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1.
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
2.
中国古代火流星记录的统计分析 总被引：1，自引：0，他引：1
柳卸林 《中国天文和天体物理学报》1987,(3)
本文对中国古代火流星记录,按年统计,用功率谱这一数学方法对它们进行分析。结果发现声音是衡量火流星起源的一个重要参数。有声音的火流星具有170.6±0.0,102.4±0.0,66.1±2.2,27.3±0.4,23.3±0.0,17.9±0.4,14.8±0.1,12.4±0.1,10.5±0.3年的可能周期。有声火流星与陨石坠落周期基本相同,是与陨石同源的,来自小行星带。我们认为影响有声火流星和陨石下落的因素是太阳辐射引起的Yarkovsky效应和木星摄动。有声火流星的10.5±0.3,23.2±0.0,66.1±2.2年周期与Yarkovsky效应有关。12.4±0.1,17.9±0.4,102.4±0.0,170.6±0.0周期与木星摄动有关。至于14.8±0.1,27.3±0.4的周期,可能是木星摄动与Yarkovsky效应联合作用或其他原因所致。 相似文献
3.
The structures of the meteor streams of cometary origin—Draconids, Ursids, Perseids, and Lyrids—and the streams presumably connected with asteroids—Taurids and α-Capricornids—are compared. The comparative analysis was performed by the mass distribution of meteoroids in the stream and the activity profile for the meteors with the maximum recorded stellar magnitude +3 m and brighter. Visual observations of 1987–2008 from the database of the International Meteor Organization (IMO) and earlier sources were considered. It has been shown that the structures of the meteor streams of cometary and, presumably, asteroidal origin differ somewhat by the activity profile and the mass distribution of meteoroids in the cross-section of a stream along the Earth’s orbit. 相似文献
4.
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
5.
Yue-hua Ma You-wen He Pin-xin Xu Hai-bin Zhao 《Chinese Astronomy and Astrophysics》2008,32(2):186-196
During the first international joint observation of the Leo strong meteor shower, multidisciplinary and multi-media synthetic observation of Leo and Draco strong meteor showers and their catastrophic space weather events were carried out. The comprehensive analysis of the observed and related data of the Leo, Perseus and Draco strong meteor showers obtained for near half a century (from 1957 to 2003) fully verifies that the non-sporadic periodic strong meteor shower may lead to catastrophic space weather events. Preliminary identification is made of the following: the mechanism of formation of strong meteor showers, the law of occurrence of the fbEs abnormal peak and serious safety hazards for astronavigation. Also discussed in this paper are the evolutionary process of cometary dust, the law of occurrence and loss of cosmic dust storm and the mechanism of maintaining cosmic dust in the mid-latitude Es layer. 相似文献
6.
We present the results of a study of meteoroid bulk densities determined from meteor head echoes observed by radar. Meteor
observations were made using the Advanced Research Projects Agency Long-Range Tracking And Instrumentation Radar (ALTAIR).
ALTAIR is particularly well suited to the detection of meteor head echoes, being capable of detecting upwards of 1000 meteor
head echoes per hour. Data were collected for 19 beam pointings and are comprised of approximately 70 min. of VHF observations.
During these observations the ALTAIR beam was directed largely at the north apex sporadic source. Densities are calculated
using the classical physical theory of meteors. Meteoroid masses are determined by applying a full wave scattering theory
to the observed radar cross-section. Observed meteoroids are predominantly in the 10−10 to 10−6 kg mass range. We find that the vast majority of meteoroid densities are consistent with low density, highly porous objects
as would be expected from cometary sources. The median calculated bulk density was found to be 900 kg/m3. The orbital distribution of this population of meteoroids was found to be highly inclined. 相似文献
7.
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
8.
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
9.
