Decoherence time scales for “meteoroid streams”

Abstract

Abstract-We explore the orbital dynamics of Earth-crossing objects with the intent to understand the time scales under which an "orbital stream" of material could produce time-correlated meteorite falls. These "meteoroid streams" have been suggested to be associated with three well-known meteoritedropping fireballs (Innisfree, Peekskill, and P¯Ìbram). We have performed two different analyses of the statistical significance of the "orbital similarity," in particular calculating how often orbits of the same level of similarity would come from a random sample. Secondly, we have performed extremely detailed numerical integrations related to these three cases, and we find that if they were streams of objects in similar orbits, then they would become "decoherent" (in the sense that the day-of-fall of meteorites of these streams become almost random) on time scales of 10 4 -10 5 yr. Thus, an extremely recent breakup would be required, much more recent that the cosmic ray exposure ages of the recovered falls in each case. We conclude that orbital destruction is too efficient to allow the existence of long-lived meteoroid streams and that the statistical evidence for such streams is insufficient; random fall patterns show comparable levels of clustering.

Probability of coincidental similarity among the orbits of small bodies – I. Pairing

“…In the present study, using the ideas described in Jopek & Froeschlé (1997); Jopek et al (2003) and in Pauls & Gladman (2005), we show how different factors can influence the assessment of the probability of chance grouping among the orbits taken from different data samples: bolides, video, and radio meteors. Also, we have scoped the probability of spurious pairing among the near Earth asteroids (NEAs).…”

“…To assess P 2 (see the idea proposed in Jopek & Froeschlé (1997)) it is sufficient to generate n sets of O orbits and find a number of sets k ≤ n in which at least one similar pair (A, B) was identified. Estimated probability is given as a relative frequency: Pauls & Gladman (2005) proposed interesting approach based on the geometric probability distribution i.e. the probability distribution of the number of X Bernoulli trials needed to get one success.…”

“…For given value of D c the probability of finding a spurious group of meteoroids of M members was assessed by the cluster analysis in the two hundred artificial orbital samples. In Pauls & Gladman (2005), to asses such probability the authors proposed interesting approach based on the geometric probability distribution of a series of Bernoulli trials. The authors developed a method for calculating the probability of random pairing among two orbits in a given orbital data set.…”

Properties of meteoroids from different classes of parent bodies

“…If they are part of a larger meteoroid stream, they challenge our understanding of asteroid structure, stream formation and evolution. Pauls & Gladman (2005), nevertheless, concluded on statistical basis that the orbital closeness of both meteorites can be explained by chance coincidence.…”

Far from random: dynamical groupings among the NEO population

“…In general, the results of our analysis are more consistent with secular resonances and the Kozai mechanism being the sources of most of the observed dynamical coherence; NEOs are being confined via resonances into specific paths with well-defined perihelia. It is now widely accepted that groups of objects moving initially in similar trajectories (debris resulting from breakups) lose all orbital coherence in a short time-scale (Pauls & Gladman 2005;Rubin & Matson 2008;Lai et al 2014). In contrast, objects confined by resonances can remain together, dynamically speaking, for longer time-scales and those that are lost can be easily replaced via resonant capture.…”