Radio Echo Measurements of the Orbits of Faint Sporadic Meteors

Davies, J. G.; Gill, J. S.

doi:10.1093/mnras/121.5.437

Cited by 38 publications

(26 citation statements)

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“…We are simply returning to the idea qualitatively outlined by Davies & Gill (1960) but equipped with modern observations and better computational speed. These authors hypothesized that the highinclination and low-eccentricity sporadic NT component ultimately originates from long-period comets.…”

Section: Previous Modelsmentioning

confidence: 99%

“…The north toroidal source was first discovered and fully described in the early 1960s from the analysis of Harvard Radio Meteor Project (Hawkins 1962(Hawkins , 1963, with hints coming from earlier projects such as at Jodrell Bank (e.g., Davies 1957;Davies & Gill 1960). Its counterpart, the south toroidal source was confirmed in a study of meteor orbit surveys by Jones & Brown (1993), and later in the more detailed study of AMOR data by Galligan & Baggaley (2005), or Jicamarca high-power large-aperture radar by Chau et al (2007).…”

Section: Introductionmentioning

confidence: 99%

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Dynamical Model for the Toroidal Sporadic Meteors

Pokorný

Vokrouhlický

Nesvorný

et al. 2014

ApJ

115

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More than a decade of radar operations by the Canadian Meteor Orbit Radar have allowed both young and moderately old streams to be distinguished from the dispersed sporadic background component. The latter has been categorized according to broad radiant regions visible to Earth-based observers into three broad classes: the helion and anti-helion source, the north and south apex sources, and the north and south toroidal sources (and a related arc structure). The first two are populated mainly by dust released from Jupiter-family comets and new comets. Proper modeling of the toroidal sources has not to date been accomplished. Here, we develop a steady-state model for the toroidal source of the sporadic meteoroid complex, compare our model with the available radar measurements, and investigate a contribution of dust particles from our model to the whole population of sporadic meteoroids. We find that the long-term stable part of the toroidal particles is mainly fed by dust released by Halley type (long period) comets (HTCs). Our synthetic model reproduces most of the observed features of the toroidal particles, including the most troublesome low-eccentricity component, which is due to a combination of two effects: particles' ability to decouple from Jupiter and circularize by the Poynting-Robertson effect, and large collision probability for orbits similar to that of the Earth. Our calibrated model also allows us to estimate the total mass of the HTC-released dust in space and check the flux necessary to maintain the cloud in a steady state.

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Section: Previous Modelsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dynamical Model for the Toroidal Sporadic Meteors

Pokorný

Vokrouhlický

Nesvorný

et al. 2014

ApJ

115

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“…Davies became interested in the problem of the existence or otherwise of hyperbolic meteors mentioned earlier and made extensive use of the Jodrell Bank telescopes in an attempt to solve this problem. Unfortunately, Davies was not one of the World's prolific publishers and, though having completed observations, eventually of 13000 sporadic meteors by 1955, these were not published until 1960 (Davies and Gill, 1960). The vast majority were found to be on elliptical orbits and the number of hyperbolic meteors were small enough to be attributable to observing errors.…”

Section: The Early Days Of Radio Astronomymentioning

confidence: 99%

The velocity of meteoroids: a historical review

Williams

2004

Atmos. Chem. Phys.

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“…For meteors brighter than M R~6 three groups lying on the ecliptic are recognized, one at the apex and two centered on points lying about 70° in longitude from the apex (Hawkins, 1956;Weiss and Smith, 1960;Davies and Gill, 1960). The last two groups, generally referred to as the sun and antisun groups, have diameters~60° to 70°.…”

Section: Shower Meteor Fluxesmentioning

confidence: 99%

“…The last two groups, generally referred to as the sun and antisun groups, have diameters~60° to 70°. At fainter magnitudes there is increased activity from regions lying about 60° north and south of the apex (Davies and Gill, 1960;Hawkins, 1962). For 10th-to 12th-mag meteors the average strength of this high-latitude activity is about 50 percent of the sun and antisun concentrations (Elford, Hawkins, and Southworth, 1964).…”

Section: Shower Meteor Fluxesmentioning

confidence: 99%

Meteor orbits and dust; the proceedings of a symposium

Hawkins¹

1967

Smithsonian Contributions to Astrophysics

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The Proceedings of the Symposium on Meteor Orbit* and Dust is published simultaneously as a NASA Special Publication (SP-135) and as Volume 11 of the Smithsonian Contributions to Astrophysics. This single publication thus serves in a dual capacity to satisfy the requirements of both agencies for the published record of this international meeting.The NASA Special Publications series, begun in 1962, makes available information derived from or of value to NASA activities, and includes such publications as conference proceedings, monographs, data compilations, handbooks, Bourcebooks, and special bibliographies.The IntroductionWe recently completed a general analysis of the atmospheric trajectories of 413 precisely reduced Super-Schmidt photographic meteors (Jacchia, Verniani, and Briggs, 1965). We studied the dependence of heights, lengths, decelerations, and magnitudes on such basic parameters as velocity, angle of incidence, and mass, as well as on derived parameters such as the ablation coefficient and the fragmentation index; the latter were in turn related to the other geometrical and physical characteristics, including the phenomena of wake and terminal blending. The results of the analysis are mainly concerned with physical characteristics of meteors; in this paper we shall limit ourselves to only a few points related to problems of orbits and distribution, namely, physical differences dependent on the type of orbit, peculiarities of individual showers, and the mass scale for photographic meteors.Systematic differences between groups of meteors Systematic differences in some physical characteristics between meteors in short-period and long-period orbits were first pointed out by Jacchia (1958Jacchia ( , 1963. He found that the beginning heights of meteors with aphelion distances greater than 7 a.u. were higher than the corresponding heights of meteors with aphelion distances smaller than 7 a.u. All meteors were, of course, reduced to the same brightness.• Smithsonian Astrophysical Observatory and Harvard College Observatory, Cambridge, Massachusetts.'Smithsonian Astrophysical Observatory and Harvard College Observatory; on leave from Centra Nationals per la Fisica dell'Atmosfera c la Meteorologia del C.N.R., Rome, Italy. * Smithsonian Astrophysical Observatory, Cambridge, Massachusetts.The present general analysis has confirmed the effect found by Jacchia: meteors with aphelion distance smaller than 6 a.u. appear 1.8 km lower than meteors in long-period orbits, reduced to the same velocity, mass, and zenith angle. The maximum light and end heights are correspondingly lower ( fig. 1). This effect is related to the different densities that we find for the two groups: on the average, meteors in short-period orbits appear to be about 1.4 times as dense as meteors in long-period orbits. In addition, for short-period meteors, the density increases as the aphelion distance decreases ( fig. 2). These systematic differences in density could be ascribed to the different conditions in which the meteoroids were formed ...

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Radio Echo Measurements of the Orbits of Faint Sporadic Meteors

Cited by 38 publications

References 0 publications

Dynamical Model for the Toroidal Sporadic Meteors

Dynamical Model for the Toroidal Sporadic Meteors

The velocity of meteoroids: a historical review

Meteor orbits and dust; the proceedings of a symposium

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