Activity of the 1998 Leonid shower from video records

Abstract

Abstract— Video observations of the Leonid shower aboard two aircraft in the 1998 Leonid multi‐instrument aircraft campaign and from ground locations in China are presented. Observing at altitude proved particularly effective, with four times higher rates due to low extinction and low angular velocity at the horizon. The rates, derived from a total of 2500 Leonid meteors, trace at least two distinct dust components. One dominated the night of 1998 November 16/17. This two‐day wide component was rich in bright meteors with r = N (m + 1)/N (m) ≈ 1.5 (s = 1.4) and peaked at an influx of 3.1 ± 0.4 × 10−12 m−2 s−1 (for particles of mass <7 × 10−5 g) at solar longitude Λ0 ≈ 234.52 (Eq. J2000). The other more narrow component peaked on 1998 November 17/18 at Λ0 = 235.31 ± 0.01. Rates were elevated above the broad component between Λ0 = 235.15 and 235.40, symmetric around the current node of the parent comet 55P/Tempel‐Tuttle, peaking at 5.1 ± 0.2 × 10−12 m−2 s−1. The population index was higher, r = 1.8 ± 0.1 (s = 1.7), but not as high as in past Leonid storms (r = 3.0). The flux profile of this component has an unusual asymmetric shape, which implies a blend of contributions from at least two different but relatively recent epochs of ejection. The variation of r across the profile might be due to mass‐dependent ejection velocities of the narrowest component. High rates of faint meteors occurred only in an isolated five‐minute interval at Λ0 = 235.198, which is likely the result of a single meteoroid breakup in space.