共查询到20条相似文献，搜索用时 625 毫秒
1.
Josep M. Trigo-Rodríguez Esko Lyytinen Daniel C. Jones José M. Madiedo Alberto J. Castro-Tirado Iwan Williams Jordi Llorca Stanislav Vítek Martin Jelínek Blanca Troughton Francisco Gálvez 《Monthly notices of the Royal Astronomical Society》2007,382(4):1933-1939
The existence of asteroidal meteoroid streams capable of producing meteorite-dropping bolides has long being invoked, but evidence is scarce. Recent modelling of previously reported associations suggests that the time-scales to keep the orbital coherence of these streams producing meteorites are too short. We present an unequivocal association between near earth object (NEO) 2002NY40 and at least one bright fireball detected over Finland in 2006 August. Another two additional fireballs recorded from Spain and Finland seem to be related, together producing a fireball-producing stream (β Aquarids). On the basis of historical data, the 2006 finding suggests the existence of a meteoroid complex capable of producing meteorites. Taking into account present time-scales for orbital decoherence, if 2002NY40 has large meteoroids associated with it, such behaviour would be the consequence of a relatively recent asteroidal fragmentation. Supporting our claim, the heliocentric orbits of two recently discovered NEOs, 2004NL8 and 2002NY40, were found to exhibit a good similarity to each other and also to the orbits of the three bolides. The fireball spectra of the two Finish bolides showed that the chemical abundances of these objects are consistent with the main elements found in chondrites. This result is consistent with the probable Low iron, Low metal (LL) chondritic mineralogy of asteroid 2002NY40. Consequently, this asteroid may be delivering LL chondrites to the Earth. Additional fireball reports found in the literature suggest that the associated β Aquarid complex may have been delivering meteorites to the Earth during, at least, the last millennium. 相似文献
2.
Using a meteor orbit radar, a total of more than 2.5 million meteoroids with masses ∼10−7 kg have had orbits measured in the interval 2002-2006. From these data, a total of 45 meteoroid streams have been identified using a wavelet transform approach to isolate enhancements in radiant density in geocentric coordinates. Of the recorded streams, 12 are previously unreported or unrecognized. The survey finds >90% of all meteoroids at this size range are part of the sporadic meteoroid background. A large fraction of the radar detected streams have q<0.15 AU suggestive of a strong contribution from sungrazing comets to the meteoroid stream population currently intersecting the Earth. We find a remarkably long period of activity for the Taurid shower (almost half the year as a clearly definable radiant) and several streams notable for a high proportion of small meteoroids only, among these a strong new shower in January at the time of the Quadrantids (January Leonids). A new shower (Epsilon Perseids) has also been identified with orbital elements almost identical to Comet 96P/Machholz. 相似文献
3.
P. B. Babadzhanov 《Earth, Moon, and Planets》1996,72(1-3):305-310
Probably most meteor showers have a cometary origin. Investigation of Near-Earth asteroids' orbital evolution to determine whether they have related meteor showers is necessary to determine which asteroids evolved from comets. The results of calculations show that asteroid Orthos' orbit is an octuple Earth-crosser. Therefore, if Orthos has an old meteoroid stream it may produce eight meteor showers observable on the Earth. The existence of four Orthos' Northern meteor showers is confirmed by our search in the published catalogues of meteor radiants and orbits or in the archives of the IAU Meteor Data Center (Lund, Sweden). 相似文献
4.
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 meteorite‐dropping fireballs (Innisfree, Peekskill, and P?íbram). 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 104–105 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. 相似文献
5.
P. B. Babadzhanov 《Earth, Moon, and Planets》1995,71(3):305-310
Probably most meteor showers have a cometary origin. Investigation of Near-Earth asteroids' orbital evolution to determine whether they have related meteor showers is necessary to determine which asteroids evolved from comets. The results of calculations show that asteroid Orthos' orbit is an octuple Earth-crosser. Therefore, if Orthos has an old meteoroid stream it may produce eight meteor showers observable on the Earth. The existence of four Orthos' Northern meteor showers is confirmed by our search in the published catalogues of meteor radiants and orbits or in the archives of the IAU Meteor Data Center (Lund, Sweden). 相似文献
6.
