the energy expended on ablation cannot exceed the total kinetic energy of the oncoming stream molecules (Bronshten 1983), and L is the heat of ablation (energy that must be delivered to a mass dm in order to melt and/or vaporize it).…”

Section: Ablation Modelmentioning

confidence: 99%

Bulk density of small meteoroids

Kikwaya

Campbell-Brown

Brown

2011

A&A

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Aims. Here we report on precise metric and photometric observations of 107 optical meteors, which were simultaneously recorded at multiple stations using three different intensified video camera systems. The purpose is to estimate bulk meteoroid density, link small meteoroids to their parent bodies based on dynamical and physical density values expected for different small body populations, to better understand and explain the dynamical evolution of meteoroids after release from their parent bodies. Methods. The video systems used had image sizes ranging from 640 × 480 to 1360 × 1036 pixels, with pixel scales from 0.01 • per pixel to 0.05 • per pixel, and limiting meteor magnitudes ranging from M v = +2.5 to +6.0. We find that 78% of our sample show noticeable deceleration, allowing more robust constraints to be placed on density estimates. The density of each meteoroid is estimated by simultaneously fitting the observed deceleration and lightcurve using a model based on thermal fragmentation, conservation of energy and momentum. The entire phase space of the model free parameters is explored for each event to find ranges of parameters which fit the observations within the measurement uncertainty. Results. (a) We have analysed our data by first associating each of our events with one of the five meteoroid classes. The average density of meteoroids whose orbits are asteroidal and chondritic (AC) is 4200 kg m −3 suggesting an asteroidal parentage, possibly related to the high-iron content population. Meteoroids with orbits belonging to Jupiter family comets (JFCs) have an average density of 3100 ± 300 kg m −3 . This high density is found for all meteoroids with JFC-like orbits and supports the notion that the refractory material reported from the Stardust measurements of 81P/Wild 2 dust is common among the broader JFC population. This high density is also the average bulk density for the 4 meteoroids with orbits belonging to the Ecliptic shower-type class (ES) also related to JFCs. Both categories we suggest are chondritic based on their high bulk density. Meteoroids of HT (Halley type) orbits have a minimum bulk density value of 360 +400 −100 kg m −3 and a maximum value of 1510 +400 −900 kg m −3 . This is consistent with many previous works which suggest bulk cometary meteoroid density is low. SA (Sun-approaching)-type meteoroids show a density spread from 1000 kg m −3 to 4000 kg m −3 , reflecting multiple origins. (b) We found two different meteor showers in our sample: Perseids (10 meteoroids, ∼11% of our sample) with an average bulk density of 620 kg m −3 and Northern Iota Aquariids (4 meteoroids) with an average bulk density of 3200 kg m −3 , consistent with the notion that the NIA derive from 2P/Encke.

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“…The velocity v(t) and mass m (t) of a projectile are represented by the following equations, using the theory of dynamics of a meteoroid by Bronshten [1983]: 4. A simplified model can predict penetration track lengths and diameters of captured projectiles.…”

Section: Data Scatter and Track Shapementioning

confidence: 99%

Hypervelocity impact experiments on aerogel dust collector

Kitazawa¹,

Fujiwara²,

Kadono³

et al. 1999

J. Geophys. Res.

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Abstract. Laboratory hypervelocity impact experiments were conducted to verify the performance of aerogel dust collectors used for gathering meteorolds and space debris in the near-Earth environment and to derive the relationships of various parameters characterizing the projectile with morphology of tracks left by t•he penetrating projectile in the aerogel collector pad. Silica aerogel collectors of 0.03 g/cm -• density were impacted at velocities ranging from 1 to 14 km/s with projectiles of aluminum oxide, olivine, or sodalime glass, with diameters ranging from 10 to 400/xm. At impact velocities below 6 km/s the projectiles were captured without fragmentation by the aerogel collector and, in many instances, without complete ablation even at 12 km/s. The shapes and dimensions of the penetration tracks left in the aerogel collector were correlated with the impact parameters, and the results permitted derivation of a series of equations relating the track dimensions to incoming projectile size, impact energy, and other projectile parameters. A simplified model, similar to meteor-entry phenomena, was used to predict the trends in experimental penetration track lengths and the diameters of captured projectiles. IntroductionSolid particles present in the near-Earth environment derive from either natural or artificial origin and are termed "meteoroids" and "space debris", respectively. Meteoroids are considered to be supplied from comets, asteroids, and planets, and some known as interstellar dust particles or interstellar grains are from outside the solar system [Griin et al., 1993]. Since meteoroids are thought to be closely related with the evolution of the solar system, study of these materials provides us with crucial information on the source materials for the solar system. In situ sampling of meteoroids in space can avoid contamination by terrestrial sources, which is unavoidable in sampling on Earth.Space debris is the product of normal satellite operations, the deterioration of satellites, and the fragmentation or breakup of satellites [Johnson and McKnight, 1991]. It is important to investigate micrometer-to-millimeter-sized debris, the range within which the majority of debris particles lie, because this changes the characteristics of the materials of spacecraft or of the on-board parts after colliding with them. The distribution and composition of small-sized debris are not well known, as these particles are too small to be observed with ground-based telescopes or radars. In situ sampling of dust particles is useful for getting material information on the de- The authors developed a dust collector made from silica aerogel to take the Manipulator Flight Demonstration (MFD) flight opportunity aboard the Space Shuttle (STS-85),

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Physics of Meteoric Phenomena

Abstract: R. LUST, President Max-Planck Gesellscha/t/iir Forderung der Wissenscha/ten, Miinchen, F.R.G. R~E.. ¥ul)IN, Vn4ve~fP)l pI tot;onto, T~~l!nto, Ont., Canada

Cited by 397 publications

References 4 publications

Meteor fluxes and visual magnitudes from EISCAT radar event rates: a comparison with cross-section based magnitude estimates and optical data

Meteor fluxes and visual magnitudes from EISCAT radar event rates: a comparison with cross-section based magnitude estimates and optical data

Bulk density of small meteoroids

Hypervelocity impact experiments on aerogel dust collector

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