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(meteorobs) Electrophonic Sounds - Review of witness reports


Dear meteor observers,

the upcoming Leonids provide a great opportunity to potentially witness 
one very rare astronomical phenomenon: electrophonic sounds from meteors.

In contrast to "ordinary" meteor sounds, which have a time lag between the 
sound and the meteor appearance, the electrophonic (or anomalous) meteor 
sounds appear simultaneously with the meteor. 

It is so little known about the phenomenon that witness reports still play 
an important role in studying the phenomenon. Thus, two years ago we 
started with the Global Electrophonic Fireball Survey (GEFS), a project 
that collects witness reports of this rare phenomenon.

The first review of almost 100 reports collected by GEFS is now publicly 
available at: http://www.gefsproject.org/publications

The witness reports are also available at the same web-address (for 
further details see our review paper).

The result of statistical analysis revealed some interesting and 
previously unknown aspects of the phenomenon. Basically, a new overall 
picture of the phenomenon emerged from this study, with very important 
consequences for the theoretical efforts since the current theories can 
not explain these results. 

The paper is submitted to WGN, the Journal of the IMO, and the abstract is 
attached in the end of this e-mail. For more details visit the project's 
web-pages at www.gefsproject.org, and, in a case you hear such a sound 
during the Leonids, please, submit your report at:
http://www.gefsproject.org/form

Thank you and good luck with your Leonid observations!

  Dejan Vinkovic

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Vinkovic, D., Garaj, S., Lim, P. L., Kovacic, D., Zgrablic, G., Andreic, 
Z. "Global Electrophonic Fireball Survey: a review of witness reports - I. 
", submitted to WGN

ABSTRACT: "Despite more than 300 years since its first scientific 
          description, the phenomenon of electrophonic sounds from meteors 
          are still eluding complete physical explanation. According to 
          the accepted knowledge, the sound itself is created by strong
          electric fields on the ground induced by the meteor.
          Nonetheless, there is no convincing theory that can fully
          explain how a meteor can generate such a strong electric
          field. Extreme rareness of the phenomenon has prevented a
          substantial experimental work so far; thus, consequently, it
          remains on the margins of scientific interest. This is quite
          unfortunate since these electric fields suggest existence of a
          highly complex electromagnetic coupling and charge
          dynamics between the meteors and the ionosphere.
          Therefore, the existing theoretical work relies mostly on the
          witness reports. The Global Electrophonic Fireball Survey
          (GEFS) is the first systematic survey of witness reports of
          these sounds with a standardized questionnaire designed
          exclusively for this phenomenon. Here we present the overall
          picture of the phenomenon that emerged after almost 100
          reports collected by GEFS. It becomes clear now that the lover
          meteor brightness limit is about -2m, suggesting a bias in the
          existing electrophonic sounds catalogues toward brighter
          meteors. In contrast to the current belief that such low
          brightness electrophonic meteors produce transient sounds,
          we find that they can also produce sustained sounds. The
          current theories can not accommodate these results. We
          revive the old idea that the electrophonic sounds can be
          created by the corona discharge mechanism, in addition to the
          existing prevalent suggestion of resonant vibration of objects
          on the ground. "

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Department of Physics and Astronomy  | Center for Computational Sciences 
University of Kentucky               | University of Kentucky
177 CP-bldg                          | 325 McVey Hall
Lexington, KY 40506-0055             | Lexington, KY 40506-0045
e-mail: dejan@padot ukydot edu             | e-mail: dejan@ccsdot ukydot edu
http://www.padot ukydot edu/~dejan         | http://www.ccsdot ukydot edu/~dejan

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