Photographic Orbits Research Articles

Leonids in the IAU MDC database

The structure of the Leonid meteor stream was studied using the IAU MDC Photographic Orbits Database. Two notable peaks of activity of photographic Leonids were identified at λ⊙ = 234.5° and λ⊙ = 235.5°. Two smaller peaks were tentatively found at λ⊙ = 236.6° and λ⊙ = 235.9°. The first identified peak of the shower activity is formed merely by the meteors observed in the year 1998; the second one is composed mainly of Leonids observed in the years 1998 and 1999. The smaller peaks of activity are formed by the meteors observed in the years 2001 and 2002. The peaks of activity of three different types of meteors - photographic, visual, and radar as well, were in the year 1999 observed almost at the same solar longitude. This feature of the Leonid trail which caused the 1999 shower is in contrast to many other meteor streams (e.g. Orionids) that are characterized by a shift in the peak of activity depending on the mass of recorded meteoroids. In a comparison with other showers with comparable numbers of meteors listed in the IAU MDC database, the Leonids seems to have an incomparable inner structure. Each of six identified associations of orbits is composed of meteors observed mainly in one individual year. Declination of two associations composed of meteors observed mainly from 1999 does not fit the theoretical trend of the daily motion of the radiant. The results confirm the observation of a spatially separated dust trail of Leonids in 1999.

Park Forest (L5) and the asteroidal source of shocked L chondrites

AbstractThe Park Forest (L5) meteorite fell in a suburb of Chicago, Illinois (USA) on March 26, 2003. It is one of the currently 25 meteorites for which photographic documentation of the fireball enabled the reconstruction of the meteoroid orbit. The combination of orbits with pre‐atmospheric sizes, cosmic‐ray exposure (CRE), and radiogenic gas retention ages (“cosmic histories”) is significant because they can be used to constrain the meteoroid's “birth region,” and test models of meteoroid delivery. Using He, Ne, Ar, 10Be, and 26Al, as well as a dynamical model, we show that the Park Forest meteoroid had a pre‐atmospheric size close to 180 g cm−2, 0–40% porosity, and a pre‐atmospheric mass range of ~2–6 tons. It has a CRE age of 14 ± 2 Ma, and (U, Th)‐He and K‐Ar ages of 430 ± 90 and 490 ± 70 Ma, respectively. Of the meteorites with photographic orbits, Park Forest is the second (after Novato) that was shocked during the L chondrite parent body (LCPB) break‐up event approximately 470 Ma ago. The suggested association of this event with the formation of the Gefion family of asteroids has recently been challenged and we suggest the Ino family as a potential alternative source for the shocked L chondrites. The location of the LCPB break‐up event close to the 5:2 resonance also allows us to put some constraints on the possible orbital migration paths of the Park Forest meteoroid.

Orionids and Eta Aquariids in the IAU MDC database

The structure of the Orionids and the Eta Aquariids meteor streams was studied using the IAU MDC Photographic Orbits Database. Both the streams are associated with one of the most active comet known in the cometary population – 1P/Halley. The stream is therefore constantly supplemented by new particles, what creates conditions for a formation of a complex internal structure. We found that two frequency maxima of the photographic Orionids identified at the solar longitudes λ⊙=208.5° and λ⊙=210.5° coincide with the positions of the maximum activity of the visual meteors and bolides. One of five identified associations (O1) probably does not belong to the Orionids, i.e. meteor stream 008 ORI, but regards the September omicron Orionids - 479 SOO. The orbital parameters of the filament O4 correspond to the mean orbit of the Orionids resulting from the meteor radar observations in the period 2002–2012. There is no spatial relation between meteors observed in May (031 ETA) and October (008 ORI). While Eta Aquariids are in fact the core of the stream, the orbits of Orionids are much further from the cometary orbit.

Variation of sporadic meteor background and solar activity

Observations of the sporadic background meteors in 1996-2007 by the Bologna-Lecce-Modra forward-scatter radio system operating along two baselines are analyzed and discussed. The activity curves of sporadic meteor echoes and their variations indicate a direct correlation with the solar activity represented by the sunspot relative number R , as well as with the solar coronal index CI . The mass distribution exponents and its variations in the period of the 23rd solar cycle indicate a relatively stable population of the sporadic background meteoroid population in the surroundings of the Earth’s orbit. Investigation of meteor heights compiled from the IAU MDC catalogue of precise photographic orbits for a period of five solar cycles do not exhibit any pronounced variation consistent with the solar cycle activity.

