Off-site articles pertaining to the Taurid Complex:

Abstract

Observational evidence is sought that the long-term (10^4 yr) action of a mean motion resonance with Jupiter can produce structure in a meteoroid stream, concentrating meteoroids in a dense swarm. More specifically, predictions tabulated by Asher & Clube of enhanced meteor and fireball activity from a Taurid Complex swarm in the 7:2 resonance are compared with observational data collected in Japan over several decades. The swarm model was proposed for reasons independent of the observations analysed here, and these newly considered data are shown to be consistent with it. This allows increased confidence in the Taurid swarm theory, and more generally could mean that resonant trapping is a dynamical mechanism affecting a significant amount of meteoroidal material in the inner Solar system.

Abstract

We show that a statistically significant number of Earth-crossing asteroids are part of the Taurid Complex of interplanetary objects. We also identify another group which appears aligned with (2212) Hephaistos. In addition, we describe the kind of orbital evolution that such asteroids undergo and consider the implications for the history of these two complexes, which may have a common origin.

Key words: comets: individual: P/Encke - comets: individual: Taurid Complex progenitor - meteoroids - minor planets

Abstract

It is shown that the giant comet breakup hypothesis has a clear basis in astronomical fact and, contrary to LaViolette's claims, is consistent with the available geochemical evidence. The importance of further trace element studies in polar ice for testing this hypothesis is, however, emphasized.

Abstract

Recent astronomical data are employed to make a detailed analysis of periodic terrestrial bombardment by molecular cloud debris during revolution around the Galaxy. Passage through the Gould Belt 3-6 Myr ago would have resulted in glaciation, geomagnetic reversals, and extinction events, all of which have left evidence. The break up of large comets in the solar system after passage through the Belt would produce a large dust and meteor input to the atmosphere, causing a rise of up to 1 percent of C-14 in the atmosphere. The level would be sufficiently high to affect a full climatic cycle. Some glaciation could also occur, and the last Ice Age could have been caused by the progenitor of comet Encke, part of which was the Tunguska meteorite, an interstellar object. It is estimated that further debris from the zodiacal cloud will intersect earth during the period 2000-2400 AD.

Abstract

Numerical integrations are performed on test-particle orbits similar to those of 2P/Encke and (6063) Jason. For purely gravitational integrations, or integrations with non-gravitational forces applied of a magnitude similar to those currently observed for 2P/Encke, the orbits do not alter substantially, all remaining decoupled from Jupiter. By using non-gravitational forces about four times as strong, which are plausible given 2P/Encke's known history as a prolific producer of meteoroids and dust, it is found that some orbits become Jupiter-crossers. It is not necessary for the non-gravitational forces to be exceptionally strong, nor to act consistently in one direction for an extended period, to produce such a result. Rather, the importance of the non-gravitational forces lies in them causing the semimajor axes of the test orbits to scan across the complex of jovian and saturnian mean motion resonances at 2.3<<e1>a<</e1>2.9 au, residence in strong resonances leading to enhanced secular orbital changes. By appealing to a reversal of the arrow of time one can then hypothesize that the sub-jovian orbit of 2P/Encke was achieved through the opposite process. This result also has implications for the origin of Apollo-Amor asteroids derived from de-volatilized cometary nuclei.

Abstract

If the Taurid Complex asteroids (plus 2P/Encke) are derived from the fragmentation of a giant comet over the past 20-30 kyr, as we have suggested elsewhere, then we need to identify some mechanism which could cause the observed dispersion in semimajor axes (1.8<<e1>a<</e1>2.6 au), eccentricities (0.64<<e1>e<</e1>0.85), and longitudes of perihelion (100 deg<omega<190 deg) the range in inclinations (i) is easily producible by secular perturbations. The problem devolves to one of identifying a source for the variations in a and e since, for a range of values of those parameters, differential precession will lead to a spreading in omega. Here we show that, considering only gravitational effects for variational orbits based on those of 2P/Encke, 5025 P-L and (6063) Jason, chaotic dynamical evolution over 30 kyr produces alterations in a and e which are insufficient to match the observed spread, suggesting that the asteroids concerned cannot have been derived from the splitting of a parent asteroid (i.e., inert object) on such a time-scale. However, plausible non-gravitational forces modelled quantitatively upon the observed motion of 2P/Encke can explain the spread, which may be interpreted as being supportive of our hypothesis of a cometary origin for the asteroids in the complex. Such forces also allow a connection with the Hephaistos group of objects to be made.

Abstract

The structure of the Taurid meteoroid complex is investigated using orbital element measurements from the IAU Meteor Data Center. The complex is found to have been formed during the last about 10 kyr, this time-scale corresponding to a probable late stage in the evolution of the parent object, a giant comet which was apparently captured into a small-perihelion, short-period orbit about 20 kyr ago and which, in an initial highly active phase, gave rise to the material that now broadly constitutes the zodiacal cloud. Models of the evolution of the complex under gravitational perturbations suggest that meteoroids must have originally left the parent object near perihelion, but also allow the possibility that fragmentations have occurred when large disintegration products collided with objects in the asteroid belt. Such a model may be entertained, for example, if the core of the evolved giant comet has previously undergone devolatilization, producing a high degree of fragility in the constituent debris.

Abstract

The contributions of P/Halley and other comets to the meteor streams are discussed. Particular attention is given to the meteoric production by P/Encke as the potential major contributor to the meteoric complex in the inner part of the solar system. The density and total mass of the meteoric stream associated with P/Encke is derived, taking into account the whole complex both of the showers and of the very broad and diffuse stream of seemingly sporadic meteoroids, produced by P/Encke in its long history via its showers.

Key words: P/Encke's stream - meteoric production by comets - meteoric influx

Abstract

Cometary dust trails furnish insight into the nature, origin, and evolution of comets, as well as into the relationship of comets to both asteroids and the zodiacal dust complex. A several years-long effort has been made to identify all dust trails detected over the course of IRAS observations, as well as to ascertain the comets' parent bodies. On the basis of a total of eight trails associated with known short-period comets, it is inferred that the trail phenomenon is common to all comets of this type; it is further conjectured that spaceborne IR detectors will observe a different ensemble of trails, as other comets pass perihelion.

Abstract

In 1983, the Infrared Astronomical Satellite discovered two pairs of dust bands, straddling the ecliptic plane and located in the asteroid belt. New analysis of the IRAS data has resulted in the detection of as many as eight additional bands, spread over more than 40 deg of ecliptic latitude. Dust band morphology is found to vary between different band pairs, having a typical apparent width of a few degrees. This limits the total number of bands which can be distinguished to near the number observed. The Tempel 2 and Encke dust trails are observed to extend over much more of their orbits than had been previously reported, and a new type of dust trail is found which has a relatively large angular width and no imbedded cometary source.

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