Resonance Electromagnetic Effect of the Kamchatka Meteoroid

Abstract

A large meteoroid entered the terrestrial atmosphere and exploded at an altitude of 26 km between the Kamchatka Peninsula and Alaska (geographic coordinates 56.9° N, 172.4° E) over the Bering Sea at 23:48:20 UT on December 18, 2018. The meteoroid has been named the Kamchatka (or Bering Sea) meteoroid. Its basic parameters are as follows: calculated total impact energy 173 kt of TNT, total optical radiated energy 1.3 × 10¹⁴ J, mass 1.41 kt, speed 32 km/s, size 9.4 m, and the trajectory directed at an angle of 68.6° with respect to the horizon. The entry of the Kamchatka meteoroid into the atmosphere was accompanied by the generation of a transient resonance electromagnetic signal in the 25–35 mHz band observable in the vicinity of the meteoroid explosion and in the magnetically conjugate region. Oscillations with amplitudes of 0.2–0.8 nT were observed over a 7-min interval. This study is aimed at analyzing the observations of the resonance electromagnetic effect from the Kamchatka meteoroid and discussing a mechanism for this effect. The resonance effect in the Earth’s magnetic field is analyzed using data with a time resolution of 1 s and an amplitude resolution of 1 nT from the database collected by the Intermagnet magnetometer network of magnetic observatories. The distance between the site of the meteoroid explosion and the magnetic observatories ranges from 1000 to 5000 km in the Northern Hemisphere and from 9010 to 12 425 km in the Southern Hemisphere. It is established that the only feasible mechanism is associated with the magnetic field displacement in the magnetosphere by the explosive impact of the celestial body, whereas only a negligibly small part of the meteoroid’s energy is spent on the generation of magnetic field perturbations. The meteoroid’s energy losses are similar to the losses in the reactive components of the radio frequency circuits, i.e., they return into the system. The oscillations cease after the meteoroid flies by, and the system returns into the initial state. The main results are summarized as follows. The resonance electromagnetic oscillations arose at 13 and 3 min prior to the Kamchatka meteoroid explosion. The duration of each observed perturbation is close to 7 min. The parameters of the quasi-periodic perturbations are similar to the parameters of magnetic Pc3 pulsations; however, they occured in the Y component of the magnetic field rather than in the X component of the magnetic field. Their observed periods are in the range of 33–36 s, and the amplitudes are in the range of 0.4–0.9 nT. Similar resonance oscillations were also recorded in the magnetically conjugate region. A mechanism for generating the resonance oscillations is proposed. The essence of the mechanism is that the meteoroid explosively impacts the magnetosphere and deforms the magnetic field lines that begin to oscillate at their eigenfrequencies. Depending on the McIlwain L-shell, the calculated period of oscillations is 19–169 s. For example, a period of 28–34 s is obtained with setting L ≈ 3–3.2, which is close to the observed period of 30 s. The generation of the resonance oscillations consumes approximately 10^–4 parts of the meteoroid kinetic energy.