The occurence of interstellar meteoroids in the vicinity of the Earth

AbstractIf interstellar meteors are present among the registered meteor orbits, the distribution of the excesses of their heliocentric velocities should correspond to the distribution of radial velocities of close stars. Hence, for the velocity vi = 20 kms−1 of an interstellar meteor (with respect to the Sun) we obtain a heliocentric velocity vH = 46.6 kms−1 of an interstellar meteor arriving at the Earth. Moreover, a concentration of radiants to the Sun's apex should be observed. An analysis of the hyperbolic meteors among the 4581 photographic orbits of the IAU Meteor Data Center showed that the identification of the vast majority of the hyperbolic orbits in these catalogues has been caused by an erroneous determination of their heliocentric velocity and/or other parameters. Any error in the determination of vH, especially near the parabolic limit, can create an artificial hyperbolic orbit that does not really exist. On the basis of photographic meteors from the IAU MDC, the proportion of possible interstellar meteors decreased significantly (greater than 1 order of magnitude) after error analysis and does not exceed the value 2.5 × 10−4. Neither any concentration of radiants to the Sun's apex, nor any distribution following the motion of interstellar material has been found.

Search for Past Signs of October Ursae Majorids

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.

The Lyrid Meteor Stream: Orbit and Structure

A filamentary structure in the Lyrid meteor stream based on photographic orbits available in the IAU Meteor database is identified and studied. About 17 Lyrids are found in the database and the stream mean orbit is derived. The shower radiant is compact, of a size 2° × 1.5°. Applying a stricter limiting value for the Southworth-Hawkins D-criterion, two distinct filaments in the stream, on a short and a long period orbit, are separated. To confirm their consistency as filaments, their orbital evolution over 5,000 years is investigated.

Semimajor axes of the orbits and ejection velocities of Perseid meteoroids

Photographic orbits of meteors are combined with modeling of the ejection of Perseids during the perihelion passage of comet Swift-Tuttle in 1862 to analyze the most likely ejection velocities of particles from the comet nucleus. Given the scatter of the semimajor axes of observed Perseids with masses greater than 10−4 g, the most likely interval of ejection velocities spans 0 to 300 m/s for particles ejected in the plane of the comet orbit in the retrograde direction and in the direction of the comet’s anomalous tail.

A Fine Structure of the Perseid Meteoroid Stream

A fine structure of the Perseid stream in the range of photographic magnitudes is studied using the method of indices. A new completed 2003 version of the IAU Meteor Data Center Catalogue of 4581 photographic orbits is used. The method of indices is used to acquire a basic data set for the Perseids. Subsequently, the method is applied on the chosen Perseids to study their structure. Sixty four percent of chosen Perseids taken into account are attached to one of the 17 determined filaments of orbits. The filaments are not distributed in the space accidentally, but they form a higher structure consisting of at least four well-defined and distinguished “branches”.

Bolide meteor streams

The current version of the IAU Meteor Data Centre catalogue of photographic orbits comprising the orbital and geophysical data of 4581 meteors is applied for a more representative search of the mean orbits of bolide meteor streams among photographic meteors. We have made the search based on a computerized stream search procedure utilizing the Southworth-Hawkins D-criterion. The results are compared with the previous similar analysis made by Porubčan & Gavajdová (1994).To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

A search for streams and associations in meteor databases. Method of Indices

A new method of searching for minor meteor streams and associations is presented and discussed. The procedure, based only on mathematical statistics, enables a parallel separation of major and minor streams or associations. The approach utilizes a division of the ranges of examined parameters into equidistant intervals. The method is tested on the IAU Meteor Data Center Lund catalogue of precise photographic orbits representing the most extensive set of photographic meteor orbits. Besides the five orbital elements incorporated in the Southworth–Hawkins D-criterion, we have also included in the procedure the coordinates of the radiant which belong to the most accurately known parameters and the geocentric velocity as a significant parameter characteristic for physically related orbits. The basic idea of the procedure is a division of the observed ranges of parameters into a number of equidistant intervals and assignment of indices to a meteor according to the intervals pertinent to its parameters. The meteors with equal indices are regarded as mutually related. Since various parameters listed in the catalogue contain various relative errors, it is necessary to use several intervals in the division of each parameter to obtain a good fit with the real orbital distribution. The relative ratios, approximated by small integers, corresponding to the reciprocal values of the relative errors, were applied as the basic numbers for the division of the parameters. To test the quality of this method, the first step presented in this paper is aimed at wider intervals providing a less detailed classification (a smaller branching). In this step all the major streams (except of the northern branch of δ-Aquarids) were identified, confirming the efficiency of the procedure. After combining the related groups, 16 streams were identified. The search program also identifies widely spread Taurids. There are separated orbits pertinent to some minor streams such as the o-Draconids, κ-Cygnids, October Draconids, Pegasids and December Monocerotids. Rather surprisingly, even at this strict level, a pair of meteors in orbits similar to the Lyrids with the maximum on April 8 (Arter and Williams, 1995. Earth, Moon, Planets 68, 141–153) are identified. In the next steps the search will be concentrated on the separation of minor streams and eventually some so far unknown associations.