P. B. Babadzhanov 《Earth, Moon, and Planets》1995,68(1-3):165-170
Probably the majority of meteor showers has a cometary origin. Investigation of Near-Earth asteroids' orbital evolution to determine whether they have related meteor showers are necessary to determine which asteroids evolved from comets. The results of calculations show that asteroid Orthos' orbit is an octuple Earth-crosser. Therefore, if Orthos has an old meteoroid stream it may produce eight meteor showers observable on the Earth. The existence of four Orthos' Northern meteor showers is confirmed by our search in the published catalogues of meteor radiants and orbits or in the archives of the IAU Meteor Data Center (Lund, Sweden). 相似文献
7.
Meteorites represent bodies at the larger end of the meteoroid size spectrum since they are large enough to survive ablation in the Earth’s atmosphere. They are thus far less numerous than normal meteoroids that become meteors. A number of meteorites can arrive at around the same time and location and so in some sense represent a stream, but these are just recent fragmentations. Most meteors, according to their cosmic ray exposure age are at least 10 million years old. This is roughly also the timescale for the onset of chaos in the inner Solar System and so conventional wisdom is that meteorites can not survive on such orbits for such a time span and that they certainly cannot survive as coherent streams. We investigate numerically the survival of streams for this time interval. 相似文献
8.
Martin Beech Simona Nikolova J. Jones 《Monthly notices of the Royal Astronomical Society》1999,310(1):168-174
Comet 15P/Finlay is unusual in that, contrary to ab initio expectations, it demonstrates no apparent linkage to any known meteor shower. Using data contained within the Electronic Atlas of Dynamical Evolutions of Short-Period Comets, we evaluate theoretical shower radiants for Comet 15P/Finlay, but find no evidence to link it to any meteoric anomalies in recorded antiquity. This result, however, must be tempered by the fact that any Comet 15P/Finlay-derived meteoroids will have a low, 16 km s−1 , encounter velocity with Earth's atmosphere. Typically, therefore, one would expect mostly faint meteors to be produced during an encounter with a Comet 15P/Finlay-derived meteoroid stream. We have conducted a D -criterion survey of meteoroid orbits derived from three southern hemisphere meteor radar surveys conducted during the 1960s, and again we find no evidence for any Comet 15P/Finlay-related activity. Numerical calculations following the orbital evolution of hypothetical meteoroids ejected from the comet, at each perihelion epoch since 1886, indicate that Jovian perturbations effectively 'drive' the meteoroids to orbits with nodal points beyond the Earth's orbit. The numerical calculations indicate that, even if Comet 15P/Finlay had been a copious emitter of meteoroids during the past 100 years, virtually none of them would have evolved into orbits capable of being sampled by the Earth. There are good observational data, however, to suggest that Comet 15P/Finlay is becoming a transitional comet–asteroid object, and that it has probably not been an efficient producer of meteoroids during the past several hundreds of years. 相似文献
9.
I. P. Williams 《Earth, Moon, and Planets》1996,72(1-3):321-326
The parent bodies of a number of major meteoroid streams are not in doubt and the orbits of these parents are also well determined. For these major streams individual orbits for a significant number of member meteoroids have also been determined. There is a significant spread in the determined values of the semi-major axis of individual meteoroids in a particular stream and this paper assumes that this spread is caused primarily by a variation in the ejection process and draws conclusions regarding the value of the ejection velocities from this. 相似文献
10.
I. P. Williams 《Earth, Moon, and Planets》1995,71(3):321-326
The parent bodies of a number of major meteoroid streams are not in doubt and the orbits of these parents are also well determined. For these major streams individual orbits for a significant number of member meteoroids have also been determined. There is a significant spread in the determined values of the semi-major axis of individual meteoroids in a particular stream and this paper assumes that this spread is caused primarily by a variation in the ejection process and draws conclusions regarding the value of the ejection velocities from this. 相似文献
11.
Martin Connors Paul Chodas Seppo Mikkola Paul Wiegert Christian Veillet Kimmo Innanen 《Meteoritics & planetary science》2002,37(10):1435-1441
Abstract— The newly discovered asteroid 2002 AA29 moves in a very Earth‐like orbit that relative to Earth has a unique horseshoe shape and allows transitions to a quasi‐satellite state. This is the first body known to be in a simple heliocentric horseshoe orbit, moving along its parent planet's orbit. It is similarly also the first true co‐orbital object of Earth, since other asteroids in 1:1 resonance with Earth have orbits very dissimilar from that of our planet. When a quasi‐satellite, it remains within 0.2 AU of the Earth for several decades. 2002 AA29 is the first asteroid known to exhibit this behavior. 2002 AA29 introduces an important new class of objects offering potential targets for space missions and clues to asteroid orbit transfer evolution. 相似文献
12.
