Properties of Alpha Monocerotid meteors from the observation of the 2019 outburst in the Czech Republic

TL;DR

This study analyzed the 2019 Alpha Monocerotid meteor outburst in the Czech Republic, revealing unique properties such as consistent end heights and sodium deficiency, and suggesting a fragile, devolatilized cometary origin.

Contribution

First detailed observational analysis of the 2019 outburst, identifying unique meteor properties and proposing a new model for the meteoroids' composition and origin.

Findings

Meteor end heights are consistently at 90 km regardless of magnitude.

AMO meteoroids are deficient in sodium.

Radiants and orbits match the 1995 outburst data.

Abstract

We observed the predicted outburst of the Alpha Monocerotid (AMO) meteor shower on 2019 November 22 with our modernized video and photographic cameras. Due to the short duration and moderate intensity of the outburst, atmospheric trajectories and radiants were obtained for only ten meteors, seven of which included velocities, magnitudes, and orbits. In addition, one incomplete video spectrum was captured. The radiants and orbits were found to be compatible with that of the 1995 outburst. The spectrum confirmed that AMO meteoroids are deficient in sodium. Unlike any other meteor shower, meteor end heights were found to be distributed along a constant level of 90 km for all meteors with magnitudes between +4 and -2 and with atmospheric trajectory lengths up to 40 km. We propose that Alpha Monocerotids were formed from a devolatilized and fragile cometary crust composed from relatively large fundamental grains.