On meteor ablation in the atmosphere

Verniani, Franco

doi:10.1007/bf02733242

Cited by 10 publications

(8 citation statements)

References 20 publications

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“…It follows that ( where p=,x is the atmosphere density at the height of maximum ablation rate. We shall not continue the development of the various other possible equations, as they may all be found in the paper by Verniani [1961]. Equations 5 and 6 are only approximateJy correct.…”

Section: Theorymentioning

confidence: 97%

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Radar observations of meteor deceleration

Evans¹

1966

J. Geophys. Res.

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By using a narrow‐beam high‐power radar operating at 68 cm it has been possible to detect meteors traveling radially toward the radar. In these observations the antenna is directed at the radiant point of an intense meteor shower, and the receiver is tuned to the expected Doppler‐shifted signal. Because the actual Doppler shift can be measured with precision, both the velocity and the deceleration of the approaching meteor can be determined. The behavior of the velocity is compared with the theory for a solid particle entering the earth's atmosphere at heights where no air cap is formed. Anomalous behavior was occasionally observed, but the height at which it appears to begin is too great to be accounted for by cap formation. We conclude that errors in the computed height of the meteor may be responsible for the anomalies. A mean value for the effective ablation energy of 15.4 km2/sec2 was obtained, but individual meteors showed wide departures from this value. The mean mass of the meteors is estimated to be in the range 10−2–10−3 gram, corresponding to a visual magnitude of +5.

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Section: Theorymentioning

confidence: 97%

“…40 years. Contemporary reviews of this work have been given by Whipple [1943], Hawkins and Southworth [1958], Whipple and Hawkins [1959], McKinley [1961], and Verniani [1961]. The most useful treatise on the whole subject is that by Opik [1958].…”

Section: Theorymentioning

confidence: 99%

Radar observations of meteor deceleration

Evans¹

1966

J. Geophys. Res.

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“…The distribution is shown in Figure 3a' it has a high i•eak between +8 and +9 magnitude; this range includes 50% of all meteors. According to the classical theory of unfragmenting meteors, the maximum photographic luminous flux Ip• is given by [Verniani, 1961] where the ratio fi/p (fi is the ionizing probability of a meteor atom, and p is its mean atomic mass) was assumed equal to 2.6 • 10 -• v • cgs by following the result by Verniani and Hawkins [1964]. The dependence of the magnitude M on the ablation coefficient a is small, and so we can simplify (3) and (4), leaving only the explicit dependence of M,• and q,• on m•, v•, and Z• and taking a mean value for the rest of the expressions by using values of a and H• corresponding to v• = 40 •/sec (log a = --11.65; H, = 5.75 km).…”

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confidence: 99%

An analysis of the physical parameters of 5759 faint radio meteors

Verniani¹

1973

J. Geophys. Res.

135

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The results of an analysis of about 6000 meteors detected in 1962 from at least three different stations located around Havana, Illinois, under the Harvard Radio Meteor Project are presented. Each station yields instantaneous values of the meteor velocity υ and the electron line density q in the trail, thus permitting the determination of the mean deceleration and a sketch of the ionization curve. From the ionization curve we can compute the meteor mass m∞. It is then possible with the aid of some assumptions to derive values for the density and the ablation coefficient. The mean mass is about 10−4 gram. The mean velocity turns out to be rather low (34 km/sec) and confirms the existence of a systematic shift in the velocity distribution, depending upon the mass of the particles. The dependence of radio magnitudes M (i.e., maximum electron line densities qm) on the basic parameters of meteors (velocity, mass, and zenith angle ZR) turns out to be very close to the predictions of the single‐body theory. In fact, we find qm ∼ m∞0.9 υ∞3.9 cos ZR. However, meteors are on the average 1 magnitude brighter than predicted by the same theory and are about one‐half shorter in duration and length. Such results are ascribed to the common occurrence of fragmentation. Moreover, the dependence of all three characteristic heights on velocity is much less than expected, there is a very large discrepancy between observed and theoretical beginning heights, and high‐velocity meteors appear to ionize much lower than predicted by theory. The median value of the computed densities turns out to be 0.8 g cm−3, pointing out that the structure of radio meteors is as fragile as that of both ordinary photographic meteors and extremely large ones. Mean values of basic parameters for shower meteors do not differ significantly from the corresponding ones for sporadic meteors; thus a result previously obtained for photographic meteors having an average mass of 1 gram is confirmed. This lack of differentiation between sporadic and shower meteors is proof of the cometary origin of most meteors.

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“…where m is the meteoroid's mass, v its speed at maximum luminosity (which we take here to be equal to the atmospheric impact speed), and H the atmospheric density scale height (Hawkins and Southworth, 1958;Verniani, 1961). The index n is related to the luminous efficiency and is taken to be 1 for slow, dense meteoroids (Whipple, 1938) and −1 for fast, low-density meteoroids (Öpik, 1958) as defined above.…”

Section: Brightness and Height Of Venusian Meteorsmentioning

confidence: 99%

Prospects for meteor shower activity in the venusian atmosphere

Christou

2004

Icarus

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On meteor ablation in the atmosphere

Cited by 10 publications

References 20 publications

Radar observations of meteor deceleration

Radar observations of meteor deceleration

An analysis of the physical parameters of 5759 faint radio meteors

Prospects for meteor shower activity in the venusian atmosphere

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