Meteoroid rotation and quasi-periodic brightness variation of meteor light curves

TL;DR

This study models how meteoroid rotation affects meteor brightness variations, using shape-specific forces and applying the model to real fireball data to infer meteoroid rotation and shape.

Contribution

It introduces a novel approach linking meteoroid shape and rotation to light curve flickering, aiding in pre-atmospheric characterization of meteoroids.

Findings

Rotation influences brightness flickering in meteor light curves.

Shape-dependent aerodynamic forces can diagnose meteoroid rotation.

Model successfully applied to observed fireball data.

Abstract

Meteor light curves are sometimes known to display flickering: rapid, quasi-periodic variations in brightness. This effect is generally attributed to the rotational modulation of the ablation rate, which is caused by the time-varying cross section area presented by a nonspherical rotating meteoroid to the oncoming airflow. In this work we investigate the effects that the rotation of a meteoroid of given shape (spherical, cubic, or cylindrical) has on the meteor's light curve, given state-of-the-art experimental laboratory estimates of the drag and lift coefficients of hypersonic flow (Mach number > 5) around various shaped objects. The meteoroid's shape is important in determining these two forces, due to the different response of the drag and lift coefficients according to the angle of attack. As a case study, the model was applied to a fireball observed on 2018 April 17 by the PRISMA network, a system of all-sky cameras that achieves a systematic monitoring of meteors and fireballs in the skies over the Italian territory. The results show that this methodology is potentially able to yield a powerful diagnostic of the rotation rate of meteoroids prior to their encounter with the atmosphere, while also providing essential information on their pre-fall actual shapes.