Association Between Meteor Radio Afterglows and Optical Persistent Trains

Abstract

This paper presents the first observed association between meteor radio afterglows (MRAs) and persistent trains (PTs) and provides the first evidence of a link between these two phenomena. Coobservations of four meteor trails (trains) from the Long Wavelength Array (LWA) telescopes in New Mexico and the Widefield Persistent Train (WiPT) camera associate the long-lasting (tens of seconds), self-generated radio emission known as MRAs with the long-lasting (tens of minutes) optical emissions known as PTs. Each of the four MRAs presented in this paper were spatially and temporally coincident with a PT. In one case, the MRA follows a relatively small (≤400 m × 400 m) noticeably bright region (knot) of emission within the PT, whereas the other three cases were associated with broader regions of PT activity. As PTs are thought to be driven by exothermic chemical reactions between atmospheric oxygen and ablation products, we show that the same reactions, specifically those involving anions, may produce the necessary suprathermal electrons to power MRAs. We show that only one part in ∼10 10 of the available power needs to be converted to radio emission in order to produce a typical MRA.

Simultaneous broadband radio and optical emission of meteor trains imaged by LOFAR / AARTFAAC and CAMS

“…Of the proposed intrinsic emission scenarios, chemically produced suprathermal electrons (Obenberger et al, 2020) could cause lingering radiation over minutes timescale if those electrons are captured by atoms and molecules that slowly diffuse into the train. Other proposed mechanisms such as Langmuir waves (Obenberger et al, 2015), free-free emission (Filonenko, 2018) and transition radiation (Obenberger et al, 2020), would be expected strong in the meteor itself, but we see the radiation increase in intensity following the meteor head before fading.…”

“…Several mechanisms for broadband radio emission from meteors have been suggested in the literature, namely reflected broadband terrestrial radio emission, intrinsic emission from chemically produced suprathermal electrons (Obenberger et al, 2020), Langmuir waves (Obenberger et al, 2015), free-free emission (Filonenko, 2018) and transition radiation (Obenberger et al, 2020). Also, bright celestial radio emission shines on the meteor trains and that radiation may be scattered, as suggested in Obenberger et al (2015).…”

Broadband Imaging to Study the Spectral Distribution of Meteor Radio Afterglows

“…Using the radio data from LWA-SV and optical data from the Widefield Persistent Train Camera (WiPT), Obenberger et al (2020) has shown that the MRAs are temporally and spatially correlated with the long lasting (tens of minutes) emission in the optical and infrared known as persistent trains (PTs) (see, Borovička, 2006 for an overview). The PTs derive their energy from the continuous exothermic chemical reactions between the ablated meteoric metal particles and atmospheric oxygen species (Kruschwitz et al, 2001;Obenberger et al, 2020). This work demonstrates that persistent trains can provide enough suprathermal electrons to drive the MRA emission.…”

“…Using the radio data from LWA‐SV and optical data from the Widefield Persistent Train Camera (WiPT), Obenberger et al. (2020) has shown that the MRAs are temporally and spatially correlated with the long lasting (tens of minutes) emission in the optical and infrared known as persistent trains (PTs) (see, Borovička, 2006 for an overview). The PTs derive their energy from the continuous exothermic chemical reactions between the ablated meteoric metal particles and atmospheric oxygen species (Kruschwitz et al., 2001; Obenberger et al., 2020).…”

Broadband Imaging to Study the Spectral Distribution of Meteor Radio Afterglows

“…Using the radio data from LWA-SV and optical data from the Widefield Persistent Train Camera (WiPT), Obenberger et al (2020) has shown that the MRAs are temporally and spatially correlated with the long lasting emission in the optical and infrared known as persistent trains (Borovička, 2006). This work demonstrates that persistent trains can provide enough suprathermal electrons to drive the MRA emission.…”