Dynamic radio spectra from two fireballs

K. S. Obenberger, G. B. Taylor, C. S. Lin, J. Dowell, F. K. Schinzel and K. Stovall

Journal of Geophysical Research: Space Physics
120, 9916–9928
Version of Record online: 14 NOV 2015
DOI: 10.1002/2015JA021229


“We present dynamic spectra from the Long Wavelength Array telescope of two large meteors (fireballs) observed to emit between 37 and 54 MHz. These spectra show the first ever recorded broadband measurements of this newly discovered VHF emission. The spectra show that the emission is smooth and steep, getting very bright at lower frequencies. We suggest that this signal is possibly emission of Langmuir waves and that these waves could be excited by a bump-on-tail instability within the trail. The spectra of one fireball display broadband temporal frequency sweeps. We suggest that these sweeps are evidence of individual expanding clumps of emitting plasma. While some of these proposed clumps may have formed at the very beginning of the fireball event, others must have formed seconds after the initial event.”