Robert Hawkes

Robert Hawkes
Mount Allison University · Department of Physics

PhD

About

96
Publications
7,440
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2,009
Citations
Citations since 2017
0 Research Items
497 Citations
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2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
Introduction
Interested in meteors and meteoroids, in particular ablation models, electro-optical observations, and meteoroid structure. Lab based laser ablation of meteorites. In science education interested in student research experiences, collaborative learning and technology in education.
Additional affiliations
July 1980 - June 2014
Mount Allison University
Position
  • Professor (Full)
July 1980 - June 2014
Mount Allison University
Position
  • Professor (Asst, Assoc. then Full)
Education
September 1974 - January 1979
The University of Western Ontario
Field of study
  • Physics (Astrophysics)

Publications

Publications (96)
Chapter
We have started a program called Go Global: Science Research at Mount Allison University. It provides high school students with the opportunity to work intensively as part of a research group for about 10 days. This analysis is based on a three-year operation of the program, starting in summer 2007. Our goal was to examine the issue of fostering st...
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The Canadian Automated Meteor Observatory (CAMO) detects occasional meteors with two maxima in the image intensified CCD based light curves. We report early results from an analysis of 21 of these events. Most of these events show qualitatively similar light curves, with a rounded luminous peak, followed by an almost linear sharp rise in the second...
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The optical trail widths of 30 faint meteors (average magnitude ∼+3, m ∼ 10−4 kg) were resolved and measured using the Canadian Automated Meteor Observatory (CAMO). CAMO is an automated, high-resolution intensified digital video system capable of detecting meteors as faint as magnitude +5. The observatory's two stations, separated by a baseline of...
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The optical width of 30 faint meteor trails was measured using the Canadian Automated Meteor Observatory. It was found that meteor widths varied as a function of the atmospheric mean free path, but were up to two orders larger in many cases.
Article
A British observational study of science classroom interactions was replicated in Atlantic Canada with 33 teacher-class units. Observational data from the Canadian classrooms were cluster-analysed and two preferred teaching styles emerged from this analysis. It was concluded that patterns of teaching in the Canadian classrooms studied differed subs...
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We have optically recorded faint meteors using a large aperture LLLTV (low light level television) system based on second generation image intensifiers. These data consist of 42 two-station meteors of which 13 were captured during an observing campaign near London, Ontario (Canada) in May 2004, and 29 during a campaign near Kiruna (Sweden) in Octob...
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New meteor showers should first be reported to the International Astronomical Union before they are discussed in the scientific literature (which includes WGN). The IAU keeps a tally of reported showers, and will officially name those showers that are established. The first batch of showers is up for official naming at the upcoming IAU General Asse...
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The Canadian Automated Meteor Observatory (CAMO) has been constructed to automatically observe meteors using image-intensified CCD systems to better understand the meteor ablation process, and to measure the daily meteoroid flux as well as mass and velocity distributions. The system features both high spatial and temporal resolution, and can track...
Article
Laboratory based laser ablation techniques can be used to study the size of the luminous region, predict spectral features, estimate the luminous efficiency factor, and assess the role of chemically differentiated thermal ablation. A pulsed Nd:YAG laser was used to ablate regions from ordinary and carbonaceous chondrite meteorites. CCD cameras and...
Article
Light production mechanisms during ablation of meteors in planetary atmospheres are still not well understood. We have used a high-power pulsed (15 mJ per 10-ns pulse) Nd:YAG laser, frequency-doubled to 532-nm wavelength, to heat chondritic meteorite samples rapidly, and then used CCD imaging and spectral cameras to search for light produced by the...
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A digital image intensified CCD camera with an electronically gated image intensifier was used to produce very short duration images of meteors. The observational system employed a 0.40 m F/4.5 Newtonian telescope to obtain high spatial resolution. A second intensified CCD camera was used to yield height information using parallax. At a typical met...
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We report results from two station, short-baseline (<100 m) high resolution measurements of faint meteors (limiting meteor magnitude +9) with the goal of measuring their optical trail widths. Meteors were observed using two 0.40 m Newtonian telescopes (field of view ∼0.4 degrees) equipped with image intensifiers. Both telescopes were vertically ori...