Determination of the period of activity of meteoroid streams

A method for determination of the period of activity of meteoroid streams from photographic orbits is presented and discussed. It is also aimed at identifying stream members from marginal regions of activity. The search utilizes the Southworth-Hawkins D criterion. The primary separation of meteoroid stream members is based on the cumulative distribution of D. Variations of the orbital elements q, e, w and i with the solar longitude were derived from a set of selected orbits and applied to a search for the stream members from marginal regions of activity. Since the radiant is one of the most reliable parameters derived from observation, deviations of individual radiants from the stream radiant were taken as an additional criterion for a final stream membership classification. An application of the procedure to nine major streams led in the case of four streams to a probable assignment of meteors to the stream before or after the so far known “classical” period of activity: δ Aquarids (1), Perseids (8), Leonids (3) and Geminids (1). The significant number of Perseids found prior to July 23 (the onset of the stream activity) and the relatively small dispersion of their angular elements suggest that their assignment to the stream is rather reliable.

The orbit of the Kappa Cygnid and related meteor streams

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 α = 277°.6,δ = 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.

On the activity and orbit of the Geminids meteorid stream

The activity of the Geminids meteor shower is studied on the basis of radio observations carried out by the Budrio meteor radar in 1986. The 1986 Geminids have displayed as a distinct meteor shower with an asymmetric curve of activity, the duration between the points of one-quarter strength being 6 days and the maximum at the solar longitude of about 260°.75 (1950.0). The mean orbit and radiant ephemeris of the Geminids are derived on the basis of 191 precise photographic orbits available from the IAU Meteor Data Centre in Lund. Over a time span of 50 years, the semi-major axis, eccentricity and perihelion distance of the stream exhibit variations following the trend of the stream evolution suggested by Williams and Wu.

A search for fireball streams among photographic meteors

Terentjeva ( Asteroids, Comets, Meteors III, pp. 579–584. Uppsala Univ. Press, Uppsala, 1990) in her analysis of 554 fireball orbits reported that she found 78 fireball streams. The present paper summarizes a similar analysis of a set of over 1000 photographic orbits of meteors brighter than magnitude — 3. Fireball streams are searched for using a computerized stream-search procedure based on the Southworth-Hawkins D discriminant, considering their radiants, daily motion and the sizes of the radiant areas. Except for the fireball belonging to the known meteoroid streams a substantially lower number of possible fireball streams was found. The mean orbits, radiants and periods of activity of the streams are presented.

The activity and orbit of the Perseid meteor stream

The activity profile and orbit of the Perseid meteor stream is investigated based on 605 photographic orbits obtained at various meteor stations in the period 1937–1985. The study shows that the derived activity profile of the stream depends strongly on the resolution in solar longitude used by the investigator. If the activity profile is investigated at a high resolution in solar longitude two distinct Perseid maxima appear, one at solar longitude 138.97° and a second at 139.61°. A more detailed investigation shows that the Perseid maximum has gradually changed with time, being located at approximately 139.5–139.6° in the period 1940–1969 and at 138.9–139.0° in the period 1970–1989. We interpret this shift as indicating a gradual increase in the ratio of new to old cometary material as comet 1992t (Swift-Tuttle) approached perihelion. An investigation of the scatter in the orbital parameters of the two maxima shows that the scatter in all orbital elements is larger in the “old” peak. The mean orbit of the stream based on all 605 orbits agrees well with that of comet P/Swift-Tuttle (1992t). The main discrepancy is in the ascending node and in the argument of perihelion, where the comet differs by about 0.40° and 2.4°, respectively, from that of the meteor stream. However, if separate mean orbits are computed for the two Perseid maxima, an orbit determination based only on the “new” maximum reduces these differences to 0.21° and 1.33°, respectively. The present study concentrates on bright meteors obtained in photographic two-station studies. It is likely that a similar two-peak structure can be detected in visual and radar data as well.

