Evolution of Meteoroid Streams Originating from NEA Collisions

The physical processes which may affect the evolution of meteor streams are discussed and a review is then given of the work carried out to date on the evolution of meteor streams. It is clear that they evolve principally due to the effect of planetary perturbations and radiation pressure. The formation of streams from the breakup of a comet is also discussed. All the evidence, including the recent, discovery of 1983TB points to the correctness of this hypothesis.

The physical processes which may affect the evolution of meteor streams are discussed and a review is then given of the work carried out to date on the evolution of meteor streams. It is clear that they evolve principally due to the effect of planetary perturbations and radiation pressure. The formation of streams from the breakup of a comet is also discussed. All the evidence, including the recent, discovery of 1983TB points to the correctness of this hypothesis.

Modern concepts of the formation and evolution of meteoroid streams formed by the disintegration of cometary nuclei are described. The action of planetary perturbations determining the evolution of meteoroid orbits is discussed. On an example of the calculation of secular orbital perturbations of the asteroid 2003HP32, the main regularities in variation of the orbital elements as well as of the radii-vectors of ascending and descending nodes are found. The dispersion of orbits increases with time, and meteoroid streams may generate up to eight meteor showers observed on the Earth depending on the orbit type of the parent comet. It was established that some meteoroid streams include large fragments of extinct cometary nuclei. These fragments being the members of meteoroid streams are identified among the near-Earth asteroids. Consequently, the meteoroid streams consist of not only small particles but also of large fireball-producing bodies. This fact is proved based on the example of three asteroid-meteoroid complexes revealed by the authors in recent years.

The overall objective of the thesis is to understand the long term orbital dynamics of comets and meteoroid streams. The initial idea focused mainly on detailed analysis of Jovian resonances in Orionids and Leonids. Special emphasis was given to study their influence in causing meteor outbursts and storms on Earth. The theoretical simulations matched with observational records to a very good degree. This work led to the curious question as to whether any resonance mechanism could be driven due to Saturn’s gravity. Subsequent analysis showed that Saturn’s influences can also become vital when the order of resonance (concerning Saturn) is smaller than that in the adjacent Jovian resonances. Compact resonant structures (due to Saturn’s effects) were identified in both Orionid and Leonid streams during present times. All these calculations were done solely using a Newtonian model. This raised more questions as to whether Einstein’s general relativistic effects could have any substantial role during long term (of the order of thousand years) meteor shower forecasts. Analytical and numerical analysis showed that general relativistic effects could lead to significant errors (in long term forecasts) in some particular combinations (or different epochs) of Keplerian orbital elements in certain low perihelion distance (below 0.15 AU) and low semi-major axis (below 1.5 AU) meteoroid streams. Because some low perihelion distance meteoroid streams are associated with sungrazing comets, this led to the next question regarding the reason for the absence of meteor showers from this class of comets. A detailed study using Lagrange’s planetary equations showed that most sungrazers cannot make the nodes of meteoroid particles Earth intersecting at low ejection velocities (of order 10 m/s). This can be used as a convincing argument to establish the absence of spectacular meteor showers on Earth from the frequently observed sungrazers so far.

Formation and past evolution of the showers of 96P/Machholz complex

Aspects of the formation and evolution of meteoroid streams formed during collisions of NEAs with objects of the Main Asteroid Belt are studied. This collision scenario is considered more probable, since many NEAs, due to their origin, cross the Main Belt region, in which the density of objects is much higher compared to the inner regions of the Solar System. The meteoroid streams originating from collisions have a number of differences from streams of cometary origin, both in terms of the formation of the stream and during further dynamic evolution.

On the evolution of the meteor streams

The existence of meteoroid streams is indicated by the regular appearance of coherent meteor activity at specified times during the year. Since it is the interaction of the meteoroid with the atmosphere that is detected, the meteoroid has to be greater than about 100 micrometers in radius. Observation of these interactions gives information on individual meteoroids as well as collective phenomena. It is generally agreed that streams form through the ejection of dust particles from the surfaces of comets and asteroids at speeds considerably lower than the orbital speed. The subsequent motion of these particles is affected by gravitational perturbations from the planets and the effects of solar radiation forces. This review is intended to present an overview of the development of the subject and of our current state of knowledge.

The orbit and evolution of the Geminid meteoroid stream

In this work we study formation and evolution of meteoroid streams originating from the collisions of near Earth asteroids (NEA) with objects of the Main Asteroid belt (MAB). Such a collision scenario is considered more probable compared to collisions between NEAs, since many NEAs, by virtue of their origin, cross the MAB region, where the number density of objects is significant compared to the inner regions of the Solar System. Meteoroid streams originating from collisions have a number of differences from the streams of cometary origin, both in terms of the formation and the evolution. In this paper, estimates are obtained for the meteoroid formation rate as a result of NEA collisions with MAB asteroids. On the basis of high-velocity collisions models and the DART experiment data, possible particle size and velocity distributions are obtained. We made numerical simulation taking into account gravitational perturbations and radiation forces and the influence of the initial velocity on the evolution was studied. An analysis was made of the rate of dust and meteoroids production, taking into account the distribution of the current population of the NEA, and it was concluded that the rates of influx of meteoroids of asteroid and cometary origin (in terms of mass) can be quite comparable.

Every day, large number of meteoroids enter the Earth’s atmosphere and deposit their mass either in atomic form or in ionic form depending on whether it has undergone ablation or fragmentation. The heavier meteoroids undergo fragmentation while the lighter ones are more prone to ablate. In this paper, we would like to speculate meteoroid stream structure of Leonid meteor shower based on fragmenting meteoroids. A 23 revolutions old meteoroid trail left behind by the comet 55P/Tempel-Tuttle in the year 1213 AD, which instigated Leonid meteor shower in the year 2010 is considered for our study. We have calculated mass of the meteoroids, echo durations and percentage of fragmentation. From the observed echo durations of meteoroids, estimated masses and from the percentage of fragmentation, we visualize the stream structure to be like the lighter particles wrapping up the heavier ones. The results we draw from these three different studies are matching with each other. To our knowledge, we are the first to speculate on the meteor stream structure based on fragmentation and making it a new tool in meteor stream evolution. Based on echo durations, it has been observed that 72% of the activity during the shower is contributed by lighter particles of the stream. It is found that about 20% of the meteoroids have undergone fragmentation indicating the minimal role of heavier particles (> $$10^{-6}$$ g) during Leonid Meteor Shower (LMS). The masses of the meteors are estimated to be in the range of $$10^{-10}$$ – $$10^{-5}$$ g.