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Interstellar origin meteoroids have now been detected using radar, image intensified video, large aperture radar and space dust impact techniques. Dynamical and radiation production mechanisms will eject some meteoroids from other planetary systems into orbits which will impact Earth with high geocentric velocities. In this paper we numerically mod...
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Conventional meteoroid theory assumes that the dominant mode of ablation (which we will refer to as thermal ablation) is by evaporation following intense heating during atmospheric flight. Light production results from excitation of ablated meteoroid atoms following collisions with atmospheric constituents. In this paper, we consider the question o...
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In this paper we review the literature regarding collabora-tive modes of physics teaching and report in some detail on the studio physics mode of instruction at Acadia University and the experiential physics teaching method at Mount Allison University.
Chapter
Meteor radar observations of ionized trails in the Earth’s atmosphere provide observations that do not depend on weather conditions and time of day and provide good statistics for analysis. Further development in the new quasitomographic analysis of the goniometric data of the Kazan meteoric radar has revealed a number of very weak meteoric streams...
Chapter
The successful application of modern observing techniques for Leonid storm observations show that meteor (shower) detections will have a bright future if the field will pursue difficult but important questions. How to forecast a satellite threatening meteor storm? What happens to the organic matter in meteors and can this be an important source of...
Chapter
We used light curve analysis to search for evidence of the dustball meteoroid model. Leonid, Taurid, Alpha Monocerotid and sporadic meteors from November 2003 were observed and analyzed using uniform methodology. Meteors from these four sources were examined for evidence of fragmentation by examining light curve shape and searching for light curve...
Chapter
We examine the potential contamination of cometary nuclei through impacts from asteroidal origin meteoroids. The paper uses a simple model and has the goal of determining whether asteroidal contamination is potentially significant. We assume a meteoroid power law mass distribution with index values in the range from s=1.83 to s=2.09. We used maximu...
Chapter
In this study we numerically modelled the atmospheric ablation and luminosity of cometary structure meteoroids with geocentric velocities from 71 to 200 km/s. We considered meteoroid masses ranging from 10−13 to 10−6 kg. Expected heights of ablation and maximum luminosity absolute magnitudes are determined. Height and trail length values are used t...
Article
In this study we numerically modelled the atmospheric ablation and luminosity of cometary structure meteoroids with geocentric velocities from 71 to 200km/s. We considered meteoroid masses ranging from 10−13 to 10−6kg. Expected heights of ablation and maximum luminosity absolute magnitudes are determined. Height and trail length values are used to...
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Conventional ablation theory assumes that a meteoroid undergoes intensive heating during atmospheric flight and surface atoms are liberated through thermal processes. Our research has indicated that physical sputtering could play a significant role in meteoroid mass loss. Using a 4th order Runge-Kutta numerical integration technique, we tabulated t...
Article
We used light curve analysis to search for evidence of the dustball meteoroid model. Leonid, Taurid, Alpha Monocerotid and sporadic meteors from November 2003 were observed and analyzed using uniform methodology. Meteors from these four sources were examined for evidence of fragmentation by examining light curve shape and searching for light curve...
Article
We examine the potential contamination of cometary nuclei through impacts from asteroidal origin meteoroids. The paper uses a simple model and has the goal of determining whether asteroidal contamination is potentially significant. We assume a meteoroid power law mass distribution with index values in the range from s=1.83 to s=2.09. We used maximu...
Article
The mean bulk density of small meteoroids remains a poorly measured quantity. Based on photographic observations of large (gram-sized) meteoroids and the theory of quasi-continuous fragmentation Lebedinets (1987) and Babadzhanov (1994) estimated the average bulk density of meteoroids to be near 3300kg m-3, with values for individual meteoroids rang...
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Image intensifiers coupled to video frame rate CCDs have the capability of observing much shorter duration events than conventional multi-channel optical astronomy detection techniques. This equipment is particularly suited to observations of unpredicted stellar occultations. An image intensified CCD system can offer a moderately sensitive multi-ch...
Article
The most widely accepted model for the structure of cometary meteoroids is a dustaball with grains bound together by a more volatile substance [1]. In this paper we estimate the size distribution of dustball grains from meteor flare duration, using image intensified CCD or 1998 Leonid meteors. Upon the assumption of simultaneous release of dustball...
