Lunar impact flashes from Geminids, analysis of luminous efficiencies and the flux of large meteoroids on Earth

TL;DR

This study analyzes lunar impact flashes from the Geminid meteor stream to estimate luminous efficiencies and infer the flux of large meteoroids impacting Earth, suggesting a downward revision of luminous efficiency and an increased influx estimate.

Contribution

It provides new estimates of luminous efficiency for Geminid impacts and compares them with previous values, impacting the understanding of meteoroid flux on Earth.

Findings

Luminous efficiency for Geminid impacts is estimated at 2.1x10$^{-3}$.

Luminous efficiency should be revised downward for sporadic impacts.

Increased influx of kilogram-sized meteoroids on Earth inferred.

Abstract

We analyze lunar impact flashes recorded by our team during runs in December 2007, 2011, 2013 and 2014. In total, 12 impact flashes with magnitudes ranging between 7.1 and 9.3 in V band were identified. From these, 9 events could be linked to the Geminid stream. Using these observations the ratio of luminous energy emitted in the flashes with respect to the kinetic energy of the impactors for meteoroids of the Geminid stream is estimated. By making use of the known Geminids meteoroid flux on Earth we found this ratio to be 2.1x10$^{-3}$ on average. We compare this luminous efficiency with other estimations derived in the past for other meteoroid streams and also compare it with other estimations that we present here for the first time by making use of crater diameter measurements. We think that the luminous efficiency has to be revised downward, not upward, at least for sporadic impacts. This implies an increase in the influx of kilogram-sized and larger bodies on Earth that has been derived thus far through the lunar impact flash monitoring technique.