Two computerized stream searches among meteor orbits: 1. Among 865 precise photographic orbits [and] 2. among 2401 photographic orbits

Two computerized stream searches among meteor orbits: 1. Among 865 precise photographic orbits [and] 2. among 2401 photographic orbits

40. Investigation of minor meteor streams

The paper consists of three sections: (1)In continuation of a previous paper by the author, on 154 minor meteor streams, elements of orbits and other data are presented for an additional 95 minor streams (most of them less active). These streams have been found both by the studies of the photographic orbits of meteor bodies known before, and from the visual radiants of faint showers.(2)The problems of a possible family of six minor meteor streams associated with the Lexell comet 1770-I, and the connection between nine other minor streams and long-period comets, are examined. The assumption is made that nearly-parabolic comets may be accompanied by meteor streams of considerable width.(3)Radiants and elements of the orbits for 30 meteor bodies of the Cyclids are described, as were established by photographic data. Perturbed motion of one such meteor body is investigated by numerical integration of differential equations of motion on the electronic computer BESM-2, using Cowell's method of quadratures and taking account of perturbations from six planets (Venus–Uranus) and of high-order terms through to the 4th order. Over the time interval studied of 45 years the orbit of the Cyclids has been stable. Perturbing action of the Earth does not lead to any substantial changes in the elements of the orbits. Even at close approaches of the order of 0–003 AU the changes in the angular elements are not greater than about 1°.

Photographic α-Capricornid meteors.

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Photographic α-Capricornid meteors. Wright, Frances W. ; Jacchia, Luigi G. ; Whipple, Fred L. Abstract An analysis of the radiants and orbits from twelve double-station and forty-nine single- station meteors leads to two possible working hypotheses for the nature of the a-Capricornid stream: (i) A continuous stream of a single origin, observable from July i6 to August 22 and comprising several small visual showers observed in the past. (2) Two, or possibly more, independent streams: the first from July i6 to August 1 and a second from August 1 to August 22. On the first hypothesis the daily equatorial motion is then 52' + ~~~ eastward and 2' + 2 6 southward per day for the mean corrected radiant; from a = 294?5, ~ =- 9?3 (1950) on July 16-17 to a = 325?I, ~ = - Io?2 (1950) on August 21-22. The inclination of the mean radiant path to the ecliptic is about 190, and maximum activity occurs around August 1. The twelve double-station meteors provide the first accurate orbits for the a-Capricornids; values for mean elements for the two hypotheses mentioned above appear in the following table: MEAN ORBITAL ELEMENTS Second bypotbesis First July August Comet bypothesis stream stream 1p45n Vel. (km/sec) 25.53 25.14 25.96 24 P (years) 4.28 3.61 5.02 4.996 i 4?o 7?o o?6 13?I5 Pen (a.u.) 0.566 0.570 0.563 o.~~8 Aph. (a.u.) 4.682 4.14 5.29 5.286 7r 43?3 34?4 53?2 56?8 It is evident that the aphelia are well within Jupiter's orbit for the July stream, and about it for the August stream, without much continuity between the two streams. The a-Capriconids appear not to be related to either of the two parent comets previously suggested by other investigators, Comets i88i V or 1457 II. Also, the a-Capricornid orbits, together with a few photographic orbits of the -Aquarid meteors prove that Comet i948n is definitely not associated with the t-Aquarids, as Rigollet deduced from less accurate orbits, but that Comet I948n is a better possible parent comet for the later a-Capriconids. The mean deviation of an extended meteor trial from the mean moving radiant of the a-Capricornids is 127', the largest scatter yet obtained for photographic showers of the Harvard Meteor Program. The previously determined scatter-duration curve would predict only 38'. There is also a steady increase in the scatter, from 88' for the early part to 132' from August 6 to August 22, quite independent of mass (luminosity). The irregular frequency distribution of meteors with date during the shower, the unusually large scatter in radiants, the large increase in scatter with date, the high inclination of the radiant path to the ecliptic, and the increase of both aphelion distance and longitude of perihelion with date suggest strongly that the stream is impure, probably of a double or possibly of a multiple origin. Harvard College Observatory, Cambridge, Mass. Publication: The Astronomical Journal Pub Date: 1955 DOI: 10.1086/107124 Bibcode: 1955AJ.....60..183W full text sources ADS |

A study of the smoke cloud over Washington, D. C., on January 16, 1926

A method for determination of the period of activity of meteoroid streams from photographic orbits is presented and discussed. It is also aimed at identifying stream members from marginal regions of activity. The search utilizes the Southworth-Hawkins D criterion. The primary separation of meteoroid stream members is based on the cumulative distribution of D. Variations of the orbital elements q, e, w and i with the solar longitude were derived from a set of selected orbits and applied to a search for the stream members from marginal regions of activity. Since the radiant is one of the most reliable parameters derived from observation, deviations of individual radiants from the stream radiant were taken as an additional criterion for a final stream membership classification. An application of the procedure to nine major streams led in the case of four streams to a probable assignment of meteors to the stream before or after the so far known “classical” period of activity: δ Aquarids (1), Perseids (8), Leonids (3) and Geminids (1). The significant number of Perseids found prior to July 23 (the onset of the stream activity) and the relatively small dispersion of their angular elements suggest that their assignment to the stream is rather reliable.