Article
Video and radar observations of the 2000 Leonid shower are presented. We find strong evidence that the first peak in the shower on 2000 November 17 near 8 ut resulting from 1932 ejecta is much stronger than previously recognized and larger than the broader peak on November 18 resulting from 1866 and 1733 ejecta. In particular, we find a TV–radar av...
Article
We report here evidence for significant transverse spread of the light production region in bright Leonid meteors. One Leonid meteor has an apparent spread in the light production region of about 600 m perpendicular to the flight path for the meteor, that transverse spread persisting for at least 0.3 s. We have also detected short-duration, jet-lik...
Article
Single-and double-station video observations of the 1999 Leonid shower made from Israel are presented. A total of 232 double-station Leonids had trajectories computed. Additionally, some 2500 single-station Leonids were used to measure the Leonid storm ux and mass distribution in the interval from 0.5 –3 UT 18 November 1999. The height distribution...
Article
Abstract— We have used a 3.0 m diameter liquid mirror telescope (LMT) coupled to a microchannel plate image-intensified charge-coupled device (CCD) detector to study the 1999 Leonid meteor shower. This is the largest aperture optical instrument ever utilized for meteor detection. While the observing system is sensitive down to stars of +18 astronom...
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The dustball model of meteoroid structure would be expected to lead to short duration fluctuations on light curves, anomalous decelerations, and instantaneous light production over a significant spatial region. Detection of these features with conventional image intensified CCD approaches has proved elusive. We provide an overview of six improvemen...
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Full-text available
We present ground-based observations of the 1999 and 2000 Leonid showers. The 1999 shower was observed with image intensified video cameras at various sites around the world. Two station data were obtained in Israel, and heights were obtained for 233 double-station Leonids. The peak flux was also found from Israel data; both show an early peak much...
Article
Abstract— Two-station electro-optical observations of the 1998 Leonid shower are presented. Precise heights and light curves were obtained for 79 Leonid meteors that ranged in brightness (at maximum luminosity) from +0.3 to +6.1 astronomical magnitude. The mean photometric mass of the data sample was 1.4 × 10−6 kg. The dependence of astronomical ma...
Article
Analysis of light curves of faint meteors seem to suggest that most meteoroids are collections of hundreds to thousands of fundamental grains at least some of which are released prior to the onset of intensive ablation. We would expect these grains, unless extremely uniform in physical properties, to be aerodynamically separated during flight, and...
Article
The IAU Meteor Data Centre (MDC), maintained at Lund, Sweden, under the direction of Bertil Lindblad, remains a valuable resource for the meteor community. Commission 22 currently has representatives on two inter-commission Working Groups, The Prevention of Interplanetary Pollution (Chair C. S. L. Keay of Commission 22) and Near-Earth Objects (IAU...
Article
Abstract— We have used dual coaxial microchannel plate image-intensified monochrome charge-coupled device (CCD) detectors run at standard NTSC frame rates (30 frames per second, fps) to study the Leonid meteor shower on 1998 November 17 from an airborne platform at an altitude of ∼13 km. These observations were part of NASA's 1998 Leonid multi-inst...
Article
Meteoroids can be observed at collision with the Earth's atmosphere as meteors. Different methods of observing meteors are presented: besides the traditional counts of individual events, exact methods yield also data on the geometry of the atmospheric trajectory; on the dynamics and ablation of the body in the atmosphere; on radiation; on the spect...
Article
A total of 18 image intensified CCD detectors were deployed at 6 locations (two in Negev Desert, Israel, and one in each of the Canary Islands, Long Key in Florida, Haleakala in Hawaii, and the Kwajalein Atoll) to provide a real-time reporting system, as well as data for subsequent detailed analysis, for the 1999 Leonid shower. Fields of view range...
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Photometric low-light level video observations of 1999 Leonid storm meteors have been obtained from two airborne platforms during the Leonid multi-instrument aircraft campaign (Leonid MAC). The 1999 Leonid light curves tend to be skewed towards the end point of the trajectory, while the 1998 Leonid light curves were not. The variation in the light...
Article
Video techniques, which provide high sensitivity, portability, moderate spatial resolution and excellent temporal resolution promise to be one of the most valuable methods for study of the forthcoming Leonid storm(s). While an unintensified video camera will detect very bright meteors (typically about 0 magnitude), some sort of image intensifier is...