Conventional ablation theory assumes that a meteoroid undergoes intensive heating during atmospheric flight and surface atoms
are liberated through thermal processes. Our research has indicated that physical sputtering could play a significant role
in meteoroid mass loss. Using a 4th order Runge-Kutta numerical integration technique, we tabulated the mass loss due to the
two ablation mechanisms and computed the fraction of total mass lost due to sputtering. We modeled cometary structure meteoroids
with masses ranging from 10−13 to 10−3 kg and velocities ranging from 11.2 to 71 km s−1. Our results indicate that a significant fraction of the mass loss for small, fast meteors is due to sputtering, particularly
in the early portion of the light curve. In the past 6 years evidence has emerged for meteor luminosity at heights greater
than can be explained by conventional ablation theory. We have applied our sputtering model and find excellent agreement with
these observations, and therefore suggest that sputtered material accounts for the new type of radiation found at great heights. 相似文献
10.
流星监测网是小尺寸近地小天体撞击监测、判断陨石落点的主要工具. 提出了一种基于多站布局的全天视频相机组网监测系统, 并在江苏及周边构建了一个区域级原型系统, 实现了火流星监测组网控制、视频数据采集、数据处理及流星体定轨的完整流程. 通过1yr的实测运行表明, 该系统可观测流星极限视星等为-1.0等, 可以实现绝对星等-2.5等流星的完备检测; 根据监测数据得到火流星通量为2.68×10-7km-2 ·h-1;群流星和偶发流星占比分别为46%和54%,偶发流星中类小行星轨道和类彗星轨道比例分别为27.1%和72.9,统计结果与国际主要流星监测网相接近,验证了监测网系统在实际组网使用中的监测能力. 相似文献
11.
Peter Brown Valerie Marchenko Danielle E. Moser Robert Weryk William Cooke 《Meteoritics & planetary science》2013,48(2):270-288
We propose that the Taurid meteor shower may contain bodies able to survive and be recovered as meteorites. We review the expected properties of meteorite‐producing fireballs, and suggest that end heights below 35 km and terminal speeds below 10 km s?1 are necessary conditions for fireballs expected to produce meteorites. Applying the meteoroid strength index (PE criteria) of Ceplecha and McCrosky (1976) to a suite of 33 photographically recorded Taurid fireballs, we find a large spread in the apparent meteoroid strengths within the stream, including some very strong meteoroids. We also examine in detail the flight behavior of a Taurid fireball (SOMN 101031) and show that it has the potential to be a (small) meteorite‐producing event. Similarly, photographic observations of a bright, potential Taurid fireball recorded in November of 1995 in Spain show that it also had meteorite‐producing characteristics, despite a very high entry velocity (33 km s?1). Finally, we note that the recent Maribo meteorite fall may have had a very high entry velocity (28 km s?1), further suggesting that survival of meteorites at Taurid‐like velocities is possible. Application of a numerical entry model also shows plausible survival of meteorites at Taurid‐like velocities, provided the initial meteoroids are fairly strong and large, both of which are characteristics found in the Taurid stream. 相似文献
12.
We tested four criteria used for discrimination between asteroidal and cometary type of orbits: Whipple criterion K, Kresak
criterion Pe, Tisserand invariant T and aphelion distance Q. To estimate their reliability, all criteria were applied to classify
the 2225 orbits of NEAs and 582 orbits of comets, for several epochs spanning the time interval of 40 thousands years. The
Q-criterion produced the smallest number of exceptions and has shown the best stability. The biggest number of exceptions
and the biggest variations are obtained for the K-criterion. We applied the Q-criterion to classify meteor orbits from the
IAU Meteor Data Center and the video meteor orbits available on the Web sites. Among the sporadic radar orbits, as well as
among the mean orbits of meteor streams a strong preponderance of asteroid-type orbits was observed. In case of the photographic
and video meteors a weak preponderance of cometary and asteroidal orbits was found, respectively. 相似文献
13.
We discuss a new method for measuring the coordinates of meteor shower radiants from meteor radar data. The method uses a high accuracy of radar goniometer measurements of one of the angular coordinates for meteor radiants and collective properties of incident meteor showers. It is based on a computer technology of searching for the coordinates of radiants using the intersections of meteor position lines on the celestial sphere and filtering nonrandom combinations of these intersections. The method allows the following: to detect meteor showers with a rate of more than 5 per day of observations and to separate meteor groups from different meteor showers with different radiants and velocities. The method makes it possible to increase the angular resolution from 10° × 10° achieved with a quasi-tomographic technique to 2° × 2°, with a prospect of a further increase in the accuracy through the individual reduction of separated meteor groups. We use the reduction of one-day-long observations during maximum activity of the Geminids meteor shower in 1993 to illustrate the potentialities of the method. We show an example of detecting a weak meteor shower that was active during December 1993. 相似文献
14.
