Leonid electrophonic bursters

Beech, Martin; Foschini, L.

doi:10.1051/0004-6361:20000436

Cited by 15 publications

(5 citation statements)

References 20 publications

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“… Beech and Foschini [2001], however, applied EB theory to the Leonids. According to their calculations, our electrophonic meteors can be explained by EB theory, albeit only if they emit EM radiation at the moment of the airburst and by reaching altitudes below 90 km.…”

Section: Discussionmentioning

confidence: 99%

Instrumental recording of electrophonic sounds from Leonid fireballs

et al. 2002

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Electrophonic meteor sounds, heard simultaneously with the meteor appearance, are a longstanding problem due to their nonintuitive nature. Previous investigations have been undermined by lack of instrumental recordings. Here we present the first instrumental detection of electrophonic sounds obtained during the observation of 1998 Leonids from Mongolia. Two Leonid fireballs of brightness −6.5m and −12m produced short, low‐frequency sounds, which were simultaneously recorded by microphones in a special setup and heard by different observers. Simultaneous measurements of electromagnetic ELF/VLF radiation above 500 Hz did not reveal any signal correlated to the electrophonic event. The lack of signal was explained by the low frequency of electrophones. We show that physical characteristics of Leonid electrophones cannot be completely explained by existing theories and that further theoretical refinement and observational work is needed. Finally, we tentatively suggest the possibility of stronger than expected coupling of fireballs with atmospheric charge dynamics and ionosphere.

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Section: Discussionmentioning

confidence: 99%

Instrumental recording of electrophonic sounds from Leonid fireballs

et al. 2002

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“…However, none of the above mentioned authors considered that the gas envelope around any cosmic body entering the Earth's atmosphere is in the state of plasma, in which there are electric and magnetic fields (see e.g., Beech & Foschini 1999) limiting the degree of freedom of particles. According to the law of equipartition of energy, the specific heat ratio can be written (Landau & Lifshitz 1980):…”

Section: Calculation Of the Geocentric Speedmentioning

confidence: 99%

Probable asteroidal origin of the Tunguska Cosmic Body

Farinella

Foschini²,

Froeschlé

et al. 2001

A&A

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Abstract. The complete characterisation of the Tunguska event of 30th June 1908 is still a challenge for astrophysicists. We studied the huge amount of scientific literature to select data directly available from measurements and we introduced parameters calculated by the application of models, and evaluated other possibilities. We then selected a range of meaningful atmospheric trajectories, from which we extracted a set of possible orbits. We obtained 886 orbits, which were used to estimate the probabilities of the possible origin of the Tunguska Cosmic Body (TCB). We found that the probability that the TCB moved on an asteroidal path is higher than it moved on a cometary one, 83% to 17%, respectively.

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“…Keay [] suggested explosive disintegration of a fireball as the source of VLF. Beech and Foschini [, ] proposed a charge separation driven by a shock wave. Another charge separation mechanism was suggested by Bronshten [] during ablation of the meteor.…”

Section: Previous Theoretical Workmentioning

confidence: 99%

On the electrophonic generation of audio frequency sound by meteors

Kelley

Price

2017

Geophysical Research Letters

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Recorded for centuries, people can hear and see meteors nearly concurrently. Electromagnetic energy clearly propagates at the speed of light and converts to sound (called electrophonics) when coupled to metals. An explanation for the electromagnetic energy source is suggested. Coma ions around the meteor head can easily travel across magnetic field lines up to ~120 km. The electrons, however, are tied to magnetic field lines, since they must gyrate around the field above ~75 km. A large ambipolar electric field must be generated to conserve charge neutrality. This localized electric field maps to the E region then drives a large Hall current that launches the electromagnetic wave. Using antenna theory and following, a power flux of over 10−8 W/m2 at the ground is found. Electrophonic conversion to sound efficiency then needs to be only 0.1% to explain why humans can hear and see meteors nearly concurrently.

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Leonid electrophonic bursters

Cited by 15 publications

References 20 publications

Instrumental recording of electrophonic sounds from Leonid fireballs

Instrumental recording of electrophonic sounds from Leonid fireballs

Probable asteroidal origin of the Tunguska Cosmic Body

On the electrophonic generation of audio frequency sound by meteors

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