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We announce the first two detections from an optical search for meteoroids from interstellar space. These meteoroids were detected June 25 1995 02:21:43 UT and June 27 1995 02:48:32. They are 4 and 8 standard deviations above the eccentricity limit for hyperbolic orbits. These meteoroids have pre-atmospheric masses of the order of 10-7 kg. We extra...
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We review observational evidence that suggests that a small percentage (<2%) of incoming meteors are in hyperbolic orbits, and that the percentage increases with decreasing mass. Considering random stellar motions in the solar neighbourhood, interstellar meteors would be expected to arrive at earth with geocentric velocities ranging from about 21 t...
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Video meteor observations have been performed by amateur astronomers for more than 10 years. They enjoy a rapidly increasing interest in the meteor community and will evolve into a powerful tool for amateur observers in the near future. Video meteor observation is the key to a fundamental increase of our knowledge about meteoroid populations and th...
Chapter
As has been the usual practice for a number of years in Commission 22, members of the commission with expertise in different areas have prepared contributions reviewing their own fields and these have been consolidated by the President and Secretary to form the report as it appears below. Over the past triennium there have been a number of conferen...
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Large Near-Earth-Asteroids have played a role in modifying the character of the surface geology of the Earth over long time scales through impacts. Recent modeling of the disruption of large meteoroids during atmospheric flight has emphasized the dramatic effects that smaller objects may also have on the Earth's surface. However, comparison of thes...
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Wake is the degree to which an iJlsta~ztaneous meteor image is spatially distributed. We used a MCP intens~fied SIT video detector preceded by a mechatffcal rotating shutter to search f~»" wake in a sample of faint (down to +7.8 apparent magnitude), mainly sporadic meteors. The detailed analysis of 217 video frames (25 meteors) yielded only oJte me...
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Image intensified video detection systems were used to observe the 1991 Perseid meteor shower from two locations in eastern Canada. In 29.6 hours of total observing time a total of 668 meteors were detected, of which 403 were Perseids. We derived a profile of TVZHR (television zenithal hourly rate) values for the 1991 Perseid shower over the solar...
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On October 9, 1992, a fireball, brighter than the full Moon, appeared over West Virginia, traveled some 700 km in a northeasterly direction, and culminated in at least one meteorite impact. A 12.4-kg ordinary chondrite (H6 monomict breccia) was recovered in Peekskill, New York. Fortuitously, the event was captured on several video recordings. Peeks...
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ON 9 October 1992, a bright fireball appeared over West Virginia, travelled some 700 km in a northeasterly direction, and culminated in at least one impact: a 12.4-kg ordinary chondrite was recovered in Peekskill, New York1. Fortuitously, the event was captured on several video recordings, which provide a detailed record of both the fragmentation o...
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A cluster of 5 near-simultaneous, parallel meteors was detected with an image-intensified video system on October 18, 1985. The detailed analysis of the video frames suggests that each of the 5 main objects was in turn composed of at least 4 smaller meteoroids.
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This paper describes techniques for trajectory, light curve and orbital analysis of image intensified television meteors recorded at two stations. It will be argued that simple partial screen reference star fitting is preferable to higher order whole screen fits, and that only modest improvements in accuracy result from additional reference stars....
Article
The two component dustball model was used in numerical lag computation. Detached grain lag is typically less than 2 km, with expected wakes of a few hundred meters. True wake in television meteors is masked by apparent wake due to the combined effects of image persistence and blooming. To partially circumvent this problem, we modified a dual MCP in...
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Coordination and standardization of video-based meteor observations is needed. Suggested reporting forms and procedures are outlined in this article.
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The key elements of a video-based meteor observing system are discussed. A recommended system, consisting of a 50 mm focal length objective lens, a 25 mm microchannel plate (MCP) image intensifier lens coupled to a sensitive monochrome CCD video camera is described.
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The age of the Orionid meteoroid stream is estimated from the ratio of the mass of the stream to that of Halley's comet. A number of measurements spanning a range of about 5 visual magnitudes of the flux of meteoroids from radar, low-light-level TV and visual observations of the Orionid meteor shower have been used to determine the cumulative zenit...
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Absolute magnitudes, photometric masses, trajectory data, and light curves have been obtained for a sample of 17 meteors from the 1984 Orionid shower. The meteors have an absolute television magnitude of +4.8 mag and a mean vertical trail length of 6.9 km. The results indicate that there is significant variation in either physical structure or chem...