D. I. Steel 《Earth, Moon, and Planets》1995,68(1-3):13-30
Various points are discussed concerning the association of Earth-crossing asteroids (ECAs) with meteoroid streams, including the drawbacks of the techniques used in some previous work. In comparing the theoretical radiants of any ECA (or, indeed, comet) with observed meteor radiants it is necessary that the orbit used be that appropriate for epochs when the ECA has a node at 1 AU; in each precession cycle of the argument of perihelion () there will be four values rendering a node at the Earth's orbit, so that four showers are expected. Precession of the node will result in sets of showers at different times of year from different-precession cycles, whilst for some objects the orbital evolution is more convoluted. For diffuse, low-flux showers a problem is differentiating the meteors associated with any ECA from the sporadic background; a new graphical technique is introduced for illuminating whether such associations exist. A re-evaluation is required of whether ECAs should be thought of as being parent bodies of specific showers. Although this might be the case for some very large ECAs (such as (3200) Phaethon, associated with the Geminid stream), the bodies observed now being extinct or dormant cometary cores, it is suggested that in general the ECAs are better thought of as being large fragments produced in hierarchical cometary disintegrations. That is, some ECAs are just the largest meteoroids in meteoroid streams. 相似文献
15.
Štefan Gajdoš 《Earth, Moon, and Planets》2008,102(1-4):117-123
A new meteroid stream—October Ursa Majorids—was announced by Japanese observers on Oct. 14–16, 2006 (Uehara et al. 2006).
Its weak manifestation was detected among coincidental major meteor showers (N/S Taurids, Orionids), as its meteors radiated
from a higher placed radiant on the northern sky. We have tried to find out previous displays of the stream throughout available
meteor orbits databases, and among ancient celestial phenomena records. Although we got no obvious identification, there are
some indications that it could be a meteor shower of cometary origin with weak/irregular activity, mostly overlayed by regular
coincidental meteor showers. With a procedure based on D-criterion (Southworth and Hawkins 1963) we found a few records in IAU MDC database of meteor photographic orbits which fulfill
common similarity limits, for October Ursae Majorids. However, their real association cannot be established, yet. With respect
to the mean orbit of this stream, we suggest for its parent body a long-period comet. 相似文献
16.
P.B. Babadzhanov 《Celestial Mechanics and Dynamical Astronomy》1997,69(1-2):221-234
Recent theoretical and observational work has shown that the asteroids belonging to the Taurid meteoroid complex have a cometary
nature. If so, then they might possess related meteoroid streams producing meteor showers in the Earth atmosphere. We studied
the orbital evolution of ten numbered Taurid complex asteroids by the Halphen-Goryachev method. It turned out that all of
these asteroids are quadruple crossers relative to the Earth's orbit. Therefore their proposed meteoroid streams may in theory
each produce four meteor showers. The theoretical orbital elements and geocentric radiants of these showers are determined
and compared with the available observational data. The existence of the predicted forty meteor showers of the ten Taurid
complex asteroids is confirmed by a search of the published catalogues of observed meteor shower radiants and orbits, and
of the archives of the IAU Meteor Data Center (Lund). The existence of meteor showers associated with the Taurid Complex Asteroids
confirms that, most likely, these asteroids are extinct comets.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
17.
