Luminous efficiency of meteors derived from ablation model after assessment of its range of validity

Context. The luminous efficiency, tau, can be used to compute the pre-atmospheric masses of meteoroids from corresponding recorded meteor brightnesses. The derivation of the luminous efficiency is non-trivial and is subject to biases and model assumptions. This has led to greatly varying results in the last decades of studies. Aims. The present paper aims to investigate how a reduction in various observational biases can be achieved to derive (more) reliable values for the luminous efficiency. Methods. A total of 281 meteors observed by the Fireball Recovery and InterPlanetary Observation Network (FRIPON) are studied. The luminous efficiencies of the events are computed using an ablation-based model. The relations of tau as a function of the pre-atmospheric meteoroid velocity, v(e), and mass, M-e, are studied. Various aspects that could render the method less valid, cause inaccuracies, or bias the results are investigated. On this basis, the best suitable meteors were selected for luminous efficiency computations. Results. The presented analysis shows the limits of the used method. The most influential characteristics that are necessary for reliable results for the tau computation were identified. We study the dependence of tau on the assumed meteoroid's density, rho, and include improved rho-values for objects with identified meteoroid stream association. Based on the discovered individual biases and constraints we create a pre-debiased subset of 54 well-recorded events with a relative velocity change >80%, a final height <70 km, and a Knudsen number Kn < 0.01; this last value indicates that the events were observed in the continuum-flow regime. We find tau-values in the range between 0.012% and 1.1% for this pre-debiased subset and relations of tau to v(e) and M-e of: tau=7.33.v(e)(-1.10) and tau=0.28.M-e(-0.33). Conclusions. The derived luminous efficiency of meteoroids depends on the assumed material density. Our results indicate that the applied debiasing method improves the analysis of tau from decelerated meteoroids. The underlying method is only valid for meteors in the continuum-flow regime. These events tend to have low end heights, large masses, and high deceleration.

Automated summary

This study aims to reduce observational biases to obtain more reliable values for meteoroid luminous efficiency. By analyzing 281 meteors using an ablation-based model, influential characteristics for accurate results were identified. The results show that the derived luminous efficiency depends on the assumed material density, and the debiasing method improves the analysis of tau from decelerated meteoroids.