On the Ionizing Efficiency of Meteors.

Abstract

This paper reviews the present knowledge on the ionizing efficiency of meteors ,r0 There is a considerable measure of disagreement among authors concerning both its order of magnitude and its dependence on the velocity. Since the luminous efficiency, Tp is known with a fair degree of accuracy, we have evaluated the ionizing efficiency from Tp and from Millman and McKinley's data relating durations of radio echoes and visual magnitudes. We find the ionizing efficiency proportional to v2 and the probability, p, that an atom ablated from a meteoroid will produce a free electron proportional to "4 From the results of the simultaneous photographic and radio observations of meteors by Davis and Hall and from the value of Tp, we find p = 0.01 at V = 32 km . Accordingly, we obtain p = 1 X 10-20 v4 and r0 = 6 X 10-12 V , with V expressed in m s- . The comparison of the rates of photographic and radio meteors of about the same magnitude confirms the proportionality p V . As a consequence, the relation between the magnitude and the electron line density of the trail is independent of the velocity.