David D. Meisel Johan Kero Csilla Szasz Vladimir Sidorov Stan Briczinski 《Earth, Moon, and Planets》2008,102(1-4):315-322
In the northern hemisphere, the month of February is characterized by a lack of major meteor shower activity yet a number
of weak minor showers are present as seen by the Kazan radar. Using the Feller transformation to obtain the distribution of
true meteor velocities from the distribution of radial velocities enables the angle of incidence to be obtained for the single
beam AO (Arecibo Observatory) data. Thus the loci of AO radiants become beam-centered circles on the sky and one can, with
simple search routines, find where these circles intersect on radiants determined by other means. Including geocentric velocity
as an additional search criterion, we have examined a set of February radiants obtained at Kazan for coincidence in position
and velocity. Although some may be chance associations, only those events with probabilities of association > 0.5 have been
kept. Roughly 90 of the Kazan showers have been verified in this way with mass, radius and density histograms derived from
the AO results. By comparing these histograms with those of the “background” in which the minor showers are found, a qualitative
scale of dynamical minor shower age can be formulated. Most of the showers are found outside the usual “apex” sporadic source
areas where it is easiest to detect discrete showers with less confusion from the background. 相似文献
18.
V. Sidorov S. Kalabanov S. Sidorova I. Filin T. Filimonova 《Earth, Moon, and Planets》2004,95(1-4):165-179
The discrete quasitomographic method of the analysis of the interferometric data of meteor radar gives us the possibility
of measuring coordinates and velocities of very weak meteor showers with a 2 × 2 square degree resolution on the celestial
sphere. The minimal rate of the meteors in each microstream is five meteors per day. At such sensitivity, basic distinctions
between irregularities of the sporadic background and meteor streams vanish. More than 1000 of the detected microshowers per
month are associated with a combination of (a) the large known meteor showers, (b) the weaker known meteor showers and (c)
till now unknown associations of microshowers. All microshowers regardless of association have the identical velocities, limited
areas of radiation and near simultaneity of their acting dates. The results are compiled as maps of radiant distribution and
average velocities of microstreams for different months. From these it is possible to see how the microshower activity for
various discrete sites on the celestial sphere correlate with the behavior of the well-known meteor streams and thus to infer
the orbital properties of the different microstream configurations. 相似文献
19.
We present the first clear observations of meteor shower activity from meteor-head echoes detected by a high-power large-aperture radar (HPLAR). Such observations have been performed at the Jicamarca VHF radar using its interferometric capabilities allowing the discrimination of meteor shower echoes from the much more frequent sporadic meteors. Until now, HPLARs were unable to distinguish meteor shower from the much more common sporadic meteor ones. In this work we have been able to detect and characterize the η-Aquariids (ETA) as well as the Perseids (PER) showers. The shower activity is more conspicuous for the ETA than for the PER shower due to the more favorable geometry. Namely, PER meteors come from low elevation angles, experiencing more filtering due to the combined Earth-atmosphere-radar instrument. In both cases, there is an excellent agreement between the measured mean velocity of the shower echoes and their expected velocity, within a fraction of 1 km s−1. Besides the good agreement with expected visual results, HPLARs observe meteors with a variety of particles sizes and masses, not observed by any other technique. Taking into account the different viewing volumes, compare to optical observations Jicamarca observes more than 1000 times more ETA meteors. Our results indicate that Jicamarca and other HPLARs are able to detect the echoes from meteor showers, but without interferometric capabilities such populations are difficult to identify just from their velocity distributions, particularly if their velocity distributions are expected to be similar to the more dominant distributions of sporadic meteors. 相似文献
20.
Since 2006, systematic double-station photographic observations of fireballs using all-sky cameras equipped with Zeiss Distagon “fisheye” objectives (f/3.5, f = 30 mm) with a 180° field of view have been carried out at two observatories, Gissar (GisAO) and Sanglokh (IAOS), of the Institute of Astrophysics of the Tajik Academy of Sciences. In the method of astrometric reduction of fireball photographs, the empirical formulae for converting the measured coordinates to horizontal celestial coordinates are used. These formulae contain 12 unknown constants to be determined by the least-squares method and the iteration method. Such an approach enables the determination of the coordinates of an object at any point of the celestial hemisphere with a precision close to the theoretical limit whose value is quite comparable with the measurement errors. In the photometric reduction, the dependence of the measured width of the diurnal star trails on their magnitudes was used. As a result of astrometric and photometric reduction of the double-station photographs of five fireballs, the data on atmospheric trajectories, the coordinates of radiants, orbits in interplanetary space, light curves, and photometric masses of meteoroids which produced fireballs were obtained, and the belonging of fireballs to the known meteor showers was determined as well. 相似文献