Margaret Campbell-Brown University of Western Ontario Luminous efficiency Margaret Campbell-Brown University of Western Ontario

Luminous efficiency Fraction of kinetic energy emitted as light Depends on: Speed Composition of meteoroid Spectral response of detector Mass

Theoretical Optical observations Optical/radar Laboratory Artificial meteors

Past Work based on Weryk & Brown (2013)

Past Work Verniani (1965) Super Schmidt meteors drag equation + luminous intensity equation  luminous efficiency 361 meteors recorded by the Super Schmidt cameras Assumed follows τ = τ0vn n = 1.01 ± 0.15 τ0 is based on one meteor (and ‘confirmed’ by artificial meteor experiments)

Past Work Ayers et al. 1970 artificial meteors iron and nickel Assume follows τ = τ0vn Maximum speed 8 km/s n = 1.9 ± 0.4 rescaled in 1976 by Ceplecha & McCrosky

Past Work Becker & Friichtenicht (1971) & Becker & Slattery (1973) lab experiments Micron-sized projectiles of iron, copper, aluminum, silicon Not free molecular flow Up to 40 km/s

Past Work Weryk & Brown (2013) Simultaneous radar (CMOR) and optical (CAMO) Assume ionization efficiency of Jones (1997) is correct Suggest that video masses are an order of magnitude smaller than previous work

Difficulties Optical observations: need non-fragmenting meteors, precise decelerations Theoretical: Excitation cross sections not well known at meteor energies Radar/optical: need an ionization efficiency Lab experiments: need to have the right flow regime, range of materials Artificial meteors: expensive, only low speeds possible