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

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.