Luminous efficiency determination and its challenges

The luminous efficiency tau describes the fraction of lost kinetic energy of an entering object converted into brightness. This parameter is used to calculate a meteoroid's mass from its observed brightness. Presently, the luminous efficiency is part of current research and its determination based on several assumptions. Amongst others, different meteor parameters have to be assumed. They range from the shape of the meteoroid, which changes during the flight through the atmosphere, possible fragmentation, to the composition of the meteoroid as well as of the atmosphere, and aspects of the detection themselves. The data of FRIPON, the Fireball Recovery and InterPlanetary Observation Network, was used to calculate the luminous efficiencies of their recorded meteors. First, deceleration-based formulas for the mass computation of the corresponding meteoroids were used. Then, the recorded light curves were investigated to determine the luminous efficiencies. We found tau-values in the range of 0.0001% to 100%, whereas most are in the order of 0.1% to 10%. In this work we will briefly introduce the process of obtaining these values and point out its difficulties.