Previous attempts to assign ordinary chondrites (OC) to meteoroid streams have been unsuccessful because the orbits of the proposed members had different radiants and, in some cases, the meteorites had significantly different cosmic-ray exposure (CRE) ages. Using more conservative criteria, we have identified four pairs of equilibrated OC (L6 Nejo, Salem; L6 Perpeti, Vouillé; L6 Drake Creek, Forsyth; H5 Okabe, Kerilis) wherein each member of the pair could conceivably have been derived from the same immediate precursor body (IPB). The members of each pair are of the same chondrite group and petrologic type; they have similar CRE ages and fell within 1 calendar day of each other (in different years). Because there is a moderate range in oxidation state (represented by mean olivine Fa) among equilibrated OC in each group, similarities in this intrinsic geochemical property between the members of two of the proposed pairs offer some support for the hypothesis that these rocks were derived from the same IPB. If the pairs are genuine, their precursor bodies were probably meter-size near-Earth asteroids (NEAs) with aphelia within or beyond the Main Asteroid Belt. Fragmentation of such NEAs is most likely to have occurred near aphelia; in principle, the ejecta could have spread somewhat along the NEAs’ orbits and collided with Earth on approximately the same calendar date but in different years. However, literature data show that, although ～670 meteorites with masses ≥10 kg reach the Earth’s surface each year, only five or six falls (typically in this mass range) are observed and recovered. This suggests that the chances of recovering more than one meteorite from a disrupted meter-size body in Earth-crossing orbit are small. It thus seems likely that the similar properties of the proposed OC pairs are due to coincidence. 相似文献
13.
We deal with theoretical meteoroid streams the parent bodies of which are two Halley-type comets in orbits situated at a relatively
large distance from the orbit of Earth: 126P/1996 P1 and 161P/2004 V2. For two perihelion passages of each comet in the far
past, we model the theoretical stream and follow its dynamical evolution until the present. We predict the characteristics
of potential meteor showers according to the dynamical properties of theoretical particles currently approaching the orbit
of the Earth. Our dynamical study reveals that the comet 161P/2004 V2 could have an associated Earth-observable meteor shower,
although no significant number of theoretical particles are identified with real, photographic, video, or radar meteors. However,
the mean radiant of the shower is predicted on the southern sky (its declination is about −23°) where a relatively low number
of real meteors has been detected and, therefore, recorded in the databases used. The shower of 161P has a compact radiant
area and a relatively large geocentric velocity of ∼53 km s−1. A significant fraction of particles assumed to be released from comet 126P also cross the Earth’s orbit and, eventually,
could be observed as meteors. However, their radiant area is largely dispersed (declination of radiants spans from about +60°
to the south pole) and, therefore, mixed with the sporadic meteor background. An identification with real meteors is practically
impossible. 相似文献
14.
P. B. Babadzhanov I. P. Williams G. I. Kokhirova 《Monthly notices of the Royal Astronomical Society》2008,386(4):2271-2277
Using the Everhart radau19 numerical integration method, the orbital evolution of the near-Earth asteroid 2003EH1 is investigated. This asteroid belongs to the Amor group and is moving on a comet-like orbit. The integrations are performed over one cycle of variation of the perihelion argument ω. Over such a cycle, the orbit intersect that of the Earth at eight different values of ω. The orbital parameters are different at each of these intersections and so a meteoroid stream surrounding such an orbit can produce eight different meteor showers, one at each crossing. The geocentric radiants and velocities of the eight theoretical meteor showers associated with these crossing points are determined. Using published data, observed meteor showers are identified with each of the theoretically predicted showers. The character of the orbit and the existence of observed meteor showers associated with 2003EH1 confirm the supposition that this object is an extinct comet. 相似文献
15.
