Optical trail widths of faint meteors observed with the Canadian Automated Meteor Observatory

Abstract

The optical trail widths of 30 faint meteors (average magnitude ∼+3, m ∼ 10 −4 kg) were resolved and measured using the Canadian Automated Meteor Observatory (CAMO). CAMO is an automated, high-resolution intensified digital video system capable of detecting meteors as faint as magnitude +5. The observatory’s two stations, separated by a baseline of 50 km, and each comprised of a narrow- and wide-field camera, observed the meteors for this survey. Data from the wide-field cameras were used to derive a trajectory solution for each meteor with the software package METAL, while data from the narrow-field cameras were used to measure trail widths with the image analysis software IMAGEJ. Raw widths were measured as a function of distance along the meteor trail for each frame of the video. To ensure that instrumental bloom did not artificially increase trail widths, the width of a star imaged with the narrowfield camera, with equivalent brightness to the meteor trail at the point of measurement, was subtracted from each observed raw width. Corrected trail widths up to 100 m at heights above 110 km were observed, varying with height as the inverse of atmospheric density. 14 of the 30 events were observed with both narrow-field cameras and each showed good agreement of trail width values after bloom correction. This suggested that the widths were true physical sizes, and not instrumental artefacts. Preliminary investigation suggests collisional de-excitation of energetic atoms is a plausible process for the formation of these wide trails.