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An effective method for identifying shower meteors and determining atmospheric trajectories from single station observations has been developed and tested with computer-simulated and low light level television meteor data. The apparent velocity and calculated height information are used to reduce significantly the number of test radiants in the sho...
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Previous studies of the residual masses resulting from ablation of small meteoroid grains have been concerned with the ablation of particles which enter the atmosphere independently. There is widespread evidence that fragmentation is a common occurrence for meteors ranging from bright fireballs to the smallest meteors recorded with optical techniqu...
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Features of several types of image intensifier and video systems for studying meteors are described. Emphasis is placed on data analysis and sky-scanning procedures which will be implemented to optimize the use of solid-state imaging systems, which are linked through fiber optics to signal analysis circuitry. It is shown that current meteor data ar...
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We have extended the theory of Fox, Williams & Hughes for the evolution of the Geminid meteor stream under the perturbing influence of the gravitation attraction of the planets. Whereas the original theory allowed for the planetary perturbations by ascribing to each particle the rates of change of orbital elements appropriate to the mean orbit we n...
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Numerical solutions of the equations of meteor ablation in the Earth's atmosphere have been obtained using a variable step size Runge-Kutta technique in order to determine the size of the residual mass resulting from atmospheric flight. The equations used include effects of meteoroid heat capacity and thermal radiation, and a realistic atmospheric...
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The atmospheric trajectories, velocities, brightnesses and orbits of double-station TV-meteors, 3 magnitudes fainter than those photographed by Super-Schmidt cameras are given. The beginning heights of A and C meteors found in photographic observations are compared with the TV-meteor data. The strongest component of the TV-meteors forms a natural c...
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Results for the first two station television intensifier studies of faint meteors are examined. The first system was a three stage image intensifier fiber-optically coupled to a vidicon television camera with a 50 mm f/1.4. The second system consisted of a two-stage image intensifier coupled to a vidicon tube, with a limiting sensitivity of about +...
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Single station studies cannot provide detailed information such as zenith angle, velocity, heights and magnitude for individual meteors and Ceplecha (1976) has stressed the need for two station television observations which could provide such information through triangulation analyses. This paper deals with some of the results of the first two stat...
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We propose that the observed variation of the initial radius of meteor trains with height is largely the result of the rapid rotation (∼ 5 × 10³ rad/s) of the meteoroids which causes considerable spreading of the meteoroid grains in the interval between grain release and the onset of intensive vaporization. This is shown to be consistent with the e...
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A quantitative model for the ablation of dustball meteors is presented. The model assumes meteoric bodies are composed of grains held together by a lower boiling point 'glue'. Once the boiling point of the 'glue' is reached grains are detached. Light is assumed to be produced only by detached grains. For meteors fainter than about +5 magnitude, the...
Article
The condensation‐accretion (warm rain) and Wegener‐Bergeron (ice crystal) theories of rain formation are briefly outlined. In a number of situations the former process must be applicable. However, conventional models of the warm rain process lead to a 15–25 μm radius barrier to drop growth in observed cloud lifetimes. Modifications to the process t...
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Observations of very faint meteors provide a test of the theories of meteoroid structure. With a recently developed low-light-level television system, such observations have been made, and it has been found that the solid compact meteoroid model must be abandoned. Our observations, which are in good agreement with the radio results of Verniani, giv...
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The meteoric influx explanation of superrotation (Mitra, 1974) is re-examined. It is shown that the excess orbital angular momentum of the meteoroids is transferred to the region below about 110 km, and thus can probably not account for the superrotation of the 150–400 km atmospheric layer.
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A low light level television meteor observing system sensitive to stars of magnitude +8.5 is briefly described. Correction procedures for a nonuniform field of view and the movement of the meteor image are developed. Observations of sporadic meteors with the system yielded a mass distribution index of 2.02 plus or minus 0.04 valid over the absolute...
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THE variation of brightness as a function of height when a meteoroid burns up (ablates) in the Earth's atmosphere is governed by the physical properties of the meteoroid. The basic theory of the ablation of a solid meteoroid to due to Öpik1, and the theoretical light curves are in fairly good agreement with the observed light-curves of very bright...

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