The dynamical evolution of meteoroid streams associated with cornets Encke, Halley, Machholz 1986 VIII and asteroid Phaethon is discussed. It is shown that the planetary perturbations can greatly increase the streams thickness and each stream may produce several couples of meteor showers active in different seasons of the year. The theoretical and observed data are in a satisfactory accordance. 相似文献
16.
Three bright fireballs belonging to the August θ‐Aquillid (ATA) meteor shower were photographed by the Tajikistan fireball network in 2009. Two of them are classified as the meteorite‐dropping fireballs according to the determined parameters of the atmospheric trajectories, velocities, masses, and densities. Detection of the more dense bodies among cometary meteoroids points to a heterogeneous composition of the parent comet, and supports the suggestion that some meteorites might originate in the outer solar system, in the given case from the Jupiter‐family comet reservoir. A search for the stream's parent was undertaken among the near‐Earth asteroids (NEAs); as a result, the asteroid 2004MB6 was identified as a possible progenitor of the ATA meteoroid stream. Investigation of the orbital evolution of the 2004MB6 and the fireball‐producing meteoroid TN170809A showed that both objects have similar secular variations in the orbital elements during 7 kyr. The comet‐like orbit of the 2004MB6 and its association with the ATA shower suppose a cometary origin of the asteroid. 相似文献
17.
B. A. Lindblad 《Earth, Moon, and Planets》1995,68(1-3):397-404
A study of the Kappa Cygnid and other minor streams of the August epoch is presented based on a computer search in a sample of 3518 photographic meteoroid orbits. Four different meteoroid streams with radiants in Cygnus, Draco and Lyra, were found. Three of these: the Kappa Cygnids, the Alpha Lyrids and the Zeta Draconids are identified with meteor showers reported by nineteenth century visual observers. The fourth stream, the August Lyrids, consists of six meteors with radiants in Lyra centered on = 277°.6, = 46°.2. No previous visual reports of this stream have been found. It is interesting to note that all four meteoroid streams are coincident in time; their orbits are all of short period and they all have very nearly the same orientation of semi-major axis. 相似文献
18.
P.G. Welch 《Monthly notices of the Royal Astronomical Society》2001,328(1):101-111
A new search method for locating meteoroid streams within an orbit data base and obtaining their central core orbits is introduced. The method is based on the transformation of a data base of discrete orbits into a continuous density map. Artificial data bases are used to determine if a density is statistically unlikely to occur by random chance. A search is then run to identify all density peaks within the map that correspond to the central core of a meteoroid stream. Drummond D' criterion is used as a metric within the transformation and a D' acceptability limit, D l , defines the length scale over which a discrete meteor orbit can have an influence on the density map. Examination of the search dependence on D l for both real and artificial data sets indicates an appropriate standard value. A full search is run on 5280 meteor orbits from the IAU data base, detecting 16 known major and minor meteoroid streams. New central core orbits are presented for these. No major differences from the published orbits are detected, apart from possible multi-branched structure in the southern δ Aquarids. 相似文献
19.
Apostolos A. Christou Jeremie Vaubaillon Paul Withers 《Earth, Moon, and Planets》2008,102(1-4):125-131
We have simulated the formation and evolution of comet 1P/Halley’s meteoroid stream by ejecting particles from the nucleus
5000 years ago and propagating them forward to the present. Our aim is to determine the existence and characteristics of associated
meteor showers at Mars and Venus and compare them with 1P/Halley’s two known showers at the Earth. We find that one shower
should be present at Venus and two at Mars. The number of meteors in those atmospheres would, in general, be less than that
at the Earth. The descending node branch of the Halley stream at Mars exhibits a clumpy structure. We identified at least
one of these clumps as particles trapped in the 7:1 mean motion resonance with Jupiter, potentially capable of producing meteor
ourbursts of ZHR∼1000 roughly once per century. 相似文献
20.
The orbital evolution of the two meteorites Příbram and Neuschwanstein on almost identical orbits and also several thousand
clones were studied in the framework of the N-body problem for 5,000 years into the past. The meteorites moved on very similar
orbits during the whole investigated interval. We have also searched for photographic meteors and asteroids moving on similar
orbits. There were five meteors found in the IAU MDC database and six NEAs with currently similar orbits to Příbram and Neuschwanstein.
However, only one meteor 161E1 and one asteroid 2002 QG46 had a similar orbital evolution over the last 2,000 years. 相似文献