The Distribution of Meteor Masses for Sporadic Meteors and Three Showers

Weiß, A.

doi:10.1071/ph610102

Cited by 14 publications

(5 citation statements)

References 2 publications

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“…We found s = 1.72 ± 0.01 by fitting the linear portion of diffusion-limited overdense duration data points with Figure 15 and using the relation N ∝ τ 3(1−s)/4 (Weiss 1961), where N is the cumulative number of echoes. The uncertainty here only depicts the uncertainty of least-squares fit.…”

Section: Mass Distributionmentioning

confidence: 99%

Radar observations of the 2011 October Draconid outburst

Ye¹,

Brown²,

Campbell-Brown³

et al. 2013

Monthly Notices of the Royal Astronomical Society

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A strong outburst of the October Draconid meteor shower was predicted for 2011 October 8. Here we present the observations obtained by the Canadian Meteor Orbit Radar (CMOR) during the 2011 outburst. CMOR recorded 61 multi-station Draconid echoes and 179 single-station overdense Draconid echoes (covering the magnitude range of +3 M V +7) between 16-20h UT on 2011 October 8. The mean radiant for the outburst was determined to be α g = 261.9 • ± 0.3 • , δ g = +55.3 • ± 0.3 • (J2000) from observations of the underdense multi-station echoes. This radiant location agrees with model predictions (e.g. to ∼ 1 • . The determined geocentric velocity was found to be ∼ 10 − 15% lower than the model value (17.0 − 19.1 km · s −1 versus 20.4 km · s −1 ), a discrepancy we attribute to undercorrection for atmospheric deceleration of low density Draconid meteoroids as well as to poor radar radiant geometry during the outburst peak. The mass index at the time of the outburst was determined to be ∼ 1.75 using the amplitude distribution of underdense echoes, in general agreement with the value of ∼ 1.72 found using the diffusion-limited durations of overdense Draconid echoes. The relative flux derived from overdense echo counts showed a similar variation to the meteor rate derived from visual observations. We were unable to measure the peak flux due to the high elevation of the radiant (and hence low elevation of specular Draconid echoes). Using the observed speed and electron line density measured by CMOR for all underdense Draconid echoes as a function of height as a constraint, we have applied the ablation model developed by Campbell-Brown & Koschny (2004). From these model comparisons, we find that Draconid meteoroids at radar sizes are consistent with a fixed grain number n grain = 100 and a variable grain mass m grain between 2 × 10 −8 kg and 5 × 10 −7 kg, with bulk and grain density of 300 kg · m −3 and 3 000 kg · m −3 , respectively. One particular Draconid underdense echo displayed well-defined Fresnel amplitude oscillations at four stations. The internal synchronization allowing us to measure absolute length as a function of time by combining the absolute timing offsets between stations. This event showed clear deceleration and modelling suggests that the number of grains for this meteoroid was of the order of 1 000 with grain masses between 10 −10 and 10 −9 kg, and a total mass of 2 × 10 −6 kg.

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Section: Mass Distributionmentioning

confidence: 99%

Radar observations of the 2011 October Draconid outburst

Ye¹,

Brown²,

Campbell-Brown³

et al. 2013

Monthly Notices of the Royal Astronomical Society

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“…However, the mass index of the η‐Aquarids may be used as these two showers are causally linked by a common meteoroid stream, that being associated with Halley's comet. The mass index for these meteors fainter than 10 14 electrons m −1 is 1.6 ( c = −0.6) [ Weiss , 1961]. In addition, the results of Weiss [1957], summarized by Elford [1967], show that the ratio of the flux of the Orionids to sporadic meteors above a zenithal line density of 10 14 electrons m −1 is 23/35.…”

Section: Interpretation Of Mf Meteor Backscattermentioning

confidence: 99%

“…Table 2 displays values of c o for various radar magnitudes, M R . These values were obtained from Weiss [1961] except for +3 < M R < +6 where we interpolate c o to be −0.5. Now, M R is related to q z by the following relation [ McKinley , 1961]: Converting M R to q z and using together with Table 2, and using Weiss 's [1957] flux results above 10 14 electrons m −1 as the starting point, we calculated K r in each q z regime.…”

Section: Interpretation Of Mf Meteor Backscattermentioning

confidence: 99%

“… a From Weiss [1961]. The assumption has been made that the mass index for the Orionids is identical to that of the η‐Aquarids due to their association with the same meteoroid stream (see text for details). …”

Section: Interpretation Of Mf Meteor Backscattermentioning

confidence: 99%

“…The former is most useful for high-speed showers as the sporadic rate drops at these speeds. The latter requires the use of a multistation radar system, a technique developed by Gill and Davies [1956] and Davies and Gill [1960] Weiss [1961]. The assumption has been made that the mass index for the Orionids is identical to that of the h-Aquarids due to their association with the same meteoroid stream (see text for details).…”

Section: Response To Meteor Showersmentioning

confidence: 99%

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Meteor radar response function: Application to the interpretation of meteor backscatter at medium frequency

2004

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[1] Recently, Cervera and Elford (2004) extended earlier work on the development of the meteor radar response function (Elford, 1964;Thomas et al., 1988) to include a nonuniform meteor ionization profile. This approach has the advantage that the height distribution of meteors expected to be observed by a radar meteor system is able to be accurately modeled and insights into the meteoroid chemistry to be gained. The meteor radar response function is also an important tool with regard to the interpretation of meteor backscatter in other areas, e.g., modeling the expected diurnal variation of sporadic meteors, investigating the expected echo distribution over the sky, and the calculation of the expected rate curves of meteor showers. We exemplify each of these techniques from the analysis of meteor data collected by the Buckland Park 2 MHz system during October 1997. In addition, we show that the response function may be used to quantify the echo rate of a given shower relative to the sporadic background and thus determine if that shower is able to be detected by the radar.

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4.4.5 Physical data

Hoffmeister¹

Astronomy and Astrophysics

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The Distribution of Meteor Masses for Sporadic Meteors and Three Showers

Cited by 14 publications

References 2 publications

Radar observations of the 2011 October Draconid outburst

Radar observations of the 2011 October Draconid outburst

Meteor radar response function: Application to the interpretation of meteor backscatter at medium frequency

4.4